DE102024202078A1 - Methods for optimizing the acceptance of fluid- and structural-mechanically coupled systems - Google Patents

Abstract

The invention relates to methods for removing a device (10) for semiconductor lithography, wherein the device (10) has at least one fluid line system (39) filled with a fluid during operation and comprises the following method steps:
- Determination of mechanical vibrations of the device (10) when the fluid line (39) is filled with fluid
- Comparison of the determined mechanical vibrations with a specified specification
- Determination of mechanical vibrations of the device (10) in at least partially fluid-free fluid lines (39) in the event that the cause of an exceedance of the specification cannot be determined by the determined mechanical vibrations
- Determination of the cause of mechanical vibrations exceeding the specification based on the detected mechanical vibrations
- Elimination of the identified cause
- Repeat the previous process steps until the specification is reached.

Description

The invention relates to a method for optimizing the acceptance of fluid- and structural-mechanically coupled systems.

Projection exposure systems for semiconductor lithography are used to create extremely fine structures, particularly on semiconductor devices or other microstructured components. The operating principle of these systems is based on creating extremely fine structures down to the nanometer range by means of a generally reduced-size image of structures on a mask, using a so-called reticle, on an element to be structured, such as a wafer, which is provided with photosensitive material. The minimum dimensions of the created structures depend directly on the wavelength of the light used for imaging, the so-called useful light. The light sources used have emission wavelengths of 100 nm to 300 nm in a range known as the DUV range. Recently, light sources with an emission wavelength in the range of a few nanometers, for example between 1 nm and 120 nm, particularly in the range of 13.5 nm, have been increasingly used. This emission wavelength range is also referred to as the EUV range.

Such systems exhibit highly temperature-dependent behavior with regard to their imaging quality. Both structural elements not directly involved in optical imaging, such as mounts and holders or structures and frames, as well as optical elements themselves, such as lenses or, in the case of EUV lithography, mirrors, change their dimensions or surface shape when heated or cooled, which directly impacts the quality of the imaging produced by the system. The heating of the individual components of the system during operation is due, among other things, to the absorption of a portion of the useful radiation. To reduce this effect, both structural elements and optical elements are increasingly being tempered using a fluid, usually ultrapure water.

The supply lines for the fluid, referred to below as fluid lines, as well as the electrical and other supply lines, referred to below simply as lines, connect the comparatively strongly vibrating area of the projection exposure system with the area that is not or only minimally vibrating. Structurally, the two areas are decoupled from each other by multi-level active and passive decoupling systems, such as springs and dampers, so that no or only very little mechanical vibration is transferred from the strongly vibrating area to the minimally vibrating area. In the minimally vibrating area, for example, the lens for imaging the reticle structures onto the wafer is located. In the strongly vibrating area, for example, controls and electronics with fans or, in the case of temperature-controlled components, a fluid supply device with pumps for the fluid used for temperature control are located. The decoupling of the two areas is at least partially bridged by the supply lines, which is also referred to as a fluid or acoustic short circuit.

In addition to the transmission of mechanical vibrations via the supply lines themselves, i.e. the structural mechanics of the projection exposure system, mechanical vibrations are also transmitted via the slightly compressible fluid in the fluid lines. The mechanical vibrations are transmitted in the form of pressure fluctuations, which is why this transmission path is also referred to as water line acoustics (WLA). There are therefore two transmission paths for mechanical vibrations in the fluid lines, which are interdependent through the transmission of mechanical vibrations from one transmission path to the other and vice versa. Furthermore, a pipe filled with fluid behaves differently statically and, in particular, dynamically due to its mass alone, so that the two transmission paths are coupled with each other.

To decouple the lines and the structural-mechanical transmission path of the fluid lines, the lines or fluid lines are decoupled by decoupling elements, such as bellows and tuned mass dampers, which are arranged between the strongly vibrating and the minimally vibrating areas. The water line acoustics can be influenced using various measures, both passively in the form of devices or the design of the lines, and actively through control technology, to achieve a positive effect on image quality. For example, a gas volume connected to the fluid volume, such as a Helmholtz resonator, dampens the water line acoustics. The measures, manufacturing, and assembly technologies are sufficient to ensure the image quality of the projection exposure system.

For quality assurance, the projection exposure system or individual components are subjected to an acceptance test after assembly. This involves measuring mechanical vibrations or transfer functions from A to B, such as from a supporting structure via the decoupled supply lines to an optical element designed as a mirror, are determined and compared with specified specifications. In the case of a cooled component, the mechanical vibrations are determined using fluid-filled lines, so that both the transmission via the lines (i.e., the structural mechanics) and via the fluid (i.e., the water-line acoustics) are recorded.

This has the disadvantage that, due to the interactions between the two transmission paths and the coupling of the fluid-filled fluid lines described above, a clear cause for a mechanical vibration exceeding the specifications can only be found after a complex search, or even not at all. This leads to reintegration, i.e., to at least partial disassembly of the components or the projection exposure system, and thus to increased acceptance testing effort, which negatively impacts manufacturing costs.

The object of the present invention is to provide a method which eliminates the disadvantages of the prior art described above.

This object is achieved by a method having the features of independent claim 1. The subclaims relate to advantageous developments and variants of the invention.

• - Ermittlung von mechanischen Schwingungen der Vorrichtung bei mit Fluid gefüllten Fluidleitung.
• - Vergleich der ermittelten mechanischen Schwingungen mit einer festgelegten Spezifikation.
• - Ermittlung von mechanischen Schwingungen der Vorrichtung bei zumindest teilweise fluidfreien Fluidleitungen im Fall, dass die Ursache einer Überschreitung der Spezifikation durch die ermittelten mechanischen Schwingungen nicht ermittelt werden kann.
• - Ermittlung der Ursache der die Spezifikation überschreitenden mechanischen Schwingungen auf Basis der ermittelten mechanischen Schwingungen.
• - Behebung der Ursache.
• - Wiederholung der vorangehenden Verfahrensschritte, bis die Spezifikation erreicht ist.

A method according to the invention for removing a device for semiconductor lithography, wherein the device has at least one fluid line system filled with a fluid during operation, comprises the following method steps:

• - Determination of mechanical vibrations of the device when the fluid line is filled with fluid.
• - Comparison of the measured mechanical vibrations with a defined specification.
• - Determination of mechanical vibrations of the device in at least partially fluid-free fluid lines in the event that the cause of an exceedance of the specification cannot be determined by the determined mechanical vibrations.
• - Determination of the cause of mechanical vibrations exceeding the specification based on the detected mechanical vibrations.
• - Elimination of the cause.
• - Repeat the previous process steps until the specification is reached.

The method simplifies the determination of causes and thus enables faster acceptance of the system, which interacts via structural mechanics (i.e., lines and component connections) and acoustics (i.e., the fluid). This is particularly true when no clear cause can be determined when determining mechanical vibrations with fluid-filled fluid lines. Determining the mechanical vibrations in two different system states (fluid-filled and at least partially fluid-free) allows for a separation of the cause between structural mechanics and fluid, which is not possible in the interacting system. Furthermore, in the fluid-free system state, the coupling between fluid and mechanics is also eliminated.

Fluid systems often comprise multiple fluid circuits, so that, depending on the detected mechanical vibrations, the fluid system can initially be partially drained, for example, one fluid circuit at a time. This has the advantage of allowing the dominant acoustic transmission path to be identified, thus allowing the cause of the acoustics to be determined even more precisely.

In particular, the device can be designed as a component of a projection exposure system.

Furthermore, the device can be designed as the projection exposure system itself.

In a further embodiment, the mechanical vibrations can be determined with frequency resolution.

In particular, the mechanical vibrations can be determined locally, i.e., as mechanical vibrations detected at a specific location on the device, and/or as a transfer function between two points on the device. Local determination of the vibrations can be used to test a maximum permissible amplitude, such as the deflection of a connecting element to avoid collisions.

A transfer function between two points can be used to test a so-called system behavior. For example, in the case of a damped connecting element, the frequency-dependent damping behavior of the element, the damping factor, and/or the damped frequency can be checked. The term mechanical vibrations is used in the following. used as an umbrella term for both types of measurement and, where appropriate, referred to as local oscillations or transfer functions.

Furthermore, the determination of the cause may include a comparison of the mechanical vibrations determined by a measurement with a model.

In a first embodiment, the model can represent the fluid-filled device. This allows a comparison of the determined mechanical vibrations with an ideal model in a state comparable to the subsequent operating condition. The comparison with the model can provide initial clues to possible causes. The structure of the model corresponds to the real system, and the cause and effect, for example, in a transfer function, are known or can at least be limited to a specific range.

In particular, the model can represent the fluid-free device. This allows the measured mechanical vibrations to be compared with a model corresponding to the fluid-free device, which can advantageously simplify the process of identifying the cause. Especially if the cause could not be determined or could only be determined inadequately in a fluid-filled system, comparison with the model can provide further clues to the cause.

Furthermore, the model can represent the acoustic propagation in the device, i.e., be designed as an acoustic model. The model can be compared based on the difference between the mechanical vibrations determined in the two states of the device (fluid-filled and at least partially fluid-free).

In another embodiment, at least one model can be used to test a determined cause. Testing the solutions to eliminate the cause in the model, or possibly in two or three models, has two advantages.

On the one hand, it can be confirmed that the identified cause is also the actual cause. On the other hand, the effect of the solution on the device can be verified in advance using the models. In particular, it allows for a potentially necessary iterative approach to determining the solution, which has a positive effect on time expenditure and thus on manufacturing costs.

The use of at least one model, especially two or three models, can lead to the identification of all causes that have led to an exceedance of the specification and the determination of the measures necessary to resolve it with only one repetition of the procedure.

In a first embodiment, the measures to remedy the cause can include changing at least one stiffness of a connection and/or a component of the device. Mechanical connection stiffnesses can, for example, be changed relatively easily by retightening a screw connection. In the case of components such as decoupling elements, a change in stiffness may necessitate replacing the element. Furthermore, the components are also connected to one another via the fluid, thus exhibiting a connection stiffness. The connection stiffnesses can be adjusted, for example, by adjusting the pressure prevailing in the fluid lines.

Furthermore, measures to eliminate the cause may include changing at least one mass of a component of the device. The mass of components can, in principle, be achieved by adding or removing additional masses that are detachably connected to the component. Adjusting the mass can be particularly advantageous in cases where adjusting the stiffness is not possible or only possible with increased effort. This also applies in the opposite case.

In addition, measures to remedy the cause may include changing at least one damping effect of a connection and/or component of the device. This can be a solution, particularly in the case of resonators, such as Helmholtz resonators, which are used primarily in acoustics, i.e., for damping a fluid. Furthermore, the damping effect can also be adjusted by replacing a damper, such as a tuned mass damper.

In principle, the three basic parameters of an oscillating system, i.e. stiffness, mass and damping, can be adjusted as measures, whereby the accessibility and the cost of replacement are decisive in the choice of the measure.

The design of the device can be adapted based on the experience gained through the process. For example, options for attaching additional masses or simplified replacement of springs and/or dampers can be provided.

Alternatively, active components can be developed or, if available, used, which allow adjustment of stiffness, damping, and, if necessary, mass. Active modification of the acoustic mass is particularly conceivable in the field of acoustics.

In principle, all of the previously described changes and adjustments to stiffness, damping, and mass can be implemented as both active and passive measures. Furthermore, the aforementioned measures can be applied to both the structural and acoustic transmission paths.

• 1 schematisch im Meridionalschnitt eine Projektionsbelichtungsanlage für die EUV-Projektionslithografie,
• 2 schematisch im Meridionalschnitt eine Projektionsbelichtungsanlage für die DUV-Projektionslithografie,
• 3 eine aus dem Stand der Technik bekannte Projektionsbelichtungsanlage, und
• 4 ein Flussdiagramm zu einem erfindungsgemäßen Verfahren.

In the following, embodiments and variants of the invention are explained in more detail with reference to the drawings.

• 1 schematic meridional section of a projection exposure system for EUV projection lithography,
• 2 schematic meridional section of a projection exposure system for DUV projection lithography,
• 3 a projection exposure system known from the state of the art, and
• 4 a flowchart for a method according to the invention.

In the following, first with reference to the 1 The essential components of a projection exposure system 1 for microlithography are described by way of example. The description of the basic structure of the projection exposure system 1 and its components is not intended to be limiting.

One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

A reticle 7 arranged in the object field 5 is illuminated. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9.

In the 1 For explanation purposes, a Cartesian xyz coordinate system is shown. The x-direction is perpendicular to the plane of the drawing. The y-direction is horizontal and the z-direction is vertical. The scanning direction is in the 1 along the y-direction. The z-direction runs perpendicular to the object plane 6.

The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

Radiation source 3 is an EUV radiation source. Radiation source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation has, in particular, a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be a plasma source, for example, an LPP source (laser produced plasma) or a DPP source (gas discharged produced plasma). It can also be a synchrotron-based radiation source. Radiation source 3 can be a free-electron laser (FEL).

The illumination radiation 16 emanating from the radiation source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and/or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (GI), i.e., at angles of incidence greater than 45° relative to the normal direction of the mirror surface, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and/or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

After the collector 17, the illumination radiation 16 propagates through an intermediate kus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the radiation source 3 and the collector 17, and the illumination optics 4.

The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which are also referred to below as field facets. Of these facets 21, 1 only a few examples are shown.

The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

As for example from the DE 10 2008 009 600 A1 As is known, the first facets 21 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can in particular be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1 referred to.

Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction.

In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006/0132747 A1 , the EP 1 614 008 B1 and the US 6,573,978 .

The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

The second facets 23 can also be macroscopic facets, which can be round, rectangular or hexagonal, or alternatively facets composed of micromirrors. In this regard, reference is also made to the DE 10 2008 009 600 A1 referred to.

The second facets 23 may have planar or alternatively convex or concave curved reflection surfaces.

The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (fly's eye integrator).

It may be advantageous not to arrange the second facet mirror 22 exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the pupil facet mirror 22 may be arranged tilted relative to a pupil plane of the projection optics 10, as is shown, for example, in the DE 10 2017 220 586 A1 described.

With the help of the second facet mirror 22, the individual first facets 21 are imaged into the object field 5. The second facet mirror 22 is the last bundle-forming mirror or actually the last mirror for the illumination radiation 16 in the beam path before the object field 5.

In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (NI mirrors, normal incidence mirrors) and/or one or two mirrors for grazing incidence (GI mirrors, grazing incidence mirrors).

The illumination optics 4 has in the version shown in the 1 shown, after the collector 17 exactly three mirrors, namely the deflection mirror 19, the field facet mirror 20 and the pupil facet mirror 22.

In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1.

In the 1 In the example shown, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve, or a different number of mirrors M1 are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 are doubly obscured optics. The projection optics 10 have an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6, for example, 0.7 or 0.75.

Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

The projection optics 10 has a large object-image offset in the y-direction between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

The projection optics 10 can, in particular, be anamorphic. It has, in particular, different image scales βx, βy in the x and y directions. The two image scales βx, βy of the projection optics 10 are preferably (βx, βy) = (+/- 0.25, +/- 0.125). A positive image scale β means an image without image inversion. A negative sign for the image scale β means an image with image inversion.

The projection optics 10 thus leads to a reduction in the ratio 4:1 in the x-direction, i.e. in the direction perpendicular to the scanning direction.

The projection optics 10 results in a reduction of 8:1 in the y-direction, i.e. in the scanning direction.

Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions, for example, with absolute values of 0.125 or 0.25, are also possible.

The number of intermediate image planes in the x- and y-direction in the beam path between the object field 5 and the image field 11 can be the same or can be different, depending on the design of the projection optics 10. Examples of projection optics with different numbers of such intermediate images in the x- and y-direction are known from US 2018/0074303 A1 .

Each of the pupil facets 23 is assigned to exactly one of the field facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the field facets 21. The field facets 21 generate a plurality of images of the intermediate focus on the pupil facets 23 assigned to them.

The field facets 21 are each imaged onto the reticle 7 by an associated pupil facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object field 5 is, in particular, as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

By arranging the pupil facets, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the pupil facets that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting.

A likewise preferred pupil uniformity in the area of defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the pupil facet mirror 22. When the projection optics 10 images the center of the pupil facet mirror 22 telecentrically onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined spacing of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugate to it in spatial space. In particular, this surface exhibits a finite curvature.

It is possible that the projection optics 10 have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7. With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

At the 1 In the illustrated arrangement of the components of the illumination optics 4, the pupil facet mirror 22 is arranged in a surface conjugated to the entrance pupil of the projection optics 10. The field facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19.

The first facet mirror 20 is arranged tilted to an arrangement plane which is defined by the second facet mirror 22.

2 shows schematically in meridional section a further projection exposure system 101 for DUV projection lithography, in which the invention can also be used.

The structure of the projection exposure system 101 and the principle of imaging is comparable to that in 1 described structure and procedure. Identical components are provided with a 100% difference 1 raised reference symbols, the reference symbols in 2 So start with 101.

In contrast to a 1 Due to the longer wavelength of the DUV radiation 116 used as useful light in the range from 100 nm to 300 nm, in particular from 193 nm, in the EUV projection exposure system 101 described, refractive, diffractive and/or reflective optical elements 117, such as lenses, mirrors, prisms, cover plates and the like, can be used for imaging or illumination. The projection exposure system 101 essentially comprises an illumination system 102, a reticle holder 108 for receiving and precisely positioning a reticle 107 provided with a structure, by means of which the later structures on a wafer 113 are determined, a wafer holder 114 for holding, moving and precisely positioning this wafer 113 and a projection lens 110 with a plurality of optical elements 117 which are held via mounts 118 in a lens housing 119 of the projection lens 110.

The illumination system 102 provides DUV radiation 116 required for imaging the reticle 107 on the wafer 113. A laser, a plasma source, or the like can be used as the source for this radiation 116. The radiation 116 is shaped in the illumination system 102 via optical elements such that the DUV radiation 116 has the desired properties with regard to diameter, polarization, wavefront shape, and the like when it strikes the reticle 107.

The structure of the subsequent projection optics 101 with the lens housing 119 does not differ in principle from that in 1 described structure and is therefore not described further.

3 shows a roughly schematic representation of a projection optics 10 of a projection exposure apparatus 1 known from the prior art, as shown in the 1 The information in the 3 The projection optics 10 shown is arranged on the machine bed 30 of the projection exposure system 1 and comprises a base frame 31 which is designed to prevent the transmission of mechanical vibrations from the machine bed 30 is connected to the base frame 31 by a decoupling 49. For simplicity, all listed decouplings 49 without any specific significance for the invention are designated by the reference numeral 49 below, whereas relevant decouplings are each given a separate reference numeral.

The base frame 31 is connected via a further decoupling 49 to an intermediate frame 32, on which in turn a module frame 33 for receiving mirror modules 35 and a reference frame 34 are arranged via a decoupling 49. The decouplings 49 thus minimize the transmission of mechanical vibrations to the mirror modules 35.1, 35.2, 35.3, 35.4, 35.5, 35.6 arranged in the 3 not separately designated mirrors. The person skilled in the art will be aware that the decouplings 49 are not identical, but are each designed to meet the requirements placed on them. The mirror modules 35.1, 35.2, 35.3, 35.4, 35.5, 35.6 are connected to the module frame 33 via connections 36. The mirror modules 35.1, 35.2, 35.3, 35.4, 35.5, 35.6 further comprise sensors 38, which detect the position of the mirrors relative to the reference frame 34, whereby the position of the individual mirrors relative to one another and relative to other components of the projection exposure system 1, such as, for example, the 1 explained reticle 7 and the wafer 13 (both not shown) can be controlled via a control system not shown. The mirror modules 35.1, 35.2, 35.3, 35.4, 35.5, 35.6 are connected, for example, via a line 47 to a control system 46. The exemplary line 47 has a decoupling loop 44 between the base frame 31 and the intermediate frame 32, between the latter and the module frame 33, and between the latter and the mirror module 35.3, which decoupling loops serve to minimize the transmission of mechanical vibrations to the mirror modules 35.1, 35.2, 35.3, 35.4, 35.5, 35.6.

The mirror module 35.3 has, for example, fluid lines 39 for cooling the mirror with a fluid 40, such as pure water. The fluid 40 is guided from a first area 41.1 of a water cabinet 41 for providing and processing the fluid 40, which is connected to the base frame 31 and the machine bed 30 via decouplings 49, via a supply line 42 to the fluid line 39 of the mirror arranged on the mirror module 35.3 and is guided back via a discharge line 43 into a second area 41.2 of the water cabinet 41, wherein the two areas 41.1 and 41.2 are connected to one another via a connecting line 45. The supply line 42 and the discharge line 43 each have a decoupling loop 44 between the base frame 31 and the intermediate frame 32, between the intermediate frame 32 and the module frame 33, as well as between the intermediate frame 33 and the mirror (not shown). These decoupling loops also serve to minimize the transmission of mechanical vibrations to the mirror modules 35.1, 35.2, 35.3, 35.4, 35.5, and 35.6. The supply line 42 and the discharge line 43 further comprise both line dampers 50 for damping the mechanical vibrations transmitted via the lines 42, 43, and fluid dampers 60 for damping mechanical vibrations transmitted via the fluid 40. These are arranged at different locations on the lines 42, 43 due, among other things, to installation space restrictions, which can lead to an interaction of the mechanical vibrations transmitted via the lines 42, 43 and the fluid 40 even after the dampers.

After assembly, the projection optics 10 is accepted for quality control as an individual component of a projection exposure system 1, i.e., qualified. Among other things, the transmission of mechanical vibrations via the fluid lines 39, 42, 43 and the lines 47 is qualified for their effect on the mirrors.

• In einem ersten Verfahrensschritt 61 werden mechanische Schwingungen der Vorrichtung 10 bei mit Fluid gefüllter Fluidleitung 39 ermittelt.

4 describes a possible method for removing a device for semiconductor lithography, wherein the device has at least one fluid line filled with a fluid during operation, comprising the following method steps:

• In a first method step 61, mechanical vibrations of the device 10 are determined when the fluid line 39 is filled with fluid.

In a second method step 62, the determined mechanical vibrations are compared with a defined specification.

In a third method step 63, if the cause of exceeding the specification cannot be found by the determined mechanical vibrations, mechanical vibrations of the device 10 are determined with fluid lines that are at least partially free of fluid.

In a fourth method step 64, the cause of the mechanical vibrations exceeding the specification is determined on the basis of the detected mechanical vibrations.

In a fifth procedural step 65, the identified cause is remedied.

In a sixth process step 66, the preceding process steps are repeated until the specification is reached.

list of reference symbols

1

Projection exposure system

2

lighting system

3

Radiation source

4

Lighting optics

5

Object field

6

Object level

7

Reticle

8

Reticle holder

9

Reticle displacement drive

10

Projection optics

11

Image field

12

Image plane

13

wafer

14

Wafer holder

15

Wafer relocation drive

16

EUV radiation

17

collector

18

Intermediate focal plane

19

Deflecting mirror

20

Faceted mirror

21

facets

22

Faceted mirror

23

facets

30

machine bed

31

Base frame

32

intermediate frame

33

Module frame

34

Reference frame

35

Mirror module

36

Mirror connection

38

sensor

39

Fluid line

40

Fluid

41, 41.1, 41.2

Water Cabinet

42

supply line

43

derivative

44

Decoupling loop fluid line

45

Fluid reservoir connecting line

46

Control

47

Line

49

Decoupling in general

50

Line damper

101

Projection exposure system

102

lighting system

107

Reticle

108

Reticle holder

110

Projection optics

113

wafer

114

Wafer holder

116

DUV radiation

117

optical element

118

versions

119

lens housing

M1-M6

Mirror

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2008 009 600 A1 [0045, 0049]
• US 2006/0132747 A1 [0047]
• EP 1 614 008 B1 [0047]
• US 6,573,978 [0047]
• DE 10 2017 220 586 A1 [0052]
• US 2018/0074303 A1 [0066]

Claims (13)

A method for accepting a device (10) for semiconductor lithography, wherein the device (10) has at least one fluid line system (39) filled with a fluid during operation, comprising the following method steps: - Determining mechanical vibrations of the device (10) when the fluid line (39) is filled with fluid - Comparing the determined mechanical vibrations with a specified specification - Determining mechanical vibrations of the device (10) when the fluid lines (39) are at least partially free of fluid in the event that the cause of the specification being exceeded cannot be determined based on the determined mechanical vibrations - Determining the cause of the mechanical vibrations exceeding the specification based on the determined mechanical vibrations - Eliminating the determined cause - Repeating the preceding method steps until the specification is reached. Procedure according to Claim 1 , characterized in that the device (10) is designed as a component of a projection exposure system (1). Procedure according to Claim 1 , characterized in that the device (10) is designed as a projection exposure system (1). Method according to one of the preceding claims, characterized in that the mechanical vibrations are determined in a frequency-resolved manner. Method according to one of the preceding claims, characterized in that the mechanical vibrations are determined locally, i.e. as vibrations determined at a location of the device (10) and/or as a transfer function between two points of the device (10). Method according to one of the preceding claims, characterized in that the determination of the cause comprises a comparison of the mechanical vibrations determined by a measurement with a model. Procedure according to Claim 6 , characterized in that the model depicts the fluid-filled device (10). Method according to one of the Claims 6 or 7 , characterized in that the model depicts the fluid-free device (10). Method according to one of the Claims 6 until 8 , characterized in that the model represents the acoustic propagation of the fluid in the device (10). Method according to one of the preceding claims, characterized in that resonance frequencies in the device (10) are determined when determining the cause. Method according to one of the preceding claims, characterized in that the method comprises measures for eliminating the cause of a change in at least one stiffness of a connection and/or a component of the device (10). Method according to one of the preceding claims, characterized in that the method comprises measures for eliminating the cause of a change in at least one mass of a component of the device (10). Method according to one of the preceding claims, characterized in that the method comprises measures for eliminating the cause of a change in at least one damping effect of a connection (39, 47) and/or a component of the device (10).

Images