TWI492261B - Enhanced integrity projection lens assembly - Google Patents

Description

Projection lens assembly for improved integrity

The present invention relates to a projection lens assembly for directing a plurality of charged particle beamlets onto an image plane. The invention is particularly directed to a robust and compact projection lens assembly that allows for easy handling.

U.S. Patent No. 6,946,662 discloses a lens assembly for directing a plurality of charged particle beamlets onto an image plane. The lens assembly includes a plurality of electrodes having a beam passage region and a plurality of charged beam apertures formed therein. The electrodes are stacked along the optical path with insulating members separating the electrodes. The electrodes at the edges are clamped together to form a lens assembly. The image provided by the lens assembly is reduced and projected onto the wafer via a reduced electron optical system. The lens assembly is used to correct beam aberrations that will later occur in the projection path as the beam is zoomed out.

One disadvantage of the system disclosed in U.S. Patent No. 6,946,662 is that the lens assembly must be complex to provide the desired correction.

No. 7,091,504 to the applicant of the present application discloses an electron beam exposure apparatus comprising a focused electron optical system comprising an electrostatic lens array, wherein each lens directly focuses a corresponding individual beamlet having a cross section of less than 300 nm to the wafer on. Since this system does not require the reduction of the electro-optical system, it can be prevented from being caused by the beam aberration effect of the reduced electron optical system.

One disadvantage of the system disclosed in U.S. Patent No. 7,091,504 is that such an electro-optical system must be configured to be closer to the target.

Furthermore, in order to provide a stable electrostatic field in the downstream direction, the electrode substrates of the prior art as disclosed in, for example, U.S. Patent No. 6,946,662 are thin and configured to be close to each other, i.e., using insulating members on the sides of the electrodes. Separated by small distances. Such thin electrodes form the weakest part of the projection lens assembly; the electrodes may be susceptible to chipping or deformation during handling, and when sparks occur due to high potential differences between the electrodes, which are typically too severely damaged Cannot be used further. The replacement of the electrodes will result in significant downtime for the lithography equipment used.

It is an object of the present invention to provide a robust, compact modular projection lens assembly for projecting, for example, tens of thousands of beamlets or more of a plurality of charged particle beamlets onto a target. Another object of the present invention is to provide a modular projection lens assembly that can be easily manipulated and serviced and that can be placed as a unit.

Another object of the present invention is to provide a compact modular projection lens assembly that is easy to assemble in precise specifications, and a method for assembling such a projection lens assembly.

To this end, according to a first aspect, the present invention provides a projection lens assembly for guiding a plurality of charged particle beamlets onto an image plane, the projection lens assembly comprising small plurality of charged particles a first electrode and a second electrode of the bundle of one or more charged particles, and a housing, the housing comprising a through opening for allowing the plurality of charged particles to pass through, the first and second electrodes each comprising An array of lens apertures aligned with the through opening to allow passage of the one or more charged particles of the plurality of charged particle beamlