WO2026002579A1

WO2026002579A1 - Method for operating a multiple particle beam system and multiple particle beam system having electrostatic trapping electrodes and/or a trapping trench system for protecting the micro-optical unit

Info

Publication number: WO2026002579A1
Application number: PCT/EP2025/065633
Authority: WO
Inventors: Alexander Borovik; Stefan Schubert; Gero STORECK; Hadi Sedaghat-Pisheh; Georg Kurij; Ralf Lenke
Original assignee: Carl Zeiss Multisem GmbH
Current assignee: Carl Zeiss Multisem GmbH
Priority date: 2024-06-28
Filing date: 2025-06-05
Publication date: 2026-01-02
Anticipated expiration: 2026-12-28
Also published as: DE102024118384A1

Abstract

What is disclosed is a multiple particle beam system and a method for operating same in a decontamination mode, wherein charged disturbance particles situated in a sensitive region of a multi-aperture arrangement (350) are trapped and removed from the sensitive region. Electrostatic trapping electrodes (361, 362) may be arranged and controlled in a specific way and/or a trapping trench system (381-383) may be used for trapping the charged disturbance particles. The charged disturbance particles are stored during the normal operating mode of the multiple particle beam system in such a way that the charged disturbance particles do not disturb normal operation.

Description

Method for operating a multiple particle beam system and multiple particle beam system having electrostatic trapping electrodes and/or a trapping trench system for protecting the micro-optical unit

Field of the invention

The invention relates in general to multiple particle beam systems that operate with a multiplicity of individual charged particle beams, such as multi-beam particle microscopes or lithography systems. The invention specifically relates to a method for operating a multiple particle beam system and to a multiple particle beam system having electrostatic trapping electrodes and/or a trapping trench system for protecting the micro-optical unit or multiaperture arrangement.

Prior art

With the ongoing development of ever smaller and ever more complex microstructures such as semiconductor components, there is a need to further develop and optimize planar production techniques and inspection systems for producing and inspecting small dimensions of the microstructures. For instance, the development and production of the semiconductor components require monitoring of the design of test wafers, and the planar production techniques require process optimization for reliable production with high throughput. Moreover, there have been recent demands for an analysis of semiconductor wafers for reverse engineering and for a customized, individual configuration of semiconductor components. Therefore, there is a need for inspection means which can be used with high throughput to examine the microstructures on wafers with high accuracy.

Typical silicon wafers used in the production of semiconductor components have diameters of up to 300 mm. Each wafer is divided into 30 to 60 repeating regions ("dies") with a size of up to 800 mm². A semiconductor apparatus comprises multiple semiconductor structures, which are produced in layers on a surface of the wafer by planar integration techniques. Semiconductor wafers typically have a plane surface on account of the production processes. The feature size of the integrated semiconductor structures in this case extends from a few pm to the critical dimensions (CD) of a few nanometres, and the feature sizes will become even smaller in the near future; the expectation is that in future the feature sizes or critical dimensions (CD) will correspond to the 3 nm, 2 nm or even smaller technology nodes of the International Technology Roadmap for Semiconductors (ITRS). In the case of the aforementioned small feature sizes, defects of the order of the critical dimensions must be identified quickly over a very large area. For multiple applications, the specification requirement regarding the accuracy of a measurement provided by an inspection device is even higher, for example by a factor of two or one order of magnitude. For instance, a width of a semiconductor feature must be measured with an accuracy of better than 1 nm, for example 0.3 nm or even less, and a relative position of semiconductor structures must be determined with an overlay accuracy of better than 1 nm, for example 0.3 nm or even less.

The mSEM, a multi-beam scanning electron microscope, is a relatively new development in the field of charged particle systems (charged particle microscopes, CPMs). For instance, a multi-beam scanning electron microscope is disclosed in US 7 244 949 B2 and in US 2019/0355544 A1. In the case of a multi-beam electron microscope or mSEM, a sample is irradiated simultaneously by a multiplicity of individual electron beams arranged in a field or grid. For instance, 4 to 10 000 individual electron beams can be provided as primary radiation, with each individual electron beam being separated from an adjacent individual electron beam by a pitch of 1 to 200 micrometres. For example, an mSEM has approximately 100 separate individual electron beams ("beamlets"), which are arranged for example in a hexagonal grid, with the individual electron beams being separated by a pitch of approximately 10 pm. The multiplicity of charged individual particle beams (primary beams) are focused on a surface of a sample to be examined by way of a common objective lens. For example, the sample can be a semiconductor wafer that is secured to a wafer holder mounted on a movable stage. When the wafer surface is illuminated by the charged primary individual particle beams, interaction products, for example secondary electrons or backscattered electrons, emanate from the surface of the wafer. Their start points correspond to those locations on the sample on which the multiplicity of primary individual particle beams are focused in each case. The amount and the energy of the interaction products depend on the material composition and the topography of the wafer surface. The interaction products form a plurality of secondary individual particle beams (secondary beams), which are collected by the common objective lens and, by virtue of a projection imaging system of the multi-beam inspection system, are incident on a detector arranged in a detection plane. The detector comprises a plurality of detection regions, each of which comprises a plurality of detection pixels, and the detector captures an intensity distribution for each of the secondary individual particle beams. An image field of 100 pm x 100 pm, for example, is obtained in the process.

The multi-beam electron microscope of the prior art comprises a sequence of electrostatic and magnetic elements. At least some of the electrostatic and magnetic elements are adjustable in order to adapt the focus position and the stigmation of the multiplicity of charged individual particle beams. The multi-beam system with charged particles of the prior art moreover comprises at least one crossover plane of the primary or the secondary charged individual particle beams. Moreover, the prior art system comprises detection systems in order to facilitate the adjustment. The multi-beam particle microscope of the prior art comprises at least one beam deflector (deflection scanner) for collective scanning of a region of the sample surface by means of the multiplicity of primary individual particle beams in order to obtain an image field of the sample surface.

What is known as a beam splitter (or alternatively beam separator or beam divider) is used to separate the particle-optical beam path of the primary beams from the particle-optical beam path of the secondary beams. Separation is effected by means of specific arrangements of magnetic fields and/or electrostatic fields, for example by means of a Wien filter.

In the case of multiple particle beam systems, a distinction is made in principle between systems that work with a single column and systems that work with a plurality of columns. In systems with a single column, the individual particle beams at least in part pass through the same particle-optical unit or through one or more global particle lenses. In addition, in a single column, the individual particle beams are relatively close to one another. Despite the partially global particle-optical elements, there is the need for individual influenceability and/or shapeability of the individual particle beams even in the case of single columns, in order to correct imaging aberrations such as image field curvature, field astigmatism and other aberrations. A so-called micro-optical unit can be used for this individual influencing and/or shaping of the individual particle beams. The micro-optical unit often also serves as a multibeam generator for generating and shaping a multiplicity of individual particle beams. In this case, the multi-beam generator or the micro-optical unit comprises a sequence of a plurality of multi-aperture plates in order firstly to generate a multiplicity of individual particle beams and in order secondly to shape them as well, such that they have the properties required for the subsequent particle-optical imaging. During the generation of the multiplicity of individual particle beams, normally an expanded individual particle beam is incident on a first multiaperture plate or filter plate and passes through the openings thereof, such that after said beam has passed through the openings, a multiplicity of individual particle beams are present instead of the individual particle beam. During subsequent beam shaping by means of a or further multi-aperture plate(s), use is made of electrodes which for example are provided in the region of the apertures of a multi-aperture plate and which are collectively or individually controllable. The electrodes can be for example ring electrodes or multi-pole electrodes. According to another example, a multi-aperture plate can have a monolithic form, with a voltage applied to the multi-aperture plate overall, i.e. the monolithic multi-aperture plate is then at a certain potential, and so its openings can create a lens effect in interaction with other particle-optical elements. Other configurations of a multi-aperture plate for active beam shaping are also possible.

In addition to the described arrangement of multi-aperture plates, the multi-beam generator can also comprise one or more single aperture plates having an individual central opening, which are used for example as a pre-aperture or as a global electrode for the beam shaping.

In order to produce micro-optical units, use is made for example of MEMS techniques or planar integration techniques, i.e. the same methods also used for semiconductor production.

A multi-beam generator that operates reliably and precisely is very important for a multiple particle beam system. Errors and inaccuracies in the generation and shaping of the individual particle beams adversely affect the subsequent particle-optical imaging. Moreover, it is very important for actually all of the multiplicity of individual particle beams to be exactly formed and shaped.

One problem in connection with multi-beam generators is contaminations that occur even when a multiple particle beam system is operated in a high vacuum. Specifically, tiny contaminants in the form of small solid particles or dust may occur. If these particles settle on the multi-beam generator or on the multi-aperture arrangement thereof or in the vicinity of said generator/arrangement, then there is the risk of the particles being charged during operation of the multiple particle beam system or even being burnt into a multi-aperture plate. Instances of charging or electrostatic fields in turn adversely influence the shape and/or position of the individual particle beams. The imaging properties of the multiple particle beam system deteriorate. It is therefore desirable to avoid even extremely small contaminations of the multiple particle beam generator.

US 10,861 ,666 B1 describes avoiding contaminations by dust particles in charged single-beam systems and in multiple particle beam systems, specifically in the region of the (individual) particle source or in the region of the emitter/cathode tip (also called “gun”). Unwanted discharges in the region of the cathode tip or arc discharges (“arcing”) are intended to be avoided. US 10,861 ,666 B1 therefore discloses, near the cathode tip, the arrangement of a trapping electrode, in particular a ring-shaped trapping electrode, which is activated before the actual operation of the emitter, such that charged particles present in the emitter region migrate to the trapping electrode and settle there. The trapping electrode remains activated during the actual operation of the particle beam system as well. Moreover, a shielding element is disclosed, for shielding the electrostatic field of the trapping electrode during the normal operation of the particle beam system. In addition, according to US 10,861 ,666 B1 , it is also possible to employ two ring-shaped trapping electrodes, which are arranged at different positions and with different diameters around the particle-optical axis, but otherwise are used or switched in the same way.

Although US 10,861 ,666 B1 also mentions multi-beam particle beam systems, the patent does not indicate the particular requirements of multi-beam particle beam systems; the specific problem with a multi-beam generator is not mentioned.

WO 2023/ 143 858 A1 and its family member US 2024/ 371 596 A1 relate to a multi-beam charged particle microscope system with a mirror mode of operation, a method for operating a multi-beam charged particle microscope system with a mirror mode of operation and an associated computer program product. The multi-beam charged particle microscope system can be operated to record a stack of images in a mirror imaging mode. The stack of images comprises at least two images of two different settings of at least on multi-aperture element, for example a focus stack, which allows the multi-beam charged particle microscope system to be inspected and recalibrated thoroughly. Furthermore, decharging and cleaning of multiaperture plates is briefly mentioned without further details.

Description of the invention

The object of the present invention is to provide an improved multiple particle beam system whose performance depends to a lesser extent on contaminations present in the form of small solid particles. In particular, it is an object of the invention to better protect a multi-beam generator or a multi-aperture arrangement of a multiple particle beam system against contaminations in the form of solid particles.

The object of the invention is achieved by the subject matter of the independent patent claims. Advantageous embodiments of the invention are evident from the dependent patent claims.

The present patent application claims the priority of German patent application No. 10 2024 118384.5 filed on 28 June 2024, the disclosure of which in the full scope thereof is incorporated in the present patent application by reference. In accordance with a first aspect of the invention, the latter relates to a method for operating a multiple particle beam system, thereby making it possible to reduce contaminations by disturbance particles. In principle, for this purpose, the method according to the invention involves firstly providing a multiple particle beam system having a specific combination of features, then operating the multiple particle beam system in a decontamination mode, before the multiple particle beam system is operated thereafter in a normal operating mode. These fundamental method steps will be described in greater detail below.

An initial method step involves providing a multiple particle beam system having a multiaperture arrangement and having at least two trapping electrodes. The multi-aperture arrangement can be part of a multi-beam generator, but in principle it can also be provided elsewhere or as a different component part in the multiple particle beam system. The multiaperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multiaperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region. In a normal operating mode of the multiple particle beam system, a multiplicity of charged individual particle beams pass through the multiplicity of apertures in the multi-aperture region. In particular, the individual particle beams can be formed as a result. The multi-aperture region of the multi-aperture arrangement is part of the sensitive region of the multi-aperture arrangement. In the sensitive region, contaminations by disturbance particles and in particular by charged disturbance particles are particularly disturbing since they have an influence on the individual particle beams formed. The outer region arranged around the multi-aperture region is less sensitive here. The outer region normally does not comprise any apertures either, at any rate not for the standard operation of a multiple particle beam system in the normal operating mode. Nevertheless, (other) apertures can be provided in the outer region, for example for adjustment purposes or current measuring purposes. The outer region directly adjoining the multi-aperture region is normally also part of the sensitive region of the multi-aperture arrangement. In this inner edge region of the outer region, charged disturbance particles can generate disturbance fields and charged disturbance particles can also migrate from this edge region of the outer region to the multi-aperture region and generate disturbance fields there.

The first trapping electrode is formed in a manner substantially extending circumferentially around the particle-optical axis Z of the multiple particle beam system. Furthermore, it is arranged in a manner projected along the direction of the particle-optical axis onto the multiaperture arrangement in the outer region thereof. In other words, the first trapping electrode is arranged above or below the outer region, rather than somewhat above or below the multiaperture region. The same applies, mutatis mutandis, to the second trapping electrode: The latter is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis Z onto the multi-aperture arrangement in the outer region thereof. In this case, the second trapping electrode is arranged further away from the particle-optical axis than the first trapping electrode.

The initial method step of providing the multiple particle beam system is followed by operating the multiple particle beam system in a decontamination mode, which involves trapping charged disturbance particles in the sensitive region of the multi-aperture arrangement. In this case, the decontamination mode comprises the following steps (a) to (c) in the specified order:

Step (a) involves providing the same potential at the multi-aperture arrangement, at the first trapping electrode and at the second trapping electrode. This identical potential can be earth potential, for example, but this is not necessarily the case.

Step (b) involves changing the potential at the first trapping electrode and generating a first electrostatic trapping field between the first trapping electrode and the multi-aperture arrangement, such that charged disturbance particles can migrate from the multi-aperture arrangement to the first trapping electrode. The choice of the sign of the potential at the first trapping electrode or the direction of the first electrostatic trapping field is expediently chosen here such that charged disturbance particles that are charged with a charge having a specific sign can be trapped in the first electrostatic trapping field by the first trapping electrode and move away from the multi-aperture arrangement. The sign of the charge in turn results from the specific conditions of the multiple particle beam system. If a high-energy electron beam, for example, is employed in a normal operating mode of the multiple particle beam system, for example comprising electrons that have been accelerated to multiple keV, for example 20 keV, 25 keV, 30 keV or more, then negatively charged ions should be expected in the vicinity of the multi-aperture arrangement, and so a positive trapping potential at the first trapping electrode may be expedient. A large amount of backscattered secondary electrons in the region of the multi-aperture arrangement, for example within the multi-beam generator vacuum chamber, can also predominantly lead to the formation of negatively charged disturbance particles, and so a positive potential at the first trapping electrode may be expedient here as well. In principle, these considerations apply equally to all trapping electrodes. A step (c) involves changing the potential at the second trapping electrode and generating a second electrostatic trapping field between the second trapping electrode and the first trapping electrode. In this case, the second electrostatic trapping field is stronger than the first electrostatic trapping field, such that charged disturbance particles can migrate from the first trapping electrode to the second trapping electrode. It is preferably the case that, as a result, charged disturbance particles firstly trapped by means of the first trapping electrode are passed on to the second trapping electrode. Moreover, it is possible, of course, for charged disturbance particles that have not yet previously been trapped also to be trapped directly by the second trapping electrode.

After method steps (a), (b) and (c) of the decontamination mode have been carried out, the multiple particle beam system is then operated in a normal operating mode, in which the multiplicity of charged individual particle beams pass through the multi-aperture arrangement or wherein said beams are formed. In this case, in the normal operating mode, the same potential is provided at the multi-aperture arrangement and at the first trapping electrode. Furthermore, a potential different from that provided at the multi-aperture arrangement is provided at one of the other trapping electrodes, such that the charged disturbance particles remain at this trapping electrode, which constitutes a storage trapping electrode, in the normal operating mode. If exactly two trapping electrodes are provided in the region of the multiaperture arrangement, then the second trapping electrode is automatically the storage trapping electrode. Providing the same potential at the multi-aperture arrangement and at the first trapping electrode avoids a situation in which, during normal operation, an electrostatic field of the trapping electrode adversely influences the beam generation and beam shaping by means of the multi-aperture arrangement. Preferably, earth potential is present at the multi-aperture arrangement and at the first trapping electrode in the normal operating mode, but this need not be the case.

In accordance with one preferred embodiment of the invention, more than two trapping electrodes are provided in the region of the multi-aperture arrangement, wherein a potential different from that provided at the multi-aperture arrangement is provided at exactly one of the trapping electrodes in the normal operating mode. This reduces electrostatic disturbance fields that may result from trapping electrodes or from just one storage trapping electrode.

In accordance with one preferred embodiment of the invention, the exactly one trapping electrode or storage trapping electrode at which a different potential from that at the multiaperture arrangement is provided is that one of the trapping electrodes which is situated furthest towards the outside relative to the particle-optical axis Z of the multiple particle beam system. This storage trapping electrode is thus the furthest away from the sensitive region of the multi-aperture arrangement, which is why possible residual fields or disturbance fields there have the least influence on the charged individual particle beams.

In accordance with one preferred embodiment of the invention, in the decontamination mode after step (c) the following method step is furthermore carried out:

Step (d) involves changing the potential at the first trapping electrode, wherein the direction of the second electrostatic trapping field is not changed as a result. This measure facilitates as it were the passing on of charged disturbance particles from the first trapping electrode to the second trapping electrode. A number of possibilities exist for specifically changing the potential at the first trapping electrode: In accordance with one embodiment variant, the potential at the first trapping electrode is reduced in terms of its absolute magnitude while maintaining its sign. This reduction can be effected abruptly or continuously. It can also be effected in a plurality of steps of equal size. In accordance with one embodiment variant, the potential at the first trapping electrode is set to earth potential. It is also possible firstly to reduce the potential while maintaining its sign and finally to set it to earth potential. In accordance with a further embodiment variant, the polarity of the potential of the first trapping electrode is reversed. Instead of merely weakening the first electrostatic trapping field, in this way it is possible to actively repel charged disturbance particles at the first trapping electrode. This may be expedient for example if the first trapping electrode and the second trapping electrode are comparatively far away from one another. The polarity reversal can also be effected continuously or stepwise or in a single step.

In accordance with one preferred embodiment of the invention, a third trapping electrode is provided, which is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof. In this case, the third trapping electrode is arranged further away from the particle-optical axis Z than the second trapping electrode. In accordance with this embodiment of the invention, after step (c) and in particular after the optional step (d) in the decontamination mode the following step is furthermore carried out:

Step (e) involves changing the potential at the third trapping electrode and generating a third electrostatic trapping field between the third trapping electrode and the second trapping electrode. In this case, the third electrostatic trapping field is stronger than the second electrostatic trapping field, such that charged disturbance particles can migrate from the second trapping electrode to the third trapping electrode. What has already been stated in connection with the migration of charged disturbance particles from the first trapping electrode to the second trapping electrode analogously applies to this passing on of charged disturbance particles from the second trapping electrode to the third trapping electrode.

What is important here, too, is that firstly charged disturbance particles are passed on from the second trapping electrode to the third trapping electrode, before the potential at the second trapping electrode is changed in a further method step (f). Once again the direction of the third electrostatic trapping field is not changed in this case. By way of example, the potential at the second trapping electrode can thus once again be reduced in terms of its absolute value while maintaining its sign, the potential at the second trapping electrode can be set to earth potential or the polarity of the potential at the second trapping electrode can be reversed. These changes can be made stepwise or continuously or in a single step.

Analogous considerations apply in the event of another or further trapping electrode(s) being provided in addition to the third trapping electrode. By virtue of charged disturbance particles being passed on from one trapping electrode to the next trapping electrode in a stepwise manner, charged disturbance particles can be brought further away from the sensitive region of the multi-aperture arrangement in a stepwise manner, before they are ultimately trapped at the last and outermost trapping electrode, the storage trapping electrode.

In accordance with one preferred embodiment of the invention, in the normal operating mode the electrostatic field of the storage trapping electrode is shielded, such that it does not disturb the beam shaping or individual beam shaping. Various technical means can be used for this shielding. By way of example, it is possible to provide a specific electrostatic shielding or a shielding element in the region of the multi-aperture arrangement. However, it is also possible to arrange one or more of the other ring-shaped trapping electrodes or transfer trapping electrodes such that this arrangement results in a shielding effect. Other elements of the multiple particle beams system can also be used for shielding purposes, for example a beam tube, in which a charged particle beam or charged particle beams is/are guided.

In accordance with one preferred embodiment of the invention, at least one of the trapping electrodes is not used for beam shaping in the normal operating mode of the multiple particle beam system. In this embodiment, therefore, at least one additional, separate trapping electrode is provided in the region of the multi-aperture arrangement of the multiple particle beam system.

Additionally or alternatively, at least one of the trapping electrodes is used as trapping electrode in the decontamination mode and for beam shaping in the normal operating mode of the multiple particle beam system. This embodiment of the invention takes account of the fact that, besides the multi-aperture arrangement, a multi-beam generator often also comprises one or more single aperture plates having a central opening. In the normal operating mode, this singular aperture plate is used for example as a pre-aperture or as an extraction electrode and thus quite fundamentally contributes to the beam shaping. From a structural standpoint, this singular aperture plate already has all the properties that a trapping electrode is also intended to have: Specifically, it is arranged in a manner extending circumferentially around the particle- optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof. The singular aperture plate or its opening is often somewhat larger than the multiaperture region. This is therefore an elegant possibility of using the electrode or singular aperture plate that is present anyway as a trapping electrode in the decontamination mode. Of course, a singular aperture plate used in this way is only a transfer trapping electrode and not the final storage trapping electrode. This would significantly disturb operation in the normal operating mode.

In accordance with one preferred embodiment of the invention, a plurality of trapping electrodes arranged in a manner extending circumferentially around the particle-optical axis Z and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof are provided both above and below the multi-aperture arrangement relative to the particle-optical beam path. In a somewhat simplified form of expression, therefore, one group of at least two trapping electrodes is situated above the multiaperture arrangement and a further group of at least two trapping electrodes is situated below the multi-aperture arrangement. In accordance with this embodiment variant of the invention, method steps (a) to (c) are then carried out by means of the respective trapping electrodes both above the multi-aperture arrangement and below the multi-aperture arrangement. This takes account of the fact that, of course, charged disturbance particles can be present and need to be removed both on the source side, i.e. above the multi-aperture arrangement, and on the object side, i.e. below the multi-aperture arrangement.

Disturbance particles can be found in the region of the multi-aperture arrangement not just at the upper or lower surface thereof, rather disturbance particles can also migrate into the apertures in the multi-aperture arrangement, where they bring about a disturbance effect in the normal operating mode of the multiple particle microscope. In order then to remove disturbance particles from the interior of the multi-aperture arrangement, the following is provided in accordance with one embodiment of the invention: In the decontamination mode, a first extraction potential is provided at an upper multi-aperture plate of the multi-aperture arrangement and a second extraction potential is provided at a lower multi-aperture plate of the multi-aperture arrangement. In this case, the first extraction potential is different from the second extraction potential. As a result, charged disturbance particles can be virtually extracted from the interior of the multi-aperture arrangement between the upper multi-aperture plate and the lower multi-aperture plate on account of the electrostatic field applied therebetween. The upper multi-aperture plate can be the topmost multi-aperture plate of the multi-aperture arrangement; this is also advantageous, but not necessarily the case. The same applies, mutatis mutandis, to the lower or bottommost multi-aperture plate of the multi-aperture arrangement. A potential difference between the first and second extraction potentials is typically a few 100 V, e.g. 100 V or 200 V or 300 V. After charged disturbance particles have been extracted from the interior of the multi-aperture arrangement, it is then possible to continue with decontaminating the multi-aperture arrangement or the surface region of the multi-aperture arrangement, in particular by carrying out method steps (a) to (c) of the invention.

In accordance with one preferred embodiment of the invention, in the decontamination mode and in particular before step (a) the following step (g) is furthermore carried out:

Step (g) involves irradiating the multi-aperture arrangement for the electrostatic charging of disturbance particles. This irradiating can be effected in various ways. It is possible to irradiate the multi-aperture arrangement directly using charged particles. This can be done by means of a flood gun, for example. However, it is also possible for a particle source that firstly generates the individual particle beam of charged particles to be operated in a different mode or to be operated in a different way compared with a normal operating mode for the source or the emitter.

Moreover, irradiating the multi-aperture arrangement for the electrostatic charging of disturbance particles can also be effected in a different way or indirectly, specifically by choosing a different irradiation method, wherein charged particles such as electrons, for example, are first generated in a further interaction step. This includes irradiating the multiaperture arrangement with UV radiation and also irradiating the surroundings of the multiaperture arrangement with x-ray radiation. As a result, secondary electrons are generated in interaction processes, and can be used for electrostatic charging of disturbance particles.

In accordance with one preferred embodiment of the invention, the multi-aperture arrangement is irradiated both on the source side and on the object side in relation to the particle-optical beam path. This can be achieved firstly by the source for the irradiation being provided in each case on the corresponding sides of the multi-aperture arrangement. However, it is also possible to use reflection and scattering processes for irradiation of the multi-aperture arrangement on both sides.

One preferred embodiment of the invention involves inserting a beam stop into the particle- optical beam path below the multi-aperture arrangement, such that upon the beam stop being irradiated, through the multi-aperture arrangement, the irradiating charged particles are backscattered and thereby irradiate the multi-aperture arrangement on the object side. This is advantageous in particular if, for the irradiation, charged particle beams and in particular electron beams are used, in particular from the particle source already just discussed, which is installed anyway in the multiple particle beam system. The backscattering of the charged particles in the direction of the multi-aperture arrangement can optionally be supported by suitable control of one electrode or a plurality of electrodes that can be arranged between the multi-aperture arrangement and the inserted beam stop.

In accordance with a further preferred embodiment of the invention, the method comprises the following step (i) in the decontamination mode and in particular after steps (g) and (h):

Step (i) involves providing vibrations at the multi-aperture arrangement. Providing vibrations at the multi-aperture arrangement in this way makes it easier for charged disturbance particles adhering to a surface of the multi-aperture arrangement or in the interior of the multi-aperture arrangement to be detached from the multi-aperture arrangement. Actual release from a surface is more difficult than purely transferring charged disturbance particles from the multiaperture arrangement to the first trapping electrode or generally to one of the trapping electrodes. This increased amount of energy for the release process is provided by the vibrations.

The multi-aperture arrangement overall is often in the form of a tongue, that is to say that one of its lateral ends can oscillate freely. In principle, however, other configurations capable of oscillation are also conceivable. The vibrations at the multi-aperture arrangement can be provided in various ways: In accordance with one preferred embodiment of the invention, the provided vibrations comprise mechanical vibrations. It is possible, for example, to cause the multi-aperture arrangement itself to undergo corresponding vibrations. The multi-aperture arrangement is designed to be able to withstand these mechanical vibrations without being damaged. In accordance with an alternative or additional embodiment of the invention, the provided vibrations comprise sound oscillations and/or ultrasound oscillations. Up to 120 dB, no damage at all is observed at a corresponding multi-aperture arrangement. In accordance with a further preferred embodiment of the invention, the method comprises the following step in the decontamination mode and in particular after steps (g) and (h):

Step (j) involves providing an alternating electric field near the surface at the multi-aperture arrangement, wherein the direction of the electric field is oriented substantially parallel to one of the surfaces of the multi-aperture arrangement. This alternating electric field also enables a charged disturbance particle to be set in motion and in particular detached from the surface of the multi-aperture arrangement or at least set upright, such that the release can be accomplished by means of the trapping electrodes.

The various methods that support the release of charged disturbance particles can of course be combined with one another. In this case, it is advantageous in particular for a frequency at which the electric field alternates to be brought into resonance with a different vibration frequency. In this way the different methods can mutually support and reinforce one another.

It is possible for the various embodiments and variants in accordance with the first aspect of the invention to be combined with one another in full or in part, provided that no technical contradictions arise as a result.

In accordance with a second aspect of the invention, the latter relates to a multiple particle beam system, which can be for example a multi-beam particle microscope or a lithography system. The multiple particle beam system according to the invention comprises a multi-beam generator having a multi-aperture arrangement, wherein the multi-aperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multi-aperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region. In this case, in a normal operating mode of the multiple particle beam system, a multiplicity of charged individual particle beams pass through the multiplicity of apertures. In the normal operating mode, for example, a multiplicity of real or imaginary particle sources can be imaged into an object plane or sample plane. Besides the multi-aperture arrangement, the multi-beam generator can also comprise further features; by way of example, it can also comprise single or singular aperture plates that can function as global electrodes or particle lenses in the normal operating mode.

The multiple particle beam system according to the invention furthermore comprises a first trapping electrode arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis Z onto the multi-aperture arrangement in the outer region thereof. Furthermore, the multiple particle beam system comprises a second trapping electrode arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle- optical axis Z onto the multi-aperture arrangement in the outer region thereof.

Furthermore, the multiple particle beam system according to the invention comprises a mode selection device in order to operate the multiple particle beam system in the normal operating mode or in a decontamination mode, wherein the decontamination mode involves trapping charged disturbance particles from a sensitive region of the multi-aperture arrangement comprising the multi-aperture region by means of the trapping electrodes. Besides the multiaperture region, the sensitive region also comprises an adjoining region of the outer region and denotes that region in which the presence of charged disturbance particles would disadvantageously influence the beam shaping in the normal operating mode of the multiple particle beam system.

Furthermore, the multiple particle beam system according to the invention comprises a controller for controlling the multiple particle beam system. The controller can be a central controller or it can be subdivided into a plurality of modules. According to the invention, the controller is configured to provide an adjustable potential at the first trapping electrode and to provide an adjustable potential at the second trapping electrode. Adjustable here means selectable. It is possible that two predetermined potentials as per ON/OFF can be provided, but it is also possible for the potential to be continuously variable. In particular, the potential at the first trapping electrode is adjustable independently of the potential at the second trapping electrode. The two potentials are thus individually adjustable. Furthermore, the controller is configured to provide a potential, in particular earth potential, at the multi-aperture arrangement. In this case, the controller is configured to provide the same potential, and in particular earth potential, at the multi-aperture arrangement and at the electrostatic shielding element. This can also involve passive provision if the multi-aperture arrangement and the electrostatic shielding element are simply earthed. The potential only needs to be provided, it need not necessarily be provided in a variable fashion. Such a multiple particle beam system is suitable in particular for carrying out the above-described method for operating the multiple particle beam system as described in accordance with the first aspect of the invention.

The potential which is provided at the multi-aperture arrangement can be an adjustable potential. However, it is also possible for this potential not to be adjustable and for a constant potential, in particular earth potential, to be provided at the multi-aperture arrangement. As described in connection with the first aspect of the invention, what matters for the successful application of a decontamination mode is potential differences between first trapping electrode, second trapping electrode and multi-aperture arrangement, rather than the absolute values of the provided potential or the provided potentials. The trivial case in which the multi-aperture arrangement is simply earthed and needs no control at all is explicitly concomitantly encompassed by the wording of independent Patent Claim 22.

By means of the mode selection device, for example, a user of the system can switch between normal operation and decontamination operation. It is also possible, after a specific operating time of the multiple particle beam system, for a user to be reminded to temporarily operate the multiple particle beam system in a decontamination mode. Moreover, in the system it is possible to implement the practice of carrying out the decontamination mode whenever for example the multiple particle beam system, and in particular a multi-beam generator vacuum chamber, has been ventilated and the air or gas has subsequently been pumped out of the chamber again, in order once again to establish a vacuum or high vacuum in this chamber. The mode selection can then be confirmed by a user, for example by way of a switch or a selection button on a display. However, it is also possible for a mode selection device to be inherently implemented within the multiple particle beam system and for the mode selection to be effected on the basis of process parameters of the multiple particle beam system.

In accordance with one preferred embodiment of the invention, the multiple particle beam system according to the invention furthermore comprises an electrostatic shielding element arranged at a surface of the multi-aperture arrangement and in a manner projecting from this surface and extending circumferentially around the multi-aperture region of the multi-aperture arrangement. The electrostatic shielding element thus in principle has a ring structure. It can form a kind of wall at a surface of the multi-aperture arrangement. The electrostatic shielding element can be formed integrally with the surface of the multi-aperture arrangement. Besides the electrostatic shielding function, the electrostatic shielding element also forms a mechanical barrier for disturbance particles or charged disturbance particles which may move at or on the surface of the multi-aperture arrangement and thereby run the risk of penetrating into the sensitive region of the multi-aperture arrangement, which would be disturbing for the normal operating mode of the multiple particle beam system.

When the electrostatic shielding element is provided, it is furthermore the case that the second trapping electrode and the electrostatic shielding element are arranged at the same level relative to the particle-optical beam path, such that the electrostatic shielding element can shield an electrostatic field of the second shielding electrode in the normal operating mode. The second trapping electrode and the electrostatic shielding element are thus situated next to one another, which is advantageous for the shielding of the second trapping electrode. By contrast, the first trapping electrode is arranged above the second trapping electrode and above the electrostatic shielding element relative to the particle-optical beam path.

If a multiple particle beam system configured in this way is used for carrying out the method for operating a multiple particle beam system in accordance with the first aspect of the invention, then the second trapping electrode can be used as a storage trapping electrode. It is then the sole trapping electrode which, in the normal operating mode, actively generates an electrostatic field that needs to be shielded.

In a decontamination mode, therefore, for example firstly an electric field between the multiaperture arrangement and the first trapping electrode conveys a charged disturbance particle potentially present from the multi-aperture arrangement to the first trapping electrode. In a second step, the disturbance particle is conveyed from the first trapping electrode to the second trapping electrode. Afterwards, the first trapping electrode can be switched off, while the second trapping electrode remains activated as a storage trapping electrode. In the normal operating mode, therefore, an electric field of the first trapping electrode does not need to be shielded; this is necessary only for the second trapping electrode and the field thereof. The electrostatic shielding element as described is then already sufficient for this purpose.

In accordance with one preferred embodiment of the invention, the first trapping electrode is arranged nearer to the particle-optical axis than the second trapping electrode, and/or the first trapping electrode is further away from the particle-optical axis than the electrostatic shielding element. This is a particularly skilful arrangement of the first trapping electrode; it can then perform particularly well a bridge function, as it were, when charged disturbance particles are transferred from the sensitive region of the multi-aperture arrangement to the storage trapping electrode or second trapping electrode.

In accordance with one preferred embodiment of the invention, the shielding element comprises a shielding ring, the profile of which is substantially triangular. It is of course possible here for the “corners” of the profile to be rounded. The substantially triangular profile is thus wider at the surface of the multi-aperture arrangement than in an upper region. It tapers upwards, preferably continuously. The shielding element can thus comprise a wall-like or embankment-like structure, which not only enables electrostatic shielding but also forms a good mechanical barrier for any charged disturbance particle. In this case, the shielding element can comprise a height hA, for which the following holds true: 0.5 mm < hA 10.0 mm, preferably 0.5 mm < hA 5.0 mm. In accordance with one preferred embodiment of the invention, the multi-beam generator is arranged in a multi-beam generator vacuum chamber, into which an evacuable beam tube leads on the particle source side, charged particles being guided in said beam tube. In principle, it is known to guide the particle-optical beam path in a multiple particle beam system within an evacuable beam tube. Moreover, it is known, in principle, to arrange particular features or component parts of a multiple particle beam system within a specific vacuum chamber, rather than within the beam tube. These vacuum chambers or high-vacuum chambers in which a high vacuum of 10'⁹ mbar or better can be set offer more space than the beam tube itself.

In accordance with one preferred embodiment of the invention, the presence of a multi-beam generator vacuum chamber can be utilized for shielding purposes: In accordance with one preferred embodiment of the invention, the first trapping electrode and the second trapping electrode are arranged such that they are drawn back laterally behind an imaginary extension of the beam tube towards the multi-aperture arrangement. As a result, the individual particle beams of the multiple particle beam system also do not impinge on the first trapping electrode and the second trapping electrode during a normal operating mode of the multiple particle beam system. The beam tube, which is like the lateral surface of a cylinder and which is earthed, also serves as an electrostatic shielding element in the case of the arrangement in accordance with this embodiment variant of the invention.

In accordance with a further preferred embodiment of the invention, the multiple particle beam system comprises at least two further trapping electrodes which are arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multiaperture arrangement in the outer region thereof and which are arranged below the multiaperture arrangement relative to the particle-optical beam path. In this case, the controller is configured to control the further trapping electrodes and to provide a respective individually adjustable potential at each of the trapping electrodes. In this embodiment of the invention, the multiple particle beam system thus comprises a total of at least four trapping electrodes, of which two are arranged above the multi-aperture arrangement and two are arranged below the multi-aperture arrangement. In this way, it is possible to transfer and to store disturbance particles potentially present both above and below the multi-aperture arrangement by means of the trapping electrodes. In accordance with one preferred embodiment of the invention, a profile of one of the trapping electrodes is not circular and not elliptic. It is also possible for all the trapping electrodes not to be circular and not to be elliptic. The profile of the trapping electrodes is therefore not standard, but rather can be designed quite deliberately such that the electrostatic trapping field generated by means of the trapping electrodes can be deliberately shaped and influenced. It is possible, for example, to increase the field strength at the trapping electrode as a result. This allows better trapping of charged disturbance particles.

In accordance with a further preferred embodiment of the invention, the multiple particle beam system furthermore comprises a flood gun for irradiating the multi-aperture arrangement, wherein the controller is configured to control the flood gun in the decontamination mode for irradiation of the multi-aperture arrangement. In this case, the flood gun can be provided above the multi-aperture arrangement, i.e. on the source side, but it can also be provided below the multi-aperture arrangement and thus on the object side. In this case, the flood gun is arranged in such a way that it does not disturb the normal particle-optical beam path of the multiple particle beam system. By means of the flood gun, the multi-aperture arrangement can be very deliberately irradiated with charged particles such as electrons, for example, in order that charging of disturbance particles present is deliberately attained before the actual decontamination.

Additionally or alternatively, the multiple particle beam system in accordance with one embodiment variant of the invention comprises a particle source for generating a charged particle beam. In this case, the multiple particle beam system is configured to direct the charged particle beam as illuminating particle beam onto the multi-aperture arrangement. This can be achieved in a manner known per se by way of corresponding control of the particle source itself using cathode, anode, suppressor, etc. , and/or by means of corresponding control of a condenser lens system or collimation lens system. In this embodiment of the invention, furthermore, the controller is configured to control the particle source, wherein the particle source is operable in a normal operating mode and in a flooding mode, wherein in the flooding mode the particle source emits fewer charged particles and/or charged particles with lower energy than in the normal operating mode. Providing a flooding mode for the particle source thus makes it possible to dispense with a flood gun of separate nature.

In accordance with a further preferred embodiment of the invention, the multiple particle beam system comprises a UV source and/or an x-ray source for irradiating the multi-aperture arrangement. The UV source and/or an x-ray source can likewise be used for irradiating the multi-aperture arrangement, in which case this irradiation may not take place directly or else should not take place directly, but rather only indirectly. In secondary processes, charged particles such as ions or electrons, in particular secondary electrons, are generated during these irradiation processes as well, and can be used for charging disturbance particles on the multi-aperture arrangement.

In accordance with one preferred embodiment of the invention, the multiple particle beam system furthermore comprises a beam stop insertable into the particle-optical beam path in the lower region of the multi-beam generator vacuum chamber. In this case, the beam stop is configured to backscatter charged particles incident on it, such that charged particles backscattered at the beam stop can irradiate the multi-aperture arrangement on the rear side. It is possible, for example, for the beam stop to close off the lower region of the multi-beam generator vacuum chamber. It can be provided for example at or in combination with a valve at the multi-beam generator vacuum chamber.

In accordance with one preferred embodiment of the invention, the multi-aperture arrangement is in the form of a tongue and an oscillation generator is arranged at the multi-aperture arrangement. The controller is then configured to control the oscillation generator in the decontamination mode. The oscillation generator can be arranged for example at the end of the tongue in the vibration-capable region of the multi-aperture arrangement. In principle, however, it can also be arranged at a different location of the multi-aperture arrangement. Alternatively, the multi-aperture arrangement can also be formed so as to be vibration-capable in a different form. The multi-aperture arrangement can also be in a form different from tonguelike. The oscillation generator can provide mechanical vibrations or sound oscillations, for example. Both result in a mechanical movement or oscillation movement of the multi-aperture arrangement as a whole, which contributes to detaching or more easily detaching charged disturbance particles from a surface of the multi-aperture arrangement before these charged disturbance particles are trapped by means of the trapping electrodes.

In accordance with one preferred embodiment of the invention, the multiple particle beam system comprises a field generating means for generating an alternating electric field, wherein the field generating means is arranged near the surface with respect to the multi-aperture arrangement. The field generating means is preferably multipartite and can be formed for example as a capacitor, and in particular as a plate capacitor. The field generating means is configured to generate an alternating electric field oriented parallel to the surface of the multiaperture arrangement in the decontamination mode. Such field generation contributes to detaching charged disturbance particles from a surface of a multi-aperture arrangement. As a result of the influence of the alternating electric field, the bearing area of the disturbance particle can be reduced and the disturbance particle can be set upright, as it were, which facilitates the subsequent trapping of the disturbance particle by means of the trapping electrodes. In this case, the frequencies of the alternating electric field can be chosen for example such that the associated wavelength approximately corresponds to the dimensions of a disturbance particle. These are typically approximately 10'⁵ m to approximately 10'³ m.

In accordance with a further preferred embodiment of the invention, the multiple particle beam system comprises a pump system having at least one vacuum pump. Preferably, the pump system comprises more than one vacuum pump. The pump system can comprise for example a so-called turbomolecular pump and/or an ion getter pump. In this case, the pump system is connected to the multi-beam generator vacuum chamber by means of a pump line system. This pump line system can be branched or unbranched. In accordance with these embodiment variants of the invention, at least one particle trap for trapping charged disturbance particles is arranged within this pump line system, and not within the pumps themselves. There are commercially available pumps that are specified as non-particle-producing. It has nevertheless been found that individual particles that appear to originate from a pump are observable in the multi-beam generator vacuum chamber. Therefore, particle traps within the vacuum pumps or high-vacuum pumps do not always appear to be sufficient to completely eliminate disturbance particles. It is also possible for ventilation valves to contribute to disturbance particles reaching the multi-aperture arrangement; valves are not specifically specified as “non-particle- producing”. These facts are taken into account by the additional provision of particle traps within the pump line system, i.e. within pipes or lines.

In accordance with one embodiment variant of the invention, a particle trap is arranged directly upstream of the entrance to the multi-beam generator vacuum chamber. Alternatively, a particle trap can be arranged directly downstream of an exit of a vacuum pump. The former prevents any penetration of disturbance particles into the multi-beam generator vacuum chamber once the disturbance particles have already passed once into the pump line system. The second variant combats disturbance particles or traps them directly after they have arisen. Of course, it is also possible to provide a plurality of particle traps in the pump line system and to provide one particle trap directly upstream of the entrance to the multi-beam generator vacuum chamber and to arrange another particle trap directly downstream of the exit of the vacuum pump, and this can in turn be effected for all the pumps.

In accordance with one embodiment of the invention, the particle source comprises a capacitor and a flood gun for emitting charged particles, in particular electrons. The capacitor can be in the form of a plate capacitor or a cylindrical capacitor, for example. The capacitor and the flood gun are arranged such that they are successively traversed by a gas stream upon ventilation of the multi-beam generator vacuum chamber. The order of the arrangement is important here: The flood gun, in the pump line system, is arranged upstream of the capacitor in the ventilation direction of a gas stream for ventilating the multi-beam generator vacuum chamber. As a result, the ventilation gas stream traverses firstly the flood gun, and only then the capacitor. As a result, disturbance particles can first be charged by means of the flood gun and then be trapped by means of an electrostatic field of the capacitor. Furthermore, in this embodiment of the invention, the controller is configured to control and thereby operate the capacitor for providing an electric field and the flood gun for emitting charged particles during a ventilation process of the multi-beam generator vacuum chamber. The ventilation process is critical here, the venting and pumping away process being less critical. It is only when there is a comparatively high pressure in the pump line system, for example > 1 mbar, that the air stream is strong enough also actually to transport potential disturbance particles on the basis of the air stream. This pressure thus corresponds to the critical time interval during which charged disturbance particles can actually be transported into the multi-beam generator vacuum chamber by the gas stream. Afterwards, this mechanism is insignificant and it no longer takes place, de facto, at lower pressures.

In accordance with one preferred embodiment of the invention, the controller is configured to limit a gas flow through the pump line system during a critical time interval and to operate the particle trap during the critical time interval. The total time for the ventilation process is lengthened only insignificantly as a result. The ventilation of the multi-beam generator vacuum chamber could theoretically also take place faster. In that case, however, more particles are entrained and may settle in the region of the multi-aperture arrangement. Therefore, it is expedient to control the ventilation process and to limit the gas flow so that virtually as they fly past more disturbance particles can be charged and trapped by the particle trap compared with a larger gas flow or air stream. It should be noted that an analogous settling problem may thus arise, but need not arise, during a venting process. This depends on the specific arrangement of pumps and on the specific way in which the venting process is carried out. During a venting process, too, it may therefore be expedient to control the venting process and to limit the gas flow.

In accordance with a further embodiment of the invention, the particle trap comprises a first capacitor and a second capacitor. In this case, the first capacitor and the second capacitor are arranged such that they are successively traversed by a gas stream upon ventilation of the multi-beam generator vacuum chamber. In comparison with the embodiment variant just described, the flood gun is thus exchanged for a second capacitor. Once again the order in which first and second capacitors are arranged is important: The first capacitor, in the pump line system, is arranged upstream of the second capacitor in the ventilation direction of a gas stream for ventilating the multi-beam generator vacuum chamber, wherein the controller is configured to control the first capacitor for providing an alternating electric field and the second capacitor for providing a non-alternating electrostatic field. Initially neutral disturbance particles are charged in the first capacitor and are trapped in the second capacitor.

In this embodiment of the invention, too, the controller is preferably configured to limit a gas flow through the pump line system during a critical time interval of the ventilation process and/or venting process and to activate the particle trap during the critical time interval. In this case, the critical time interval is preferably that time interval which corresponds to the time interval in which the pressure in the pump line system is > 1 mbar during ventilation.

It is possible for the various embodiments and variants in accordance with the second aspect of the invention to be combined with one another in full or in part, provided that no technical contradictions arise as a result.

In accordance with a third aspect of the invention, the latter relates to a multiple particle beam system such as for example a multi-beam particle microscope or a lithography system. Unlike in accordance with the first aspect of the invention and unlike in accordance with the second aspect of the invention, a passive solution for trapping charged disturbance particles is made possible in accordance with the third aspect of the invention. In this case, it is possible, in particular, to combine the passive solution with the active solutions.

The multiple particle beam system according to the invention comprises a multi-beam generator having a multi-aperture arrangement, wherein the multi-aperture arrangement comprises a plurality of multi-aperture plates. Each of the multi-aperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multiaperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system. In this case, a first multi-aperture plate of the multi-aperture arrangement is provided, wherein this first multi-aperture plate is the first through which the multiplicity of charged particles pass. This first multi-aperture plate is therefore the topmost multi-aperture plate, which may in particular also be referred to as a pre-multi-aperture plate or as a filter plate. According to the invention, this first multi-aperture plate comprises in its outer region a trapping trench system having at least one trapping trench for trapping charged disturbance particles. The trapping trench system firstly functions as a mechanical barrier for disturbance particles situated in the trapping trench. Secondly, the trapping trench system increases the surface area of the first multi-aperture plate, which in turn increases an interaction between charged disturbance particles and the surface area, for example on account of van der Waals forces, which in turn reduces the momentum of the disturbance particles and possible movement of the disturbance particles. As a result, fewer disturbance particles pass into the sensitive region of the first multiaperture plate.

In accordance with one preferred embodiment of the invention, the first multi-aperture plate including the trapping trench system comprises a metallic layer for stopping and absorbing charged particles incident thereon. The provision of such a metallic layer is known, in principle, and according to the invention is now extended for the trapping trench system.

In the normal operating mode of the multiple particle beam system, the multi-aperture arrangement or the multi-aperture plates is/are at a defined potential, for example at earth potential. By way of example, doped silicon with or without additional metal coating can be used as material for the multi-aperture plates, and in particular for the first multi-aperture plate. This takes account of the fact that in the case of most multi-aperture arrangements, the processes used to produce them are the same as those which are customary in semiconductor production.

In accordance with one preferred embodiment of the invention, the at least one trapping trench is formed in a manner extending circumferentially around the multi-aperture region. In this case, it can be formed in a manner extending circumferentially completely or in a manner extending circumferentially with interruption. The more completely the multi-aperture region is enclosed by the at least one trapping trench, the better the trapping effect of the trapping trench.

In accordance with one preferred embodiment of the invention, the circumferentially extending trapping trench comprises one or more interruptions. The provision of such interruptions may be due to the process for producing the trapping trench. For the same reason, a trapping trench is preferably formed linearly in sections. It is possible, for example, for the multi-aperture region of the first multi-aperture plate to be surrounded by a trapping trench consisting of four linear sections. In this case, each trapping trench can be produced by means of an etching process, for example. Overall, the multi-aperture region can then be surrounded by a rectangular or square trapping trench structure. However, other overall configurations of a trapping trench system having at least one trapping trench are also possible. In accordance with one preferred embodiment of the invention, the shape of a cross section of a trapping trench is substantially rectangular, substantially triangular or substantially round- shell-shaped. Additionally or alternatively, a trapping trench is producible by means of etching technology. Anisotropic or isotropic etching methods can be used in this case. Rectangular or triangular cross-sections can most easily be produced using anisotropic etching methods, while round-shell-shaped cross-sectional shapes which approximately reproduce a circle segment can best be produced using isotropic etching methods.

In accordance with one preferred embodiment of the invention, the trapping trench system, in a direction away from the multi-aperture region, comprises a sequence of trapping trenches having at least a first inner trapping trench and a second trapping trench arranged further outwards. However, the trapping trench system can of course also comprise a third, fourth, fifth, etc. trapping trench. The sequence of trapping trenches increases the surface area of the first multi-aperture plate even further. Moreover, the movement of disturbance particles to the sensitive inner region of the first multi-aperture plate can be reduced even further by the provision of a sequence of trapping trenches: This is because a potential movement requires a multiple exchange between kinetic and potential energy, which is accompanied by losses owing to frictional forces. A movement of disturbance particles can therefore be retarded.

In accordance with one preferred embodiment of the invention, the first trapping trench comprises a first cross-section and the second trapping trench comprises a second crosssection. In this case, the shape of the first cross-section and the shape of the second crosssection are identical and the dimensions of the first cross-section and the second cross-section are likewise identical. Overall, therefore, the first trapping trench and the second trapping trench are configured identically to the greatest possible extent, and just their total length will differ from one another. Such a trapping trench system is producible in a particularly simple way.

In accordance with an alternative embodiment of the invention, the first trapping trench comprises a first cross-section and the second trapping trench comprises a second crosssection, wherein the shape of the first cross-section and the shape of the second cross-section are once again identical. The dimensions of the first cross-section and of the second crosssection are different, however, in this embodiment. It is e.g. possible for both the first trapping trench and the second trapping trench to comprise a substantially triangular cross-section, but for the first trapping trench and the second trapping trench to be formed with different depths. The variation of the dimensions of the cross-sections enables other constructional features of the multi-aperture arrangement to be taken into account in a tailored manner: In accordance with one preferred embodiment of the invention, the entire multi-aperture region of the first multi-aperture plate is arranged in a central trench and the outer region of the first multi-aperture plate is substantially not arranged in this central trench. It is then advantageous that a respective trench depth of the sequence of trapping trenches arranged in the outer region increases from the inner area outwards. This enables the first multi-aperture plate to be made stabler overall.

In accordance with one preferred embodiment of the invention, the entire multi-aperture region of the first multi-aperture plate is arranged in a central trench, wherein the following relation holds true for a depth t of the central trench: 10 pm < t < 200 pm.

In accordance with one preferred embodiment of the invention, the following relation holds true for a trench depth t of a trapping trench: 10 pm < t < 200 pm, preferably 10 pm < t < 20 pm or 10 pm < t < 18 pm. This relation can also hold true for all the trapping trenches of the trapping trench system. Firstly, the trench depth t is readily realizable in processes for producing the first multi-aperture plate. Furthermore, the trench depth is adapted to the typical size of disturbance particles, which varies in the upper nanometres range through to the order of approximately 1 pm. This kind of disturbance particles can readily be trapped in trapping trenches having the corresponding trench depth t.

Additionally or alternatively, the following relation can hold true for a maximum trench width b of a trapping trench: 8 pm < b < 12 pm.

The maximum trench width of the trapping trench is measured at that location of the trapping trench where the latter is the widest. Depending on the shape of the cross section, this may be the case at the bottom of the trapping trench, at the entrance to the trapping trench or else within the trapping trench (for example in the case of the round-shell-shaped embodiment variant). The maximum trench width b can be greater or less than the trench depth t. In principle, however, it will preferably be the case that at least in some trapping trenches, the trench depth t is greater than the maximum trench width b. Shallower trenches will be chosen primarily on account of stability considerations. In principle, deeper trapping trenches have a better trapping function. Additionally or alternatively, the following relation can hold true for a distance a between mutually adjacent trapping trenches: b/a > 1.5, preferably b/a > 2.0.

As a result, it is possible to increase the surface area of the first multi-aperture plate as significantly as possible. The distance between adjacent trapping trenches is merely not permitted to become too small, in order not to jeopardize the stability of the first multi-aperture plate.

In accordance with one preferred embodiment of the invention, the multiple particle beam system furthermore comprises a particle source for generating a charged particle beam. The multiple particle beam system is then configured to direct the charged particle beam as illuminating particle beam onto the multi-aperture arrangement. This can be achieved for example by means of a condenser lens system comprising one or more magnetic lenses or electrostatic lenses or combinations thereof. Moreover, the multiple particle beam system is configured, in a normal operating mode, to illuminate the multi-aperture region of the first multiaperture plate and substantially not to illuminate the outer region of the first multi-aperture plate. As a result, in a normal operating mode, the trapping trench system is also not illuminated and disturbance particles arranged therein are not charged further.

In accordance with a further preferred embodiment of the invention, the multiple particle beam system can comprise a pre-aperture, which trims an expanded particle beam before the latter is incident on the multi-aperture arrangement. This pre-aperture can be formed in a stepped manner, for example with exactly one step. The stepping can constitute an additional mechanical barrier for disturbance particles en route to the multi-aperture arrangement which approach the multi-aperture arrangement on the particle source side. Additionally or alternatively, an exit aperture can be provided downstream of the multi-aperture arrangement, which exit aperture is formed in a stepped manner, for example with exactly one step. This step can in turn constitute an additional mechanical barrier for disturbance particles en route to the multi-aperture arrangement which approach the multi-aperture arrangement on the object side.

The exemplary embodiments in accordance with the third aspect of the invention can in turn be combined wholly or partly with one another.

Moreover, it is possible for the exemplary embodiments in accordance with the first, in accordance with the second and in accordance with the third aspect of the invention to be combined with one another, provided that no technical contradictions whatsoever arise as a result.

The invention will be understood even better with reference to the accompanying figures, in which: Figure 1: schematically shows a multiple particle beam system;

Figure 2: schematically shows a set-up of a multi-beam generator with a multi-aperture arrangement;

Figure 3: schematically shows arrangements of a multi-beam generator in multiple particle beam systems;

Figure 4: schematically shows the set-up of a multi-aperture arrangement;

Figure 5: schematically shows a multi-aperture arrangement with trapping electrodes;

Figure 6: schematically shows a multi-aperture arrangement with trapping electrodes;

Figure 7: schematically illustrates a method for operating a multiple particle beam system;

Figure 8: schematically shows a multi-aperture arrangement with trapping electrodes and an electrostatic shielding element;

Figure 9: schematically shows method steps for operating a multiple particle beam system;

Figure 10: schematically shows further method steps for operating a multiple particle beam system;

Figure 11: schematically illustrates rear-side irradiation of a multi-aperture arrangement;

Figure 12: schematically illustrates a process of extracting charged disturbance particles from the interior of a multi-aperture arrangement;

Figure 13: schematically illustrates detachment of charged disturbance particles from a surface of a multi-aperture arrangement by means of an alternating electric field;

Figure 14: schematically shows a multi-aperture arrangement with an oscillation generator;

Figure 15: schematically shows a pump line system of a multiple particle beam system with a particle trap;

Figure 16: schematically shows a particle trap in a pump line system;

Figure 17: schematically shows an arrangement of particle traps in a pump line system;

Figure 18: schematically shows a first multi-aperture plate with a trapping trench system in a plan view;

Figure 19: schematically shows trapping trenches in a sectional view;

Figure 20: schematically shows trapping trenches in a sectional view;

Figure 21 : schematically shows trapping trenches in a sectional view;

Figure 22: schematically shows a first multi-aperture plate with a central trench and a trapping trench system in a sectional view; and

Figure 23: schematically shows a multi-aperture arrangement with a preceding preaperture and a succeeding exit aperture, which are each formed in a stepped manner. Figure 1 schematically shows a multiple particle beam system 1 in the form of a multi-beam particle microscope 1. The multi-beam particle microscope 1 comprises a beam generating apparatus 300 having a particle source 301 , for example an electron source. A divergent particle beam 309 is collimated by a sequence of condenser lenses 303.1 and 303.2 and is incident on a multi-beam particle generator 305 having a multi-aperture arrangement. The multi-beam particle generator 305 comprises a plurality of multi-aperture plates 304, 306 and a field lens 307. The multi-beam particle generator 305 generates a multiplicity of individual particle beams 3 or individual electron beams 3, which are arranged in a field, which is imaged onto a further field formed by beam spots 5 in the object plane 101. The pitch between the midpoints of apertures in a multi-aperture plate 306 can be for instance 5 pm, 100 pm and 200 pm. The diameters D of the apertures are smaller than the pitch of the midpoints of the apertures; examples of the diameters are 0.2 times, 0.4 times and 0.8 times the pitches between the midpoints of the apertures.

The multi-aperture arrangement 305 and the field lens 308 are configured to generate a multiplicity of focal points 323 of primary beams 3 in a grid arrangement on a surface 321 . The surface 321 need not be a plane surface but rather can be a spherically curved surface in order to account for an image field curvature of the subsequent particle-optical system.

The multi-beam particle microscope 1 furthermore comprises a system of electromagnetic lenses 103 and an objective lens 102, which image the beam foci 323 from the intermediate image surface 321 into the object plane 101 with reduced size. In between, the first individual particle beams 3 pass through the beam splitter 400 and a collective beam deflection system 500, by means of which the multiplicity of first individual particle beams 3 are deflected during operation and the image field is scanned. The first individual particle beams 3 incident in the object plane 101 form for example a substantially regular field, wherein pitches between adjacent incidence locations 5 can be for example 1 pm, 10 pm or 40 pm. The field formed by the incidence locations 5 can have a rectangular or hexagonal symmetry, for example.

The object 7 to be examined can be of any desired type, for instance a semiconductor wafer or a biological sample, and can comprise an arrangement of miniaturized elements or the like. The surface 15 of the object 7 is arranged in the object plane 101 of the objective lens 102. The objective lens 102 can comprise one or more electron-optical lenses. For example, it can be a magnetic objective lens and/or an electrostatic objective lens.

The primary particles 3 incident on the object 7 generate interaction products, for example secondary electrons, backscattered electrons or primary particles, which have experienced a reversal of movement for other reasons, and these interaction products emanate from the surface of the object 7 or from the first plane 101 or object plane 101. The interaction products emanating from the surface 15 of the object 7 are shaped by the objective lens 102 to form secondary particle beams 9. In the process, the secondary beams 9 pass through the beam splitter 400 downstream of the objective lens 102 and are supplied to a projection system 200. The projection system 200 comprises an imaging system 205 with projection lenses 206, 208 and 210, a contrast stop 214 and a multi-particle detector 207. Incidence locations 25 of the second individual particle beams 9 on detection regions of the multi-particle detector 207 are located with a regular pitch in a third field. Exemplary values are 10 pm, 100 pm and 200 pm.

The multi-beam particle microscope 1 furthermore comprises a computer system or control unit or controller 10, which in turn can be embodied integrally or in multipartite fashion and which is designed both to control the individual particle-optical components of the multi-beam particle microscope 1 and to evaluate and analyse the signals obtained by the multi-detector 207 or detection unit.

Further information relating to such multi-beam particle beam systems or multi-beam particle microscopes 1 and component parts used therein, such as, for instance, particle sources, multi-aperture plate and lenses, can be obtained from the international patent applications WO 2005/024881 A2, WO 2007/028595 A2, WO 2007/028596 A1 , WO 2011/124352 A1 and WO 2007/060017 A2 and the German patent applications DE 102013 016 113 A1 and DE 102013 014976 A1 , the disclosure of which is fully incorporated by reference in the present application.

Figure 2 shows by way of example a micro-optical unit 305 in the form of a multi-beam generator 305. In the illustrated example, the multi-beam generator 305 comprises a sequence with six multi-aperture plates 304, 306.1 , 306.2, 306.3, 306.4 and 310 and a global field lens 307 in the z-direction, which corresponds to the direction of propagation of the individual particle beams 3. Each of the multi-aperture plates 304, 306.1 to 306.4 and 310 comprises a multiplicity of apertures 351 , through which the multiplicity of individual particle beams 3 respectively pass. The cross section through the apertures 351 is not to scale in Figure 2.

The multiplicity of multi-aperture plates 304, 306.1 , 306.2, 306.3, 306.4 and 310 are spaced apart from one another by spacers 83.1 to 83.5. Moreover, a spacer 86 is provided between the final multi-aperture plate 310 and the global lens electrode 307. As a result of the incidence of a collimated particle or electron beam 309, the multiplicity of first individual particle beams 3 are generated during the passage through the first multi-aperture plate 304, which is also referred to as filter plate or pre-aperture plate. The pre-aperture plate 304 comprises a metal layer 99 on its beam entrance side, for stopping and absorbing the charged particles, or electrons, of the electron beam 309 that are incident thereon around the multiplicity of apertures 85. In this case, the material of the pre-aperture plate 304 is produced from a conductive material in the example shown, for example from doped silicon, and is at earth potential.

In the example shown in Figure 2, the next multi-aperture plate is a multi-stigmator plate 306.1. The multi-stigmator plate 306.1 comprises a multiplicity of four or more electrodes 82, for example eight electrodes, for each of the apertures. During the operation of the multi-beam particle microscope 1 , different voltages, for example ranging between -20 V and +20 V, can be applied to each of these electrodes and hence individually influence each individual particle beam 3. For example, it is possible with an antisymmetric voltage difference to deflect each individual particle beam 3 up to a few pm in each direction in order to pre-correct a distortion correction of the illuminating unit 100. An astigmatism pre-correction for each individual particle beam 3 can be undertaken in this way. By means of an offset voltage, each multi-pole element can additionally act as an Einzel lens.

In principle, the multi-aperture plates 306.2, 306.3 and 306.4 can be any desired trajectory correction plates with monolithic design and with a respective voltage V1, V2 and V3 applied thereto in the example shown. It is also possible that the multi-aperture plates 306.2, 306.3 and 306.4 form an Einzel lens array. Different apertures 351 in the same multi-aperture plate 306.2, 306.3 and 306.4 can have an identical design or different design, for example have different diameters, in order to take into account a field dependence of the correction in the trajectory correction of the individual particle beams 3.

The multi-aperture plate 310 is a two-layer multi-aperture plate and comprises a multiplicity of ring electrodes 79 for the multiplicity of apertures, wherein each ring electrode is configured to individually change or correct a focal position of the first individual particle beam 3 passing therethrough. In this case, the upper layer is insulated from the layer or ply with the ring electrodes 79 and is produced from a conductive material such as doped silicon, for example.

The field lens 307 comprises a ring electrode 84, to which a high voltage of for example 3 kV to 20 kV can be applied, for example 12 kV to 17 kV. In the example shown, the field lens 307 provides a global electrostatic lens field for global focussing of the multiplicity of individual particle beams 3. The micro-optical unit 305 or its multi-aperture plates shown in Figure 2 can in principle be produced by means of known production methods or by means of planar integration techniques.

Figure 3 schematically shows arrangements of a multi-beam generator 305 in multiple particle beam systems 1. In this case, Figure 3a) shows a system having a multi-beam generator 305, which comprises a multi-lens array having a plurality of multi-aperture plates 304, 306 on one side, i.e. a multi-aperture arrangement 305, and a counterelectrode or single aperture plate 307. By contrast, the system in accordance with Figure 3b comprises a multi-beam generator 305 comprising a multi-aperture arrangement 352 and a multi-deflector array 353. In this embodiment, the multi-deflector array 353 can also be regarded as part of the multi-aperture arrangement. Moreover, it is possible, of course, to replace the multi-aperture plate 352 with a plurality of multi-aperture plates; in this respect, the illustration in Figure 3 merely shows the principle of the multi-beam generators 305.

On account of the multiplicity of individual particle beams 3 being generated differently, the actual imaging with the two systems shown in Figures 3a and 3b is different as well: While in Figure 3a a multiple real image of the particle source 301 is formed by foci 323 in the plane E1 , in the embodiment variant in accordance with Figure 3b foci 323 are regarded as virtual particle sources and images of the real particle beam source 301. It holds true in both cases that the foci 323 are imaged by a particle-optical imaging in each case onto the plane E2, in which the surface of the object 7 is positioned.

It holds true in both cases moreover that the multi-beam generator 305 is illuminated by a charged particle beam after this charged particle beam has traversed a condenser lens system 303. The illumination can take place in a collimated manner (Figure 3a) or in a convergent or divergent manner (Figure 3b - the divergent case is shown). After traversing the multi-beam generator 305, the individual particle beams 3 formed each pass through a field lens system 108, which provides various degrees of freedom for adjusting imaging properties. The individual particle beams 3 subsequently pass through a beam splitter 400 before being imaged into the plane E2 at the surface of the object 7 by an objective lens system 102. The secondary beam path or secondary path for secondary beams 9 emanating from the surface of the sample 7 is not illustrated in Figure 3, for the sake of simplification.

Figure 4 schematically shows the set-up of a multi-aperture arrangement 350. In the example shown, charged particles are emitted by a particle source 301. In this case, a potential of several kV, for example +/- 20 kV, +/- 25 kV, +/- 30 kV, can be present at the particle source 301. Figure 4 then illustrates an extractor electrode, at which for example a potential of a few kV, e.g.. +/- 3 kV, +/- 4 kV or +/- 5 kV, is present. The charged particle beam 309 then traverses an electrode or stop 399, which is at earth potential in the example shown. The charged particle beam 309 subsequently traverses a condenser lens system 303.1 and 303.2, which, in the example shown, enables the charged particle beam 309 or the then illuminating particle beam 311 to divergently enter the electrostatic field of a pre-counterelectrode 398. However, this electrostatic field of the pre-counterelectrode 398 could also be entered convergently or telecentrically. The charged particle beam 311 is then incident telecentrically on a first multiaperture plate 304 having a multiplicity of round apertures, such that the multiplicity of individual particle beams 3 are formed at this first multi-aperture plate 304 as they pass through the multi-aperture plate 304. The individual particle beams 3 are shaped in the further course, specifically - in the example shown - by means of a sequence of further multi-aperture plates 306.1 , 306.2 and 306.3 and also by means of the single aperture plate or field lens 307, which constitutes a counterelectrode for drawing apart the individual particle beams 3, such that the foci 323 are further away from one another in the intermediate image plane.

The multi-aperture plates 304, 306.1 , 306.2 and 306.3 form a multi-aperture arrangement 350 in the example shown. A potential can be individually provided at the multi-aperture plates 304 and 306.3 by means of a controller 10 (not illustrated). It is also possible for earth potential to be provided at each of the multi-aperture plates 304 and 306.3. A respective individually adjustable potential is likewise able to be provided at the pre-counterelectrode 398 and at the counterelectrode 307 by means of the controller 10. While in the example shown the first multiaperture plate 304 and the final multi-aperture plate 306.3 are preferably at earth potential, a comparatively high voltage of a few kV, e.g. approximately +/-10 kV, +/- 15 kV or +/- 20 kV, is in each case present at the pre-counterelectrode 398 and at the counterelectrode 307. The sign here is given by the potential of the emitter 301 or by the charge sign of the charged particles forming the particle beams 309, 311 , 3. In the example shown, the multi-aperture plate 306.1 comprises a multiplicity of ring electrodes which are individually controllable by means of the controller 10 in order to individually adjust a focal position of the individual particle beam 3 passing therethrough. In the example shown, the multi-aperture plate 306.2 comprises individually controllable multi-pole lenses around each opening. However, it would also be possible for the sequence of multi-aperture plates 304, 306.1 , 306.2 and 306.3 of the multiaperture arrangement to be formed differently, to be shortened or to be supplemented.

A reliably and precisely operating multi-beam generator 305 is enormously important for good imaging properties of a multiple particle beam system 1. Even tiny contaminants in the form of small solid particles or dust disadvantageously affect the generation and shaping of the individual particle beams 3 and thus the imaging properties of the multiple particle beam system 1. If disturbance particles settle on the multi-beam generator 305 or on the multiaperture arrangement 350 thereof or in the vicinity of said generator/arrangement, then there is the risk of the disturbance particles being charged during operation of the multiple particle beam system 1 or even being burnt into the micro-optical unit 305. One countermeasure is therefore to provide trapping electrodes in the region of the multi-aperture arrangement 350:

Figure 5 schematically shows a multi-aperture arrangement 350 having two trapping electrodes 361 and 362. For the sake of simplification, Figure 5 illustrates an excerpt from Figure 4 for illustration purposes. However, the multi-aperture arrangement 350 could also be in a different form from that in the example shown. In the example shown, the first trapping electrode 361 is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system 1 and in a manner projected along the direction of the particle-optical axis Z onto the multi-aperture arrangement 350 in the outer region thereof. Therefore, the trapping electrode 361 is not situated in the region of the multiplicity of apertures, but rather is further away from the particle-optical axis Z than said apertures. In the example shown, the first trapping electrode 361 is ring-shaped and arranged between the precounterelectrode 398 and the first multi-aperture plate or filter plate 304. Furthermore, in Figure 5, a second trapping electrode 362 is arranged downstream of the final multi-aperture plate 306.3 and upstream of the counterelectrode or field lens 307 in relation to the particle-optical beam path. In the example shown, the second trapping electrode 362 is also a ring electrode which is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and it is arranged in a manner projected along the direction of the particle-optical axis Z onto the multi-aperture arrangement 350 in the outer region thereof. The second trapping electrode 362 - unlike the first trapping electrode 361 - is partly surrounded by an electrostatic shield 370. This is advantageous if the second trapping electrode 362 is used as a storage trapping electrode; an electrostatic field of the trapping electrode 362 can then be shielded by the shield 370 in a normal operating mode of the multiple particle beam system 1 . It is also possible to provide the first trapping electrode 361 with a further shield; in this respect, the embodiment variant illustrated in Figure 5 merely shows the principle for an arrangement of trapping electrodes 361 , 362 both above and below the multiaperture arrangement 350 relative to the particle-optical beam path. It is quite generally the case that in a decontamination mode of the multiple particle beam system, which involves trapping charged disturbance particles in a sensitive region of the multi-aperture arrangement 350, a potential is provided at the trapping electrodes 361 , 362 and said potential ensures that charged disturbance particles migrate from the multi-aperture arrangement 350 to the trapping electrodes 361 , 362 and are trapped there. The details of the method that is usable for this purpose will be discussed even more specifically further below.

Figure 6 schematically shows a further multi-aperture arrangement 350 having a multiplicity of trapping electrodes 361 , 362, 363, 364 and 365. In the example shown, the multi-beam generator 305 having the multi-aperture arrangement 350 is arranged within a multi-beam generator vacuum chamber 380, which is only partly indicated in Figure 6. An illuminating particle beam 311 passes through an earthed beam tube 371 into the multi-beam generator vacuum chamber 380, where it irradiates the multi-aperture arrangement 350 for the purpose of forming and shaping the individual particle beams 3. Specifically, in this case substantially the multi-aperture region 350 having the multiplicity of apertures is irradiated, and the outer region 356 around the multi-aperture region 355 is substantially not irradiated, but could also be irradiated at least in part, given appropriate expansion of the illuminating particle beam 311. The multi-aperture region 355 and directly adjoining regions of the outer region 356 form the sensitive region of the multi-aperture arrangement 350. In this sensitive region, disturbance particles, and in particular charged disturbance particles 701 , 702, have a negative influence on the beam shaping. In the example shown, one exemplary disturbance particle 701 is situated on a top side of the multi-aperture arrangement 350 and a further disturbance particle 702 is situated on the rear side of the multi-aperture arrangement 350. For the purpose of trapping these disturbance particles 701 and 702, a plurality of trapping electrodes 361 , 362,

363 and also 364 and 365 are now provided both above the multi-aperture arrangement 350 and also below the multi-aperture arrangement 350. All the trapping electrodes 361 , 362, 363,

364 and 365 are arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system 1 and in a manner projected along the direction of the particle-optical axis Z onto the multi-aperture arrangement 350 in the outer region 356 thereof and are additionally drawn back laterally behind an imaginary extension of the beam tube 371 to the multi-aperture arrangement 350. The trapping electrodes 361 and 363 are arranged at the same level z2 in the example shown. The second trapping electrode 362 is provided at the level z1 and thus nearer to the surface of the multi-aperture arrangement 350. In this case, the diameter of the first trapping electrode 361 is smaller than the diameter of the second trapping electrode 362, which in turn is smaller than the diameter of the third trapping electrode 363. In the example shown, by means of control - which will be described in more specific detail - of the trapping electrodes 361 , 362 and 363 and of the multi-aperture arrangement 350, it is possible to move a charged disturbance particle 701 progressively firstly to the first trapping electrode 361 , then to the second trapping electrode 362 and then to the third trapping electrode 363 and also to store it at the third trapping electrode 363 during a normal operating mode of the multiple particle beam system 1. That trapping electrode 363 which is the furthest away from the particle-optical axis Z is thus used as a storage trapping electrode 363. Moreover, the specific arrangement of the other two storage electrodes 361 and 362 in Figure 6 makes it possible to shield an electrostatic potential of the third trapping electrode 363 by way of the two trapping electrodes 361 and 362 in the normal operating mode. The earthed beam tube 371 , which is ring-shaped, can likewise serve as an additional shield.

In the example shown, two trapping electrodes 364 and 365 are arranged below the multiaperture arrangement 350. These trapping electrodes have no beam-shaping function whatsoever in a normal operating mode of the multiple particle beam system 1. By contrast, the counterelectrode 307 - as described in association with Figure 4 - is used for beam shaping in the normal operating mode. In the decontamination mode, by contrast, this counterelectrode 307 can likewise be used as a trapping electrode owing to its ring-shaped or circumferentially extending character around the particle-optical axis Z. A caveat is that it is not permanently considered as a storage trapping electrode. In a decontamination mode of the multiple particle beam system 1 , it is therefore possible to move a charged disturbance particle 702 firstly to the counterelectrode 307 and afterwards first to the trapping electrode 364 and then to the trapping electrode 365. The disturbance particle 702 can then be stored at the trapping electrode 365 as storage trapping electrode 365.

In an analogous manner, a pre-counterelectrode 398, as described in Figure 4, could also be used as a trapping electrode, for example instead of the first trapping electrode 361.

Figure 7 schematically illustrates a method for operating a multiple particle beam system 1. The initial method step S1 involves firstly providing the multiple particle beam system 1 having a multi-aperture arrangement 350 and, in the example described, having 3 trapping electrodes, for example the trapping electrodes 361 , 362 and 363, as illustrated in Figure 6. The multiaperture arrangement 350 comprises a plurality of multi-aperture plates, wherein each of the multi-aperture plates 304, 306 comprises a multi-aperture region 355 having a multiplicity of apertures 85, 351 and an outer region 356 around the multi-aperture region 355. It holds true once again that in a normal operating mode of the multiple particle beam system 1 , a multiplicity of charged individual particle beams pass through the multiplicity of apertures 85, 351. A first trapping electrode 361 is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system 1 and in a manner projected along the direction of the particle-optical axis Z onto the multi-aperture arrangement 350 in the outer region 356 thereof. The same applies to the second trapping electrode 362 and also the third trapping electrode 363. The second trapping electrode is arranged further away from the particle-optical axis Z than the first trapping electrode, and the third trapping electrode in turn is arranged further away from the particle-optical axis Z than the second trapping electrode.

In the example described, an optional method step S2 involves irradiating the multi-aperture arrangement 350 for the electrostatic charging of disturbance particles 701 , 702. For this purpose, it is possible, for example, to use a flood gun for irradiating the multi-aperture arrangement 350 and to control this flood gun in the decontamination mode for irradiation of the multi-aperture arrangement 350. However, it is also possible to use the particle source 301 - present anyway - of the multiple particle beam system 1 for this process of charging disturbance particles. In this case, the controller 10 can be configured to control or to operate the particle source 301 in a normal operating mode and in a flooding mode, wherein in the flooding mode the particle source 301 emits fewer charged particles and/or charged particles with lower energy than in the normal operating mode. Additionally or alternatively, it is also possible, for the irradiating in step S2, to use a UV source and/or an x-ray source for irradiating the multi-aperture arrangement 350, wherein for example secondary electrons are generated by means of secondary processes and can in turn irradiate the multi-aperture arrangement 350. Overall, it is advantageous if, during the irradiation in accordance with step S2, the multiaperture arrangement 350 is irradiated both on the source side and on the object side in relation to the particle-optical beam path.

A further method step S3 then involves operating the multiple particle beam system 1 in a decontamination mode, wherein in step S3 firstly the same potential is provided at the multiaperture arrangement 350, at the first trapping electrode 361 , at the second trapping electrode 362 and at the third trapping electrode 363. This potential can be earth potential.

In method step S4, the potential at the first trapping electrode 361 is changed by means of the controller, as a result of which a first electrostatic trapping field is generated between the first trapping electrode 361 and the multi-aperture arrangement 350. A charged disturbance particle 701 can therefore migrate from the multi-aperture arrangement 350 to the first trapping electrode 361.

In step S5, the potential at the second trapping electrode 362 is changed and a second electrostatic trapping field is generated between the second trapping electrode 362 and the first trapping electrode. In this case, the second electrostatic trapping field is stronger than the first electrostatic trapping field. Consequently, the charged disturbance particle 701 can migrate from the first trapping electrode 361 to the second trapping electrode 362. In method step S6, in the example shown, the potential of the first trapping electrode 361 is changed, wherein this change does not result in the direction of the second electrostatic trapping field being changed. This change can take place for example by virtue of the fact that the potential at the first trapping electrode 361 is reduced in terms of its absolute value while maintaining its sign, the potential at the first trapping electrode can be set to earth potential or the polarity of the potential at the first trapping electrode 361 can be reversed. The simplest way is to (re)set the potential at the first trapping electrode 361 to earth potential. The change in the potential at the first trapping electrode 361 takes place only when the charged disturbance particle 701 has definitely been moved from the first trapping electrode 361 to the second trapping electrode 362; thus the disturbance particle 701 is not lost again from the first trapping electrode 361 as a result of a change in the potential at said first trapping electrode. A reliable transfer of the disturbance particle 701 is thus ensured.

In method step S7, the potential at the third trapping electrode 363 is changed and a third electrostatic trapping field is generated between the third trapping electrode 363 and the second trapping electrode 362. In this case, the third electrostatic trapping field is in turn stronger than the second electrostatic trapping field, such that the charged disturbance particle 701 can migrate from the second trapping electrode 362 to the third trapping electrode 363.

A method step S8 then involves changing the potential at the second trapping electrode 362, wherein the direction of the third electrostatic trapping field is not changed as a result. It is once again possible to reduce the potential at the second trapping electrode 362 in terms of its absolute value while maintaining its sign, to set the potential at the second trapping electrode to earth potential or to reverse the polarity of the potential at the second trapping electrode 362. The simplest way is to set the potential at the second trapping electrode to earth potential again.

Optionally, it is also possible to change the potential present at the second trapping electrode 362, in particular to decrease said potential, between method steps S5 and S6. As a result, the potential applied to the third trapping electrode 363 in step S6 can be chosen such that the third electrostatic trapping field is indeed made stronger than the second electrostatic trapping field, but overall need only be made as high as the second electrostatic trapping field was, too, at the beginning of its formation in method step S5. As a result, it is possible to pass on charged disturbance particles 701 progressively from one trapping electrode to the next trapping electrode, without the electrostatic trapping field required for this having to become ever stronger. A method step S9 then involves operating the multiple particle beam system 1 in its normal operating mode, wherein the multiplicity of charged individual particle beams 3 pass through the multi-aperture arrangement 350 and they are imaged in particular - as illustrated for example in Figures 1 and 3 - onto an object plane 101. In this case, in method step S9, in the normal operating mode the same potential is provided at the multi-aperture arrangement 350 and also at the first trapping electrode 361 and at the second trapping electrode 362. By contrast, a potential provided at the third trapping electrode 363 is different from that provided at the multi-aperture arrangement 350. In this way, in the normal operating mode, charged disturbance particles 701 can remain at this third trapping electrode 363, which constitutes a storage trapping electrode 363 in the example described. It is preferably the case that earth potential is present at the first trapping electrode 361 , at the second trapping electrode 362 and at at least the multi-aperture plate 304 of the multi-aperture arrangement that is the nearest to the trapping electrodes. In this way, the method according to the invention is able to be carried out in a particularly simple manner.

In an analogous way, the described method for operating a multiple particle beam system 1 can also be carried out for a plurality of trapping electrodes which are not arranged above the multi-aperture arrangement 350, but rather below the multi-aperture arrangement 350 (cf. the illustration in Figure 6, for example). In this context, it is also possible for electrodes which are provided near the multi-aperture arrangement 350 anyway and which serve for beam shaping in the normal operating mode to be used as trapping electrodes in the decontamination mode.

Depending on the size of disturbance particles and/or depending on the charging state of disturbance particles 701 , it may be difficult, under certain circumstances, to remove charged disturbance particles 701 from a surface of the multi-aperture arrangement 350 directly by means of electrostatic trapping fields. In accordance with one preferred embodiment of the invention, it is therefore proposed to carry out an additional method step for first detaching or partially detaching charged disturbance particles 701 from the surface of the multi-aperture arrangement 350. This method step for detaching the disturbance particles 701 can be realized in various ways: It is possible, for example, to provide vibrations at the multi-aperture arrangement 350. These vibrations can comprise mechanical vibrations, for example, or they can comprise sound or ultrasound oscillations. An additional or alternative possibility consists in providing an alternating electric field near the surface at the multi-aperture arrangement 350, wherein the direction of the electric field is oriented parallel or antiparallel to one of the surfaces of the multi-aperture arrangement. Such an alternating electric field makes it possible that a charged disturbance particle 701 at the surface of the multi-aperture arrangement 350, if not completely detached, is nevertheless put upright in this way, which facilitates detachment by means of the electrostatic trapping field.

Figure 8 schematically shows a multi-aperture arrangement 350 having trapping electrodes 361 , 362 and an electrostatic shielding element 372. The shown multi-aperture arrangement 350, the trapping electrodes 361 , 362 and the electrostatic shielding element 372 can once again be part of a multiple particle beam system 1 equipped with a mode selection device in order to operate the multiple particle beam system 1 in a normal operating mode and in a decontamination mode, as has already been described a number of times above. In Figure 8, the first trapping electrode 361 is arranged as first trapping electrode 361 downstream of the opening of the beam tube 371 with respect to a multi-beam generator vacuum chamber 380. The trapping electrode 361 is drawn back laterally behind an imaginary extension of the beam tube 371 towards the multi-aperture arrangement 350. The first trapping electrode 361 is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system 1 and in a manner projected along the direction of the particle- optical axis Z onto the multi-aperture arrangement 350 in the outer region 356 thereof. In the example shown, the first trapping electrode 361 is configured as a ring electrode and has a diameter D1. In the example shown, the second trapping electrode 362 is likewise in the form of a ring electrode and has a larger diameter D2 than the first trapping electrode 361 . Moreover, the second trapping electrode 362 is provided very near to the multi-aperture arrangement 350. In the sensitive region of the multi-aperture arrangement 350, i.e. in the multi-aperture region 355 or near the multi-aperture region 355, charged disturbance particles 701 and 702 and 703 are depicted in Figure 8. In the example shown, the electrostatic shielding element 372 is arranged between these disturbance particles 701 , 702, 703 and the second trapping electrode 362. Specifically, the electrostatic shielding element 372 is arranged at a surface of the multi-aperture arrangement and in a manner projecting from this surface and extending circumferentially around the multi-aperture region 355 of the multi-aperture arrangement 350. The electrostatic shielding element 372 provides a ring-like or wall-like structure which, on account of its arrangement, is suitable for shielding an electrostatic trapping field at the second trapping electrode 362 during operation of the multiple particle beam system 1 in the normal operating mode. In this case, the second trapping electrode 362 and the electrostatic shielding element 372 are arranged substantially at the same level relative to the particle-optical beam path. In this case, in the example shown, the electrostatic shielding element 372 is somewhat higher or extends higher than the second trapping electrode 362. By contrast, it is not the case that the electrostatic shielding element 372 would be made so high that it would additionally shield the first trapping electrode 361. Instead, the basic concept is to choose the arrangement of the two trapping electrodes 361 , 362 and of the electrostatic shielding element such that in a stepwise manner charged disturbance particles 701 , 702 can be transferred firstly from the multi-aperture arrangement 350 or else from the electrostatic shielding element 372 firstly to the first trapping electrode 361 and can subsequently be transferred further to the second trapping electrode 362. The latter serves as a storage trapping electrode 362 in the normal operating mode of the multiple particle beam system 1 and can be shielded by the electrostatic shielding element 372. In the normal operating mode, the first trapping electrode 361 can simply be switched off or set to earth potential, and so no electrostatic field or disturbance field exists there. In this respect, the first trapping electrode 361 is arranged above the second trapping electrode 362 and above the electrostatic shielding element 372 relative to the particle-optical beam path.

In the decontamination mode and also in the normal operating mode, the same potential, in particular earth potential, is present at the electrostatic shielding element 372 and at the multiaperture arrangement 350 or at the surface thereof. It is also possible to form the shielding element 372 integrally with the multi-aperture arrangement 350 itself. In the example shown, the shielding element 372 is in the form of a shielding ring, the profile of which is substantially triangular. In this case, corners of the substantially triangular profile are preferably rounded. The substantially triangular profile has two advantages: Firstly, it is simple to produce; secondly, the shape of the profile of the electrostatic shielding element 372 enables shaping of the electrostatic field formed between this shielding element 372 and the first trapping electrode 361 in the decontamination mode, and it is possible to provide higher field strengths for the trapping process on account of the shaping. However, shapings other than a substantially triangular shaping for the electrostatic shielding element 372 are also possible.

Figure 9 schematically shows method steps for operating a multiple particle beam system 1 in a decontamination mode. In this case, the detailed illustration from Figure 8 is replaced with a more schematic manner of illustration. Figure 9a shows an initial method step, in which the same potential, for example earth potential, is provided at the multi-aperture arrangement 350 including the electrostatic shield 372 and likewise at the first trapping electrode 361 and at the second trapping electrode 362.

Figure 9b illustrates the situation with a changed potential at the first trapping electrode 361 : A first electrostatic trapping field is formed between the surface of the multi-aperture arrangement 350 and the first trapping electrode 361 and charged disturbance particles 702, 703 move from the surface of the multi-aperture arrangement 350 to the first trapping electrode 361. The same analogously applies to a transfer of a charged disturbance particle 701 from the electrostatic shielding element 372 to the first trapping electrode 361. Figure 10a shows the situation after a potential at the second trapping electrode 362 has also been changed and a second electrostatic trapping field has been provided between the second trapping electrode 362 and the first trapping electrode 361. In this case, this second electrostatic trapping field is stronger than the first electrostatic trapping field, such that charged disturbance particles 701 , 702, 703 migrate from the first trapping electrode 361 to the second trapping electrode 362. Figure 10b shows the end of this migration process: All the charged disturbance particles 701 , 702, 703 are now situated at the second trapping electrode

362, which also serves as a storage trapping electrode. After the transfer of the charged disturbance particles 701 , 702, 703 to the second trapping electrode 362 has been concluded, the potential at the first trapping electrode 361 can be changed and in particular switched off or set to earth potential. This is the simplest embodiment variant. Nevertheless, the potential at the first trapping electrode 361 can also just be reduced in terms of its absolute value while maintaining its sign or the polarity of the potential can be reversed. Of course, it is also possible to provide one or further trapping electrodes above the multi-aperture arrangement 350 which have a larger diameter D than the trapping electrodes 361 , 362 and are thus arranged further away from the particle-optical axis Z.

Figure 11 schematically shows a further exemplary embodiment of the invention. The illustration shows, in principle, an extension of the multi-aperture arrangement 350 from Figures 8, 9 and 10: In the embodiment variant illustrated in Figure 11 , it is the case that three further trapping electrodes 363, 364 and 365 are arranged below the multi-aperture arrangement 350 relative to the particle-optical beam path, wherein the controller 10 of the multiple particle beam system 1 is configured also to control these further trapping electrodes

363, 364, 365 and to provide a respective individually adjustable potential for the trapping electrodes. These trapping electrodes 363, 364 and 365 serve to trap or to store charged disturbance particles 704, 705 and 706 situated at an underside of the multi-aperture arrangement 350. Before a transfer of the charged disturbance particles 704, 705 and 706 to the trapping electrodes 363, 364 and 365 then takes place in the decontamination mode in accordance with the method that has already been described a number of times, for the purpose of deliberately charging the disturbance particles 704, 705, 706 it is possible for the disturbance particles 704, 705, 706 to be irradiated, specifically on the underside of the multiaperture arrangement 350: For this purpose, the multiple particle beam system 1 , in the particle-optical beam path, comprises an insertable beam stop 390 in the lower region of the multi-beam generator vacuum chamber 380. This beam stop 390 is configured to backscatter charged particles, in particular electrons, incident on it, such that charged particles backscattered at the beam stop 390 can irradiate the multi-aperture arrangement 350 on the rear side. This is indicated by the arrows 313 proceeding from the beam stop 390. Moreover, it is the case that not only primarily backscattered particles or electrons but also secondarily backscattered particles or electrons can be used for charging purposes. This is indicated by arrows 314 in Figure 11 , while the primarily backscattered particles are indicated by the arrows 313. Overall, this irradiation process within the multi-beam generator vacuum chamber 380 results in the occurrence of many charged particles or electrons, such that disturbance particles 704, 705, 706 possibly present can be comprehensively charged. This concerns firstly the rear side of the multi-aperture arrangement 350, but if appropriate also wall regions of the multi-beam generator vacuum chamber 380.

In this case, the source for the irradiation process can be identical with the particle source 301 of the multiple particle beam system. It is possible, for example, to operate the particle source 301 in a normal operating mode and in a flooding mode, wherein the particle source 301 emits fewer charged particles and/or charged particles with lower energy, for example electrons, than in the normal operating mode. This is also indicated thus by the particle beam 312 in Figure 11. Alternatively, it is possible for the multiple particle beam system to be provided with a further particle source, such as a flood gun, for example, which is controlled by means of the controller 10 in order to ensure irradiation of the multi-aperture arrangement 350 in the decontamination mode. The flood gun can be arranged for example in the multi-beam generator vacuum chamber 380 (not illustrated).

Additionally or alternatively, it is also possible to arrange a UV source and/or an x-ray source for irradiating the multi-aperture arrangement within the multi-beam generator vacuum chamber 380 (neither being illustrated). The basic concept here is that in these irradiation processes, too, charged particles are generated by way of scattering processes and secondary processes, and then traverse the interior of the multi-beam generator vacuum chamber 380 and enable charging of disturbance particles 704, 705, 706. If an x-ray source is used for the irradiating, it is preferably a low-energy x-ray source, for example with energies of around 100 eV, in order that the multi-aperture arrangement is not damaged by x-ray radiation. Moreover, an exposure time of the multi-aperture arrangement with low-energy x-ray radiation is only short, which likewise minimizes potential residual damage to the multi-aperture arrangement.

Of course, it is possible that disturbance particles 701 , 702 may exist not only at a first plate of the multi-aperture arrangement and at a last plate of the multi-aperture arrangement 350, but also that they may exist within the apertures of the multi-aperture arrangement 350. A corresponding example is illustrated in Figure 12. In the example shown, the multi-aperture arrangement 350 comprises a first multi-aperture plate 304 and a final multi-aperture plate 306.2. Arranged in between is a further multi-aperture plate 306.1 , where ring electrodes are respectively provided around the apertures. Voltage can be individually applied to these ring electrodes 82 during normal operation of the multiple particle beam system 1. By contrast, the actual plate 306.1 is at a different potential, for example earth potential. In the example shown, the first multi-aperture plate 304 is simultaneously the filter plate; it is electrically conductive. The final multi-aperture plate 306.2 is likewise electrically conductive in the example shown. It is thus possible to deliberately provide a first or a second extraction potential at the first multiaperture plate 304 and at the final multi-aperture plate 306.2, respectively, by means of the controller 10 (not illustrated), wherein the first extraction potential and the second extraction potential are different. In the example shown, a potential of -100 V is present at the first multiaperture plate 304, and a potential of +100 V is present at the final multi-aperture plate 306.2. In between, earth potential is present at the multi-aperture plate 306.1. These potentials make it possible to provide an extraction potential, with the effect that charged disturbance particles

701 , 702 can be extracted from the interior of the multi-aperture arrangement 350 on account of the applied electrostatic field. In the case of negatively charged disturbance particles 701 ,

702, these migrate firstly to the final multi-aperture plate 306.2 and from there, in the course of the decontamination method described, firstly to the first trapping electrode 307, which is identical with a counterelectrode 307 in the normal operating mode in the example shown. Afterwards, charged disturbance particles 701 , 702 can be transferred progressively to the second trapping electrode 362, then to the third trapping electrode 363 and finally to the fourth trapping electrode 364. In the normal operating mode, preferably only the fourth trapping electrode 364 is switched on. On account of its position at the level of the second trapping electrode 362 and the respective ring-shaped embodiments of all the trapping electrodes 362,

363, 364, the electrostatic field of the fourth trapping electrode 364 is shielded during normal operation.

Figure 12 additionally illustrates that by virtue of the displaceable beam stop 390, charging with charged particles can also take place in the interior of the multi-aperture arrangement 350: As a result of flooding of the region around the multi-aperture arrangement 350, disturbance particles 701 , 702 and 703 can be correspondingly charged by means of the backscattered particles on the particle trajectories 313.1 , 313.2 and 313.3.

In the exemplary embodiments shown, the profiles of the trapping electrodes 361 , 362, 363,

364, 365 are either circular or elliptic. However, it is also possible for the profile of the trapping electrodes to be chosen explicitly not to be circular and not to be elliptic. The shape and strength of electrostatic fields of the trapping electrodes 361 , 362, 363, 364, 365 can be deliberately influenced as a result. Figure 13 schematically illustrates detachment of charged disturbance particles 701 from a surface 352 of a multi-aperture arrangement 350 by means of an alternating electric field. Figure 13a illustrates the situation at the beginning of the detachment process: A disturbance particle 701 is negatively charged and bears by its longitudinal side on the surface 352 of the multi-aperture arrangement 350. The bearing area is thus large. Van der Waals forces between the charged disturbance particle 701 and the surface 352 are therefore likewise large. Providing an alternating electric field EA, represented by the double-headed arrow in Figure 13a, enables the contact area between the disturbance particle 701 and the surface 352 to be reduced: For this purpose, an alternating electric field is generated near the surface with respect to the multi-aperture arrangement 350, and is oriented parallel to the surface of the multi-aperture arrangement 350. By contrast, an electrostatic trapping field ED is nonalternating and directed away from the surface 352.

Figure 13b illustrates the effect of the alternating electric field EA after some time: As a result of shaking at the charged disturbance particle 701 , the disturbance particle 701 has been put upright and its bearing area or contact area with the surface 352 of the multi-aperture arrangement 350 is reduced. Consequently, the frictional forces and van der Waals forces between the charged disturbance particle 701 and the multi-aperture arrangement 350 are also reduced, such that the charged disturbance particle 701 can ultimately be removed from the surface 352 of the multi-aperture arrangement 350 by means of a correspondingly chosen electrostatic trapping field ED.

Figure 14 schematically shows a further form of realization for the facilitated detachment of a disturbance particle 701 from a surface of the multi-aperture arrangement 350 or generally from the multi-aperture arrangement 350: In Figure 14, a multi-aperture arrangement 350 is formed like a tongue. That means that a mount 386 is provided only at one side of the multiaperture arrangement 350. The opposite end of the multi-aperture arrangement 350 with respect to the mount 386 is freely movable, in principle, and can oscillate. In order to detach charged disturbance particles, then, an oscillation generator 385 is arranged at the free end of the tongue of the multi-aperture arrangement 350 in the example shown. The controller 10 (not illustrated) is configured to control the oscillation generator 385 in the decontamination mode and thus to cause the multi-aperture arrangement 350 to vibrate. In this way, charged disturbance particles 701 adhering to the multi-aperture arrangement 350 are also shaken and can therefore be detached from the multi-aperture arrangement 350 in a decontamination mode of the multiple particle beam system 1. The oscillation generator 385 can provide mechanical vibrations and/or sound oscillations. In the normal operating mode, a multiple particle beam system 1 according to the invention preferably operates in a high vacuum, that is to say in a pressure range of 10'⁹ mbar or better. Nevertheless, it has been found that charged disturbance particles 701 can pose a problem for this kind of multiple particle beam system 1. In order to eliminate this problem, various measures have been described above for carrying out a decontamination of the multi-beam generator vacuum chamber 380 or the multi-aperture arrangement 350. A further concept, however, involves not even allowing disturbance particles to penetrate into the multi-beam generator vacuum chamber 380 in the first place or at least further reducing their number by means of further measures. Pumps suitable for generating a high vacuum often have the specification “non-particle-forming”. All the same, however, corresponding disturbance particles are apparently nevertheless present again and again in the region of pumps. It would therefore appear not to be sufficient to completely rely on particle traps provided in a manner inherent to pumps. Therefore, a further or alternative approach of the invention is also to develop a pump line system 900 for a multiple particle beam system 1 :

In accordance with this embodiment variant, a multiple particle beam system 1 furthermore comprises a pump system having at least one vacuum pump 901 , 902, said pump system being connected to the multi-beam generator vacuum chamber 380 by means of a pump line system 390. In this case, a particle trap 910 for trapping charged disturbance particles is arranged within the pump line system 900. It should be emphasized once again that this particle trap 910 is arranged independently of or outside the pumps 901 and 902. This therefore actually constitutes an improvement of the pump line system 900.

Figure 15 schematically shows a pump line system 900 of a multiple particle beam system 1 with a particle trap 910: The pump line system 900 branches downstream of the exit from the multi-beam generator vacuum chamber. One branch leads to the ion getter pump 901 and a further branch leads to the turbo pump 902. Furthermore, in the pump line system 900, a possible disturbance particle source such as a chamber 903 is arranged, serving for example for storage or mounting of a sample for the multiple particle beam system. A ventilation valve 904 is arranged between the chamber 903 and the multi-beam generator vacuum chamber 380. Ventilation valves are normally not explicitly classified as “non-particle-forming”. In this respect, a ventilation valve 904 constitutes a possible source of disturbance particles.

In the embodiment variant illustrated in Figure 15, a particle trap 910 is then arranged directly upstream of the entrance to the multi-beam generator vacuum chamber 380. Said particle trap is intended to prevent charged disturbance particles 701 from passing into the multi-beam generator vacuum chamber 380 at all during a ventilation process.

The particle trap itself can be realized in various ways. Figure 16 schematically shows a particle trap 910 in two different embodiment variants. In Figure 16, the pattern-hatched background is in each case due to the fact that the particle trap 910 is arranged within the pump line system 900. Figure 16a shows one embodiment of a particle trap 910 having a capacitor 911a, 911b and having a flood gun 912 configured to emit charged particles 3, in particular electrons. This emission is indicated by the circular elements having the minus sign in the centre; the arrow indicates the direction of movement of the electrons emitted by the flood gun 912. If a disturbance particle 701 that is initially uncharged then passes the flood gun 912 or through the particle beam emitted by the latter, the disturbance particle 701 is charged negatively in the example shown. If it subsequently moves into the electrostatic field of the capacitor having the two plates 911a, 911b, the charged disturbance particle 701 settles on the capacitor plate 911 b that is positively charged. The charged disturbance particle 711 is thus trapped there. Both the flood gun 912 and the capacitor 911a, 911 b can be controlled by the controller 10 during a ventilation process of the multi-beam generator vacuum chamber 380.

Figure 16b shows an alternative embodiment of a particle trap 910 having a first capacitor 913a, 913b and a second capacitor 911a, 911b. In the ventilation direction of a gas stream for ventilating the multi-beam generator vacuum chamber 380, the first capacitor 313a, 313b is arranged upstream of the second capacitor 911a, 911 b. An alternating electric field is applied to the first capacitor 913a, 913b by means of the controller during the ventilation process, said electric field causing charging at a disturbance particle 701 traversing this field. After travelling through the alternating electric field, the now charged disturbance particle 701 can once again be trapped by a non-alternating electrostatic field of the second capacitor 911a, 911b and settles on one of the plates, here 911b.

It should be noted that the configuration of the two capacitors 911 , 913 as plate capacitors has been chosen merely by way of example. The configuration could for example also be implemented as a cylindrical capacitor or in some other way.

In both embodiment variants in accordance with Figure 16, the controller 10 of the multiple particle beam system is configured to limit a gas flow through the pump line system 900 during a critical time interval of the ventilation process and/or a venting process and thus to activate the particle trap 910 during the critical time interval. The critical time interval preferably corresponds to the time interval in which the pressure in the pump line system is greater than or equal to 1 mbar during ventilation. With a smaller gas or air stream, it is unlikely that disturbance particles 701 will still be moved by this gas stream or air stream. In this respect, it is possible to limit the active time of the particle trap 910 to a specific, critical time interval.

It should be emphasized that use can be made of the particle trap 910 in the pump line system 900 in association with the above-described invention, in which a multiple particle beam system 1 is operated firstly in a decontamination mode and secondly in a normal operating mode. However, it is also possible to provide a particle trap in a pump line system 900 for a different multiple particle beam system.

Figure 17 schematically shows an alternative arrangement of particle traps 910 in a pump line system 900. Unlike in the example in accordance with Figure 15, a particle trap 910 is not arranged directly upstream of the entrance to the multi-beam generator vacuum chamber 380, rather respective particle traps 910 are arranged directly downstream of an exit of a vacuum chamber 901 and directly downstream of an exit of a potential disturbance particle source such as the valve 904, for example. Other arrangements of particle traps 910 are also possible. Moreover, these particle traps 910 can once again be configured in various ways, as has already been described for example in association with Figure 16.

A further embodiment of the invention is described below, which makes it possible to trap and detain disturbance particles or charged disturbance particles in a particularly simple manner. This solution - in contrast to the described solutions with trapping electrodes - is a passive solution. For trapping or detaining disturbance particles, and in particular charged disturbance particles 701 , provision is made of a trapping trench system having at least one trapping trench for trapping charged disturbance particles 701.

Figure 18 schematically shows by way of example one embodiment variant of this aspect of the invention: Specifically, Figure 18 schematically shows a multi-aperture arrangement 350 in a plan view. The illustration shows a first multi-aperture plate 304 in the particle-optical beam path. This first multi-aperture plate is normally identical with the so-called filter plate, and the first individual particle beams of a multiple particle beam system are first formed upon incidence on or passage through this multi-aperture plate 304 with its multiplicity of apertures. In the example shown, the first multi-aperture plate 304 comprises a multi-aperture region having a multiplicity of apertures, which are merely indicated schematically as pattern filling in the form of the dotted region in Figure 18. The arrangement of the multiplicity of apertures in the multi-aperture region 355 can be designed in various ways; by way of example, hexagonal arrangements of apertures can be provided. However, it is also possible to provide rectangular grids or an overall circular arrangement of apertures in the multi-aperture region. Besides this multi-aperture region 355, the first multi-aperture plate 304 comprises an outer region 356 arranged around the multi-aperture region 355. A trapping trench system having at least one trapping trench is provided in this outer region 356. In the example shown, the trapping trench system comprises three trapping trenches 381 , 382 and 383 formed substantially in a manner extending circumferentially around the multi-aperture region 356. In the example shown, each of the trapping trenches 381 , 382, 383 comprises four interruptions arranged in each case in corner regions. In this case, the trapping trenches 381 , 382, 383 are formed linearly in sections. By way of example, the trapping trench 381 forming the innermost trapping trench comprises the trapping trench sections 381.1 , 381.2, 381.3 and 381.4. It is also possible to form a circumferentially extending trapping trench 381 , 382 and 383 without an interruption, but in terms of production this may be more difficult than producing a trapping trench 381 , 382, 383 having a plurality of interruptions, and in particular sectionally linearly producing trapping trench sections: A trapping trench 381 , 382, 383 or a trapping trench section can be produced in a very simple manner by means of etching technology, for example. Isotropic or anisotropic etching methods can be used in this case.

A trapping trench system 381 , 382, 383 is suitable for reducing or stopping the migration or movement of disturbance particles 701 on the surface of the multi-aperture arrangement 350. This fundamentally makes use of the effect that during a migration of disturbance particles 701 through a trapping trench system 381 , 382, 383, potential energy and kinetic energy are repeatedly converted into one another, with a loss of energy taking place overall on account of friction effects. As a result, the mobility or movement of disturbance particles 701 is continuously reduced until it totally stops, where applicable. Moreover, a trapping trench system 381 , 382, 383 increases the area of the surface to/on which disturbance particles may adhere or have settled compared with a planar surface of the multi-aperture plate 304, which results in an increased interaction between the disturbance particles and the first multi-aperture plate or the trench surface, such that van der Waals forces between firstly disturbance particles and secondly the trench or the first multi-aperture plate 304 are increased, for which reason the momentum of disturbance particles is reduced further.

The number of trapping trenches 381 , 382, 383 of the trapping trench system can be chosen differently. In principle, providing a plurality of trapping trenches 381 , 382, 383 is better than providing a single trapping trench 381. Nevertheless, it is possible for just a single trapping trench 381 to be provided. Generally, it is advantageous if a sequence of trapping trenches 381 , 382, 383 is provided, wherein this sequence extends outwards away from the multi-aperture region 355. In this regard, the trapping trench 381 in Figure 18 forms the innermost trapping trench, the trapping trench 382 forms a second trapping trench arranged further outwards, and the trapping trench 383 forms the trapping trench arranged outermost in the example shown. Moreover, it is possible to provide even further trapping trenches, which are in turn arranged further outwards.

It is possible for a cross-sectional shape of trapping trenches 381 , 382 and 383 to be chosen to be identical or else to be chosen to be different for all the trapping trenches 381 , 382, 383. The choice of an identical cross-sectional shape is preferred since this can simplify the production of the trapping trench system having the trapping trenches 381 , 382, 383.

Besides the shape of the cross-section itself, however, the dimensions of the cross-sections can also either each be identical among different trapping trenches 381 , 382, 383 or they can be different. The following figures show a number of exemplary embodiments in respect thereof:

Figure 19 schematically shows trapping trenches 381 , 382, 383 and 384 in a sectional view. The illustration shows a sectional view beginning at the multi-aperture region 355 (left-hand side in Figure 19) away from the multi-aperture region 355 (right-hand side in Figure 19).

In Figure 19a, all four trapping trenches 381 , 382, 383 and 384 have the same cross-sectional shape; the cross-sectional shape is in each case that of a rectangle. However, the specific dimensions of the respective cross-sections of the trapping trenches 381 , 382, 383, 384 are different in each case in pairs: a depth t of the innermost trapping trench 381 is the largest, and the depth t then progressively decreases from the inner area outwards. However, the depth t could also progressively increase. In this embodiment variant of the invention, a width b of all the trapping trenches 381 , 382, 383, 384 remains constant, but it could also vary. A distance a between mutually adjacent trapping trenches 381 , 382, 383, 384 is not varied in this embodiment, but rather remains constant, but it could also vary.

In the example illustrated in Figure 19b, not just the shape of the respective cross-sections of all the trapping trenches 381 , 382, 383, 384 is identical in each case, namely always rectangular. A width b of the trapping trenches 381 , 382, 383, 384 is also always the same, but it could also vary. The same applies to a distance a between mutually adjacent trapping trenches 381 , 382, 383, 384, which is not varied from the inner area outwards. However, this could also be different. The exemplary embodiments of the invention illustrated in Figure 19 can be produced by means of anisotropic etching methods.

Figure 20 schematically shows a further exemplary embodiment of a plurality of trapping trenches 381 , 382, 383, 384 in a sectional view: The illustration once again shows a sectional view beginning near the multi-aperture region 355 (left-hand side in Figure 20), which then continues outwards (right-hand side in Figure 20). Unlike in the example in Figure 19, a cross- sectional shape of the trapping trenches 381 , 382, 383, 384 is substantially triangular. In the example in accordance with Figure 20a, the depth t of the trapping trenches 381 , 382, 383, 384 varies, while the depth t in the example in accordance with Figure 20b remains constant. In the example shown, the widths b of the trenches are also kept constant, as is the distance a between mutually adjacent trapping trenches 381 , 382, 383, 384. However, this could also be realized differently. These cross-sectional shapes and dimensions of trapping trenches 381 , 382, 383, 384 can likewise be produced by means of anisotropic etching methods.

Figure 21 schematically shows a further embodiment of trapping trenches 381 , 382, 383, 384 in a sectional view: in the example shown, the shape of a cross section of the trapping trenches 381 , 382, 383, 384 is round-shell-shaped or substantially corresponds to a circle segment. Such a shape of trapping trenches 381 , 382, 383, 384 can be generated by means of isotropic etching methods. In Figure 21a, not only the shape but also the dimensions of the trapping trenches 381 , 382, 383, 384 are identical, but they could also vary. In Figure 21b, by contrast, the shape of the cross-sections is identical, but the dimensions vary: Both a depth t and the maximum width b of the trapping trenches 381 , 382, 383, 384 decrease from left to right, that is to say from the multi-aperture region 355 outwards in the example shown. The distance a between mutually adjacent trenches at the opening side can vary or be kept constant.

Figure 22 schematically shows a first multi-aperture plate or filter plate 304 in a sectional view. In accordance with this embodiment, a central trench 387 is provided in the multi-aperture plate 304, wherein the entire multi-aperture region 355 is arranged in this central trench 387. The outer region 356 of the first multi-aperture plate 304 is not arranged in the central trench 387. Accordingly, the trapping trenches 381 , 382 arranged in the outer region 356 are not arranged in the central trench 387 either. In the exemplary embodiment shown, it is the case that a respective trench depth t of the sequence of trapping trenches 381 , 382 arranged in the outer region 356 increases from the inner area outwards. The innermost trench 381 has a depth t1 which is smaller than the depth t2 of the trapping trench 382 situated further outwards. In the example shown, furthermore, the depth of both trapping trenches 381 , 382 is less than that of the central trapping trench 387.

The specific sequence of the trapping trenches 381 , 382 or else of further trapping trenches (not illustrated in Figure 22) in combination with the central trapping trench 387 ensures a better stability of the first multi-aperture plate 304 overall.

In the case of many first multi-aperture plates 304 or filter plates 304, the central trench 387 arises on account of the production method for multi-aperture plates: this is because production employs MEMS techniques and planar integration techniques, which virtually automatically result in a central trench 387. The entire surface of the first multi-aperture plate 304 with the central trench 387 and the trench system with the trapping trenches 381 , 382 can be provided with a conductive layer, in particular a metallic layer. This ensures, in the event of this layer 99 being earthed, that particles, and in particular electrons, incident on the filter plate 304 during the formation of the first individual particle beams 3 can be absorbed and discharged there.

In accordance with one embodiment, the following relation holds true for a depth t of the central trench: 10 pm < t < 200 pm. However, it is also possible not to provide a central trench at all.

In accordance with one preferred embodiment, the following relation holds true for a trench depth t of a trapping trench 381 , 382, 383, 384: 10 pm < t < 180 pm. Additionally or alternatively, the following relation can hold true for a maximum trench width b of a trapping trench 381 , 382, 383, 384: 8 pm < b < 200 pm, in particular 8 pm < b < 20 pm or 8 pm < b < 18 pm. Additionally or alternatively, the following relation can hold true for a distance a between mutually adjacent trapping trenches 381 , 382, 383, 384: b/a > 1.5, preferably b/a > 2.0. However, it is also possible for the relation b/a to be significantly greater than 2.0; this depends in particular on the cross-sectional shape of the trench cross-sections. The distance a between mutually adjacent trapping trenches is measured here at the surface of the multi-aperture plate, and in particular of the filter plate 304. The maximum trench width b is measured at the widest point of the trapping trench, which can be present at an arbitrary position within the trapping trench 381 , 382, 383, 384 depending on the cross-sectional shape of the trapping trench 381 , 382, 383, 384. What is important, of course, is that mutually adjacent trapping trenches 381 , 382, 383, 384 are at a minimum distance from one another, thereby preventing an unwanted breach between mutually adjacent trapping trenches 381 , 382, 383, 384. In the embodiment variants shown in Figure 19 and Figure 21 , the following can hold true for such a minimum distance Ma, for example: 20 pm < Ma < 40 pm. In the embodiment variants shown in Figure 20, by contrast, the minimum distance Ma corresponds to the distance a and can be chosen to be as small as desired, in principle.

Figure 23 schematically shows a multi-aperture arrangement 350 of a multiple particle beam system 1 with a preceding pre-aperture 379 and a succeeding exit aperture 378. The preaperture 379 trims an expanded particle beam before the latter is incident on the multi-aperture arrangement 350. This pre-aperture 379 is formed in a stepped manner with exactly one step. The stepping can constitute an additional mechanical barrier for disturbance particles en route to the multi-aperture arrangement 350 which approach the multi-aperture arrangement 350 on the particle source side. In the example shown, an exit aperture 378 is additionally provided downstream of the multi-aperture arrangement 350, which exit aperture is formed in a stepped manner with exactly one step. This step can in turn constitute an additional mechanical barrier for disturbance particles en route to the multi-aperture arrangement 350 which approach the multi-aperture arrangement 350 on the object side.

The exemplary embodiments of the invention described with reference to the figures should be understood to be merely by way of example and non-limiting for the invention.

It is possible for the exemplary embodiments described to be combined with one another in full or in part, provided that no technical contradictions whatsoever arise as a result.

What is disclosed is a multiple particle beam system and a method for operating same in a decontamination mode, wherein charged disturbance particles situated in a sensitive region of a multi-aperture arrangement are trapped and removed from the sensitive region. Electrostatic trapping electrodes are arranged and controlled in a specific way and/or a trapping trench system is used for trapping the charged disturbance particles. The charged disturbance particles are stored during the normal operating mode of the multiple particle beam system in such a way that the charged disturbance particles do not disturb normal operation.

The invention might be furthermore described by the following Clauses:

Clause 1 : Method for operating a multiple particle beam system, comprising the following steps: providing a multiple particle beam system having a multi-aperture arrangement and having at least two trapping electrodes, wherein the multi-aperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multi-aperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system, wherein a first trapping electrode is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, wherein a second trapping electrode is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, and wherein the second trapping electrode is arranged further away from the particle-optical axis than the first trapping electrode; operating the multiple particle beam system in a decontamination mode, which involves trapping charged disturbance particles in a sensitive region of the multi-aperture arrangement, wherein the decontamination mode comprises the following steps (a) to (c) in the specified order:

(a) providing the same potential at the multi-aperture arrangement, at the first trapping electrode and at the second trapping electrode;

(b) changing the potential at the first trapping electrode and generating a first electrostatic trapping field between the first trapping electrode and the multi-aperture arrangement, such that charged disturbance particles can migrate from the multi-aperture arrangement to the first trapping electrode; and

(c) changing the potential at the second trapping electrode and generating a second electrostatic trapping field between the second trapping electrode and the first trapping electrode, wherein the second electrostatic trapping field is stronger than the first electrostatic trapping field, such that charged disturbance particles can migrate from the first trapping electrode to the second trapping electrode; and operating the multiple particle beam system in a normal operating mode, in which the multiplicity of charged individual particle beams pass through the multi-aperture arrangement, wherein in the normal operating mode the same potential is provided at the multi-aperture arrangement and at the first trapping electrode and wherein a different potential from that provided at the multi-aperture arrangement is provided at one of the other trapping electrodes, such that the charged disturbance particles remain at this trapping electrode, which constitutes a storage trapping electrode, in the normal operating mode.

Clause 2: Method according to Clause 1 , wherein more than two trapping electrodes are provided, and wherein a different potential from that provided at the multi-aperture arrangement is provided at exactly one of the trapping electrodes in the normal operating mode.

Clause 3: Method according to Clause 2, wherein the exactly one trapping electrode at which a different potential from that at the multi-aperture arrangement is provided is that one of the trapping electrodes which is situated furthest towards the outside relative to the particle-optical axis of the multiple particle beam system.

Clause 4: Method according to any of the preceding Clauses, wherein in the decontamination mode after step (c) the following step is furthermore carried out:

(d) changing the potential at the first trapping electrode, wherein the direction of the second electrostatic trapping field is not changed as a result.

Clause 5: Method according to Clause 4, wherein the potential at the first trapping electrode is reduced in terms of its absolute magnitude while maintaining its sign.

Clause 6: Method according to Clause 4, wherein the potential at the first trapping electrode is set to earth potential.

Clause 7: Method according to Clause 4, wherein the polarity of the potential at the first trapping electrode is reversed.

Clause 8: Method according to any of the preceding Clauses, wherein a third trapping electrode is provided, which is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, wherein the third trapping electrode is arranged further away from the particle-optical axis Z than the second trapping electrode, and wherein after step (c) and in particular after the optional step (d) in the decontamination mode the following step is furthermore carried out:

(e) changing the potential at the third trapping electrode and generating a third electrostatic trapping field between the third trapping electrode and the second trapping electrode, wherein the third electrostatic trapping field is stronger than the second electrostatic trapping field, such that charged disturbance particles can migrate from the second trapping electrode to the third trapping electrode.

Clause 9: Method according to the preceding Clause, wherein in the decontamination mode after step (e) the following step is furthermore carried out:

(f) changing the potential at the second trapping electrode, wherein the direction of the third electrostatic trapping field is not changed as a result.

Clause 10: Method according to any of the preceding Clauses, wherein in the normal operating mode the electrostatic field of the storage trapping electrode is shielded, such that it does not disturb the beam shaping.

Clause 11 : Method according to any of the preceding Clauses, wherein at least one of the trapping electrodes is not used for beam shaping in the normal operating mode of the multiple particle beam system.

Clause 12: Method according to any of the preceding Clauses, wherein at least one of the trapping electrodes is used as trapping electrode in the decontamination mode and for beam shaping in the normal operating mode of the multiple particle beam system.

Claus 13: Method according to any of the preceding Clauses, wherein a plurality of trapping electrodes arranged in a manner extending circumferentially around the particle-optical axis are provided both above and below the multiaperture arrangement relative to the particle-optical beam path, and wherein method steps (a) to (c) are carried out by means of the respective trapping electrodes both above the multi-aperture arrangement and below the multi-aperture arrangement.

Clause 14: Method according to any of the preceding Clauses, wherein in the decontamination mode a first extraction potential is provided at an upper multi-aperture plate of the multi-aperture arrangement and wherein a second extraction potential is provided at a lower multi-aperture plate of the multi-aperture arrangement, wherein the first extraction potential and the second extraction potential are different, such that charged disturbance particles can be extracted from the interior of the multi-aperture arrangement between the upper multi-aperture plate and the lower multi-aperture plate on account of the applied electrostatic field.

Clause 15: Method according to any of the preceding Clauses, wherein in the decontamination mode and in particular before step (a) the following step is furthermore carried out:

(g) irradiating the multi-aperture arrangement for the electrostatic charging of disturbance particles.

Clause 16: Method according to the preceding Clause, wherein the multi-aperture arrangement is irradiated both on the source side and on the object side in relation to the particle-optical beam path.

Clause 17: Method according to the preceding Clause, furthermore comprising the following step:

(h) inserting a beam stop into the particle-optical beam path below the multi-aperture arrangement, such that upon the beam stop being irradiated, through the multi-aperture arrangement, the irradiating charged particles are backscattered and thereby irradiate the multi-aperture arrangement on the object side.

Clause 18: Method according to any of the preceding Clauses, furthermore comprising the following step in the decontamination mode and in particular after steps (g) and (h):

(i) providing vibrations at the multi-aperture arrangement.

Clause 19: Method according to the preceding Clause, wherein the provided vibrations comprise mechanical vibrations.

Clause 20: Method according to any of Clauses 18 to 19, wherein the provided vibrations comprise sound oscillations and/or ultrasound oscillations.

Clause 21 : Method according to any of the preceding Clauses, furthermore comprising the following step in the decontamination mode and in particular after steps (g) and (h):

(j) providing an alternating electric field near the surface at the multi-aperture arrangement, wherein the direction of the electrostatic field is oriented parallel to one of the surfaces of the multi-aperture arrangement. Clause 22: Multiple particle beam system, in particular multi-beam particle microscope, comprising the following: a multi-beam generator having a multi-aperture arrangement, wherein the multiaperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multiaperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system, a first trapping electrode arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof; a second trapping electrode arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, a mode selection device in order to operate the multiple particle beam system in the normal operating mode or in a decontamination mode, wherein the decontamination mode involves trapping charged disturbance particles from a sensitive region of the multi-aperture arrangement comprising the multi-aperture region by means of the trapping electrodes; and a controller for controlling the multiple particle beam system; wherein the controller is configured to provide an adjustable potential at the first trapping electrode, to provide an adjustable potential at the second trapping electrode and to provide a potential, in particular earth potential, at the multi-aperture arrangement.

Clause 23: Multiple particle beam system according to Clause 22, furthermore comprising the following: an electrostatic shielding element arranged at a surface of the multi-aperture arrangement and in a manner projecting from this surface and extending circumferentially around the multi-aperture region of the multi-aperture arrangement; and wherein the second trapping electrode and the electrostatic shielding element are arranged at the same level relative to the particle-optical beam path, such that the electrostatic shielding element can shield an electrostatic field of the second shielding electrode in the normal operating mode, wherein the first trapping electrode is arranged above the second trapping electrode and above the electrostatic shielding element relative to the particle-optical beam path, and wherein the controller is configured to provide the same potential, and in particular earth potential, at the multi-aperture arrangement and at the electrostatic shielding element.

Clause 24: Multiple particle beam system according to Clause 23, wherein the first trapping electrode is arranged nearer to the particle-optical axis than the second trapping electrode; and/or wherein the first trapping electrode is arranged further away from the particle-optical axis than the electrostatic shielding element.

Clause 25: Multiple particle beam system according to either of Clauses 23 and 24, wherein the shielding element comprises a shielding ring, the profile of which is substantially triangular.

Clause 26: Multiple particle beam system according to any of Clauses 22 to 25, wherein the multi-beam generator is arranged in a multi-beam generator vacuum chamber, into which an evacuable beam tube leads on the particle source side, charged particles being guided in said beam tube.

Clause 27: Multiple particle beam system according to the preceding Clause, wherein the first trapping electrode and the second trapping electrode are arranged such that they are drawn back laterally behind an imaginary extension of the beam tube towards the multi-aperture arrangement.

Clause 28: Multiple particle beam system according to any of Clauses 22 to 27, comprising at least two further trapping electrodes which are arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multiaperture arrangement in the outer region thereof and which are arranged below the multiaperture arrangement relative to the particle-optical beam path, wherein the controller is configured to control the further trapping electrodes and to provide a respective individually adjustable potential at each of the trapping electrodes.

Clause 29: Multiple particle beam system according to any of Clauses 22 to 28, wherein a profile of one of the trapping electrodes is not circular and not elliptic.

Clause 30: Multiple particle beam system according to any of Clauses 22 to 29, furthermore comprising a flood gun for irradiating the multi-aperture arrangement, and wherein the controller is configured to control the flood gun in the decontamination mode for irradiation of the multi-aperture arrangement.

Clause 31: Multiple particle beam system according to any of Clauses 22 to 30, furthermore comprising a particle source for generating a charged particle beam, wherein the multiple particle beam system is configured to direct the charged particle beam as illuminating particle beam onto the multi-aperture arrangement, wherein the controller is configured to control the particle source, and wherein the particle source is operable in a normal operating mode and in a flooding mode, wherein in the flooding mode the particle source emits fewer charged particles and/or charged particles with lower energy than in the normal operating mode.

Clause 32: Multiple particle beam system according to any of Clauses 22 to 31 , furthermore comprising a UV source and/or an x-ray source for irradiating the multiaperture arrangement.

Clause 33: Multiple particle beam system according to any of Clauses 26 to 32, wherein the multiple particle beam system furthermore comprises a beam stop insertable into the particle-optical beam path in the lower region of the multi-beam generator vacuum chamber, wherein the beam stop is configured to backscatter charged particles incident on it, such that charged particles backscattered at the beam stop can irradiate the multi-aperture arrangement on the rear side.

Clause 34: Multiple particle beam system according to any of Clauses 22 to 33, wherein the multi-aperture arrangement is in the form of a tongue, wherein an oscillation generator is arranged at the multi-aperture arrangement, and wherein the controller is configured to control the oscillation generator in the decontamination mode.

Clause 35: Multiple particle beam system according to the preceding Clause, wherein the oscillation generator provides mechanical vibrations or sound oscillations.

Clause 36: Multiple particle beam system according to any of Clauses 22 to 35, wherein the multiple particle beam system furthermore comprises a field generating means for generating an alternating electric field, which is arranged near the surface with respect to the multi-aperture arrangement and which is configured to generate an alternating electric field oriented parallel to the surface of the multi-aperture arrangement in the decontamination mode.

Clause 37: Multiple particle beam system according to any of Clauses 26 to 36, furthermore comprising a pump system having at least one vacuum pump, said pump system being connected to the multi-beam generator vacuum chamber by means of a pump line system, wherein a particle trap for trapping charged disturbance particles is arranged within the pump line system.

Clause 38: Multiple particle beam system according to the preceding Clause, wherein the particle trap is arranged directly in front of the entrance to the multi-beam generator vacuum chamber; or wherein the particle trap is arranged directly after an exit of a vacuum pump or disturbance particle source.

Clause 39: Multiple particle beam system according to either of Clauses 37 and 38, wherein the particle trap comprises a capacitor and a flood gun for emitting charged particles, in particular electrons, wherein the capacitor and the flood gun are arranged such that they are successively traversed by a gas stream upon ventilation of the multi-beam generator vacuum chamber, wherein the flood gun, in the pump line system, is arranged upstream of the capacitor in the ventilation direction of a gas stream for ventilating the multi-beam generator, and wherein the controller is configured to control and activate the capacitor for providing an electric field and the flood gun for emitting charged particles during a ventilation process of the multi-beam generator vacuum chamber.

Clause 40: Multiple particle beam system according to the preceding Clause, wherein the controller is configured to limit a gas flow through the pump line system during a critical time interval of the ventilation process and/or venting process and to operate the particle trap during the critical time interval.

Clause 41 : Multiple particle beam system according to either of Clauses 37 and 38, wherein the particle trap comprises a first capacitor and a second capacitor, wherein the first capacitor and the second capacitor are arranged such that they are successively traversed by a gas stream upon ventilation of the multi-beam generator vacuum chamber, wherein the first capacitor, in the pump line system, is arranged upstream of the second capacitor in the ventilation direction of a gas stream for ventilating the multi-beam generator, and wherein the controller is configured to control the first capacitor for providing an alternating electric field and the second capacitor for providing a non-alternating electrostatic field.

Clause 42: Multiple particle beam system according to the preceding Clause, wherein the controller is configured to limit a gas flow through the pump line system during a critical time interval of the ventilation process and/or venting process and to activate the particle trap during the critical time interval.

Clause 43: Multiple particle beam system according to Clause 40 or 42, wherein the critical time interval corresponds to the time interval in which the pressure in the pump line system is greater than or equal to 1 mbar during ventilation.

Clause 44: Multiple particle beam system, in particular multi-beam particle microscope, comprising the following: a multi-beam generator having a multi-aperture arrangement, wherein the multiaperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multi-aperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system, wherein a first multi-aperture plate of the multi-aperture arrangement is provided, which is the first through which the multiplicity of charged particles pass, and wherein the first multi-aperture plate comprises in its outer region a trapping trench system having at least one trapping trench for trapping charged disturbance particles.

Clause 45: Multiple particle beam system according to Clause 44, wherein the first multi-aperture plate including the trapping trench system comprises a metallic layer for stopping and absorbing charged particles incident thereon.

Clause 46: Multiple particle beam system according to either of Clauses 44 and 45, wherein the at least one trapping trench is formed in a manner extending circumferentially around the multi-aperture region. Clause 47: Multiple particle beam system according to any of Clauses 44 to 46, wherein the circumferentially extending trapping trench comprises one or more interruptions.

Clause 48: Multiple particle beam system according to any of Clauses 44 to 47, wherein a trapping trench is formed linearly in sections.

Clause 49: Multiple particle beam system according to any of Clauses 44 to 48, wherein the shape of a cross section of a trapping trench is rectangular, triangular or round-shell-shaped and/or is producible by means of etching technology.

Clause 50: Multiple particle beam system according to any of Clauses 44 to 49, wherein the trapping trench system, in a direction away from the multi-aperture region, comprises a sequence of trapping trenches having at least a first inner trapping trench and a second trapping trench arranged further outwards.

Clause 51 : Multiple particle beam system according to Clause 50, wherein the first trapping trench comprises a first cross-section, and wherein the second trapping trench comprises a second cross-section, wherein the shape of the first cross-section and of the second cross-section is identical, and wherein the dimensions of the first cross-section and of the second cross-section are identical.

Clause 52: Multiple particle beam system according to Clause 50, wherein the first trapping trench comprises a first cross-section, and wherein the second trapping trench comprises a second cross-section, wherein the shape of the first cross-section and of the second cross-section is identical, and wherein the dimensions of the first cross-section and of the second cross-section are different.

Clause 53: Multiple particle beam system according to Clause 50 or 52, wherein the entire multi-aperture region of the first multi-aperture plate is arranged in a central trench, wherein the outer region of the first multi-aperture plate is not arranged in the central trench, and wherein a respective trench depth of the sequence of trapping trenches arranged in the outer region increases from the inner area outwards.

Clause 54: Multiple particle beam system according to any of Clauses 44 to 53, wherein the entire multi-aperture region of the first multi-aperture plate is arranged in a central trench, and wherein the following relation holds true for a depth t of the central trench: 10pm < t < 200 pm.

Clause 55: Multiple particle beam system according to any of Clauses 44 to 54, wherein the following relation holds true for a trench depth t of a trapping trench: 10pm < t < 200pm, in particular 10pm < t < 20pm or 10pm < t < 18pm, and/or wherein the following relation holds true for a maximum trench width b of a trapping trench: 8pm < b < 12pm, and/or wherein the following relation holds true for a distance a between mutually adjacent trapping trenches: b/a > 1.5, in particular b/a > 2.0.

Clause 56: Multiple particle beam system according to any of Clauses 44 to 55, wherein the multiple particle beam system comprises a particle source for generating a charged particle beam, and wherein the multiple particle beam system is configured to direct the charged particle beam as illuminating particle beam onto the multi-aperture arrangement, and wherein the multiple particle beam system is configured, in a normal operating mode, to illuminate the multi-aperture region of the first multi-aperture plate and substantially not to illuminate the outer region of the first multi-aperture plate.

Clauses 57: Multiple particle beam system according to any of Clauses 44 to 56, furthermore comprising the following: a pre-aperture arranged upstream of the multi-aperture arrangement relative to the particle-optical beam path such that it can trim an expanded particle beam before the latter is incident on the multi-aperture arrangement, wherein the pre-aperture is formed in a stepped manner; and/or an exit aperture arranged downstream of the multi-aperture arrangement relative to the particle-optical beam path, and formed in a stepped manner.

List of reference signs multiple particle beam system, multi-beam particle microscope primary particle beams, first individual particle beams beam spots, incidence locations object, sample, wafer secondary particle beams, second individual particle beams computer system, controller sample surface, wafer surface image point of a second individual particle beam multi-pole electrode ring electrode spacer ring electrode aperture spacer absorbing and conductive layer object plane objective lens field lens axis beam crossover detector system projection lens system projection lens multi-particle detector projection lens projection lens beam crossover aperture filter, contrast stop collective anti-deflection system beam generating apparatus particle source extractor collimation lens system, condenser lens system multi-aperture plate, filter plate multi-beam particle generator multi-aperture plate field lens, aperture plate, counterelectrode field lens particle beam multi-aperture plate illuminating particle beam particle beam (flooding mode) backscattered electrons backscattered electrons intermediate image plane beam foci holding region membrane region multi-aperture arrangement aperture multi-aperture plate, multi-aperture arrangement multi-deflector array multi-aperture region outer region trapping electrode trapping electrode trapping electrode trapping electrode trapping electrode shield beam tube shielding element, shielding ring exit aperture pre-aperture multi-beam generator vacuum chamber trapping trench trapping trench trapping trench trapping trench oscillation generator mount central trench displaceable beam stop pre-counterelectrode 399 electrode, earth potential

400 beam splitter, magnet arrangement

500 scan deflector

600 displacement stage or positioning device

701 disturbance particle

702 disturbance particle

703 disturbance particle

704 disturbance particle

900 pump line system

901 ion getter pump

902 turbo pump

903 disturbance particle source, chamber

904 ventilation valve

910 particle trap

911 capacitor

912 flood gun

913 capacitor (alternating electric field) x direction y direction z direction

Z particle-optical axis

EA alternating electric field

ED non-alternating electric field t trench depth b maximum trench width a distance between adjacent trenches at the opening side

E1 intermediate image plane

E2 object plane

Claims

Patent Claims

1. Multiple particle beam system, in particular multi-beam particle microscope, comprising the following: a multi-beam generator having a multi-aperture arrangement, wherein the multiaperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multi-aperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system, wherein a first multi-aperture plate of the multi-aperture arrangement is provided, which is the first through which the multiplicity of charged particles pass, and wherein the first multi-aperture plate comprises in its outer region a trapping trench system having at least one trapping trench for trapping charged disturbance particles.

2. Multiple particle beam system according to Claim 1 , wherein the first multi-aperture plate including the trapping trench system comprises a metallic layer for stopping and absorbing charged particles incident thereon.

3. Multiple particle beam system according to either of Claims 1 and 2, wherein the at least one trapping trench is formed in a manner extending circumferentially around the multi-aperture region.

4. Multiple particle beam system according to any of Claims 1 to 3, wherein the circumferentially extending trapping trench comprises one or more interruptions.

5. Multiple particle beam system according to any of Claims 1 to 4, wherein a trapping trench is formed linearly in sections.

6. Multiple particle beam system according to any of Claims 1 to 5, wherein the shape of a cross section of a trapping trench is rectangular, triangular or round-shell-shaped and/or is producible by means of etching technology.

7. Multiple particle beam system according to any of Claims 1 to 6, wherein the trapping trench system, in a direction away from the multi-aperture region, comprises a sequence of trapping trenches having at least a first inner trapping trench and a second trapping trench arranged further outwards.

8. Multiple particle beam system according to Claim 7, wherein the first trapping trench comprises a first cross-section, and wherein the second trapping trench comprises a second cross-section, wherein the shape of the first cross-section and of the second cross-section is identical, and wherein the dimensions of the first cross-section and of the second cross-section are identical.

9. Multiple particle beam system according to Claim 7, wherein the first trapping trench comprises a first cross-section, and wherein the second trapping trench comprises a second cross-section, wherein the shape of the first cross-section and of the second cross-section is identical, and wherein the dimensions of the first cross-section and of the second cross-section are different.

10. Multiple particle beam system according to Claim 7 or 9, wherein the entire multi-aperture region of the first multi-aperture plate is arranged in a central trench, wherein the outer region of the first multi-aperture plate is not arranged in the central trench, and wherein a respective trench depth of the sequence of trapping trenches arranged in the outer region increases from the inner area outwards.

11. Multiple particle beam system according to any of Claims 1 to 10, wherein the entire multi-aperture region of the first multi-aperture plate is arranged in a central trench, and wherein the following relation holds true for a depth t of the central trench: 10pm < t < 200 pm.

12. Multiple particle beam system according to any of Claims 1 to 11 , wherein the following relation holds true for a trench depth t of a trapping trench: 10pm < t < 200pm, in particular 10pm < t < 20pm or 10pm < t < 18pm, and/or wherein the following relation holds true for a maximum trench width b of a trapping trench: 8pm < b < 12pm, and/or wherein the following relation holds true for a distance a between mutually adjacent trapping trenches: b/a > 1.5, in particular b/a > 2.0.

13. Multiple particle beam system according to any of Claims 1 to 12, wherein the multiple particle beam system comprises a particle source for generating a charged particle beam, and wherein the multiple particle beam system is configured to direct the charged particle beam as illuminating particle beam onto the multi-aperture arrangement, and wherein the multiple particle beam system is configured, in a normal operating mode, to illuminate the multi-aperture region of the first multi-aperture plate and substantially not to illuminate the outer region of the first multi-aperture plate.

14. Multiple particle beam system according to any of Claims 1 to 13, furthermore comprising the following: a pre-aperture arranged upstream of the multi-aperture arrangement relative to the particle-optical beam path such that it can trim an expanded particle beam before the latter is incident on the multi-aperture arrangement, wherein the pre-aperture is formed in a stepped manner; and/or an exit aperture arranged downstream of the multi-aperture arrangement relative to the particle-optical beam path, and formed in a stepped manner.

15. Method for operating a multiple particle beam system, comprising the following steps: providing a multiple particle beam system having a multi-aperture arrangement and having at least two trapping electrodes, wherein the multi-aperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multi-aperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system, wherein a first trapping electrode is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, wherein a second trapping electrode is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, and wherein the second trapping electrode is arranged further away from the particle-optical axis than the first trapping electrode; operating the multiple particle beam system in a decontamination mode, which involves trapping charged disturbance particles in a sensitive region of the multi-aperture arrangement, wherein the decontamination mode comprises the following steps (a) to (c) in the specified order:

16. Method according to Claim 15, wherein more than two trapping electrodes are provided, and wherein a different potential from that provided at the multi-aperture arrangement is provided at exactly one of the trapping electrodes in the normal operating mode.

17. Method according to Claim 16, wherein the exactly one trapping electrode at which a different potential from that at the multi-aperture arrangement is provided is that one of the trapping electrodes which is situated furthest towards the outside relative to the particle-optical axis of the multiple particle beam system.

18. Method according to any of claims 15 to 17, wherein in the decontamination mode after step (c) the following step is furthermore carried out:

19. Method according to Claim 18, wherein the potential at the first trapping electrode is reduced in terms of its absolute magnitude while maintaining its sign.

20. Method according to Claim 18, wherein the potential at the first trapping electrode is set to earth potential.

21. Method according to Claim 18, wherein the polarity of the potential at the first trapping electrode is reversed.

22. Method according to any of claims 15 to 21 , wherein a third trapping electrode is provided, which is arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, wherein the third trapping electrode is arranged further away from the particle-optical axis Z than the second trapping electrode, and wherein after step (c) and in particular after the optional step (d) in the decontamination mode the following step is furthermore carried out:

23. Method according to claim 22, wherein in the decontamination mode after step (e) the following step is furthermore carried out:

24. Method according to any of claims 15 to 23, wherein in the normal operating mode the electrostatic field of the storage trapping electrode is shielded, such that it does not disturb the beam shaping.

25. Method according to any of claims 15 to 24, wherein at least one of the trapping electrodes is not used for beam shaping in the normal operating mode of the multiple particle beam system.

26. Method according to any of claims 15 to 25, wherein at least one of the trapping electrodes is used as trapping electrode in the decontamination mode and for beam shaping in the normal operating mode of the multiple particle beam system.

27. Method according to any of claims 15 to 26, wherein a plurality of trapping electrodes arranged in a manner extending circumferentially around the particle-optical axis are provided both above and below the multiaperture arrangement relative to the particle-optical beam path, and wherein method steps (a) to (c) are carried out by means of the respective trapping electrodes both above the multi-aperture arrangement and below the multi-aperture arrangement.

28. Method according to any of claims 15 to 27, wherein in the decontamination mode a first extraction potential is provided at an upper multi-aperture plate of the multi-aperture arrangement and wherein a second extraction potential is provided at a lower multi-aperture plate of the multi-aperture arrangement, wherein the first extraction potential and the second extraction potential are different, such that charged disturbance particles can be extracted from the interior of the multi-aperture arrangement between the upper multi-aperture plate and the lower multi-aperture plate on account of the applied electrostatic field.

29. Method according to any of claims 15 to 28, wherein in the decontamination mode and in particular before step (a) the following step is furthermore carried out:

30. Method according to claim 29, wherein the multi-aperture arrangement is irradiated both on the source side and on the object side in relation to the particle-optical beam path.

31 . Method according to claim 30, furthermore comprising the following step:

32. Method according to any of claims 15 to 31 , furthermore comprising the following step in the decontamination mode and in particular after steps (g) and (h):

(i) providing vibrations at the multi-aperture arrangement.

33. Method according to claim 32, wherein the provided vibrations comprise mechanical vibrations.

34. Method according to any of Claims 32 to 33, wherein the provided vibrations comprise sound oscillations and/or ultrasound oscillations.

35. Method according to any of claims 15 to 34, furthermore comprising the following step in the decontamination mode and in particular after steps (g) and (h):

(j) providing an alternating electric field near the surface at the multi-aperture arrangement, wherein the direction of the electrostatic field is oriented parallel to one of the surfaces of the multi-aperture arrangement.

36. Multiple particle beam system, in particular multi-beam particle microscope, comprising the following: a multi-beam generator having a multi-aperture arrangement, wherein the multiaperture arrangement comprises a plurality of multi-aperture plates, wherein each of the multiaperture plates comprises a multi-aperture region having a multiplicity of apertures and an outer region around the multi-aperture region, wherein a multiplicity of charged individual particle beams pass through the multiplicity of apertures in a normal operating mode of the multiple particle beam system, a first trapping electrode arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof; a second trapping electrode arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multi-aperture arrangement in the outer region thereof, a mode selection device in order to operate the multiple particle beam system in the normal operating mode or in a decontamination mode, wherein the decontamination mode involves trapping charged disturbance particles from a sensitive region of the multi-aperture arrangement comprising the multi-aperture region by means of the trapping electrodes; and a controller for controlling the multiple particle beam system; wherein the controller is configured to provide an adjustable potential at the first trapping electrode, to provide an adjustable potential at the second trapping electrode and to provide a potential, in particular earth potential, at the multi-aperture arrangement.

37. Multiple particle beam system according to Claim 36, furthermore comprising the following: an electrostatic shielding element arranged at a surface of the multi-aperture arrangement and in a manner projecting from this surface and extending circumferentially around the multi-aperture region of the multi-aperture arrangement; and wherein the second trapping electrode and the electrostatic shielding element are arranged at the same level relative to the particle-optical beam path, such that the electrostatic shielding element can shield an electrostatic field of the second shielding electrode in the normal operating mode, wherein the first trapping electrode is arranged above the second trapping electrode and above the electrostatic shielding element relative to the particle-optical beam path, and wherein the controller is configured to provide the same potential, and in particular earth potential, at the multi-aperture arrangement and at the electrostatic shielding element.

38. Multiple particle beam system according to Claim 37, wherein the first trapping electrode is arranged nearer to the particle-optical axis than the second trapping electrode; and/or wherein the first trapping electrode is arranged further away from the particle-optical axis than the electrostatic shielding element.

39. Multiple particle beam system according to either of Claims 37 and 38, wherein the shielding element comprises a shielding ring, the profile of which is substantially triangular.

40. Multiple particle beam system according to any of Claims 36 to 39, wherein the multi-beam generator is arranged in a multi-beam generator vacuum chamber, into which an evacuable beam tube leads on the particle source side, charged particles being guided in said beam tube.

41 . Multiple particle beam system according to claim 40, wherein the first trapping electrode and the second trapping electrode are arranged such that they are drawn back laterally behind an imaginary extension of the beam tube towards the multi-aperture arrangement.

42. Multiple particle beam system according to any of Claims 36 to 41 , comprising at least two further trapping electrodes which are arranged in a manner extending circumferentially around the particle-optical axis Z of the multiple particle beam system and in a manner projected along the direction of the particle-optical axis onto the multiaperture arrangement in the outer region thereof and which are arranged below the multiaperture arrangement relative to the particle-optical beam path, wherein the controller is configured to control the further trapping electrodes and to provide a respective individually adjustable potential at each of the trapping electrodes.

43. Multiple particle beam system according to any of Claims 36 to 42, wherein a profile of one of the trapping electrodes is not circular and not elliptic.

44. Multiple particle beam system according to any of Claims 36 to 43, furthermore comprising a flood gun for irradiating the multi-aperture arrangement, and wherein the controller is configured to control the flood gun in the decontamination mode for irradiation of the multi-aperture arrangement.

45. Multiple particle beam system according to any of Claims 36 to 44, furthermore comprising a particle source for generating a charged particle beam, wherein the multiple particle beam system is configured to direct the charged particle beam as illuminating particle beam onto the multi-aperture arrangement, wherein the controller is configured to control the particle source, and wherein the particle source is operable in a normal operating mode and in a flooding mode, wherein in the flooding mode the particle source emits fewer charged particles and/or charged particles with lower energy than in the normal operating mode.

46. Multiple particle beam system according to any of Claims 36 to 45, furthermore comprising a UV source and/or an x-ray source for irradiating the multiaperture arrangement.

47. Multiple particle beam system according to any of Claims 40 to 46, wherein the multiple particle beam system furthermore comprises a beam stop insertable into the particle-optical beam path in the lower region of the multi-beam generator vacuum chamber, wherein the beam stop is configured to backscatter charged particles incident on it, such that charged particles backscattered at the beam stop can irradiate the multi-aperture arrangement on the rear side.

48. Multiple particle beam system according to any of Claims 36 to 47, wherein the multi-aperture arrangement is in the form of a tongue, wherein an oscillation generator is arranged at the multi-aperture arrangement, and wherein the controller is configured to control the oscillation generator in the decontamination mode.

49. Multiple particle beam system according to claim 48, wherein the oscillation generator provides mechanical vibrations or sound oscillations.

50. Multiple particle beam system according to any of Claims 36 to 49, wherein the multiple particle beam system furthermore comprises a field generating means for generating an alternating electric field, which is arranged near the surface with respect to the multi-aperture arrangement and which is configured to generate an alternating electric field oriented parallel to the surface of the multi-aperture arrangement in the decontamination mode.

51. Multiple particle beam system according to any of Claims 40 to 50, furthermore comprising a pump system having at least one vacuum pump, said pump system being connected to the multi-beam generator vacuum chamber by means of a pump line system, wherein a particle trap for trapping charged disturbance particles is arranged within the pump line system.

52. Multiple particle beam system according to claim 51 , wherein the particle trap is arranged directly in front of the entrance to the multi-beam generator vacuum chamber; or wherein the particle trap is arranged directly after an exit of a vacuum pump or disturbance particle source.

53. Multiple particle beam system according to either of Claims 51 and 52, wherein the particle trap comprises a capacitor and a flood gun for emitting charged particles, in particular electrons, wherein the capacitor and the flood gun are arranged such that they are successively traversed by a gas stream upon ventilation of the multi-beam generator vacuum chamber, wherein the flood gun, in the pump line system, is arranged upstream of the capacitor in the ventilation direction of a gas stream for ventilating the multi-beam generator, and wherein the controller is configured to control and activate the capacitor for providing an electric field and the flood gun for emitting charged particles during a ventilation process of the multi-beam generator vacuum chamber.

54. Multiple particle beam system according to claim 53, wherein the controller is configured to limit a gas flow through the pump line system during a critical time interval of the ventilation process and/or venting process and to operate the particle trap during the critical time interval.

55. Multiple particle beam system according to either of Claims 51 and 52, wherein the particle trap comprises a first capacitor and a second capacitor, wherein the first capacitor and the second capacitor are arranged such that they are successively traversed by a gas stream upon ventilation of the multi-beam generator vacuum chamber, wherein the first capacitor, in the pump line system, is arranged upstream of the second capacitor in the ventilation direction of a gas stream for ventilating the multi-beam generator, and wherein the controller is configured to control the first capacitor for providing an alternating electric field and the second capacitor for providing a non-alternating electrostatic field.

56. Multiple particle beam system according to claim 55, wherein the controller is configured to limit a gas flow through the pump line system during a critical time interval of the ventilation process and/or venting process and to activate the particle trap during the critical time interval.

57. Multiple particle beam system according to Claim 54 or 56, wherein the critical time interval corresponds to the time interval in which the pressure in the pump line system is greater than or equal to 1 mbar during ventilation.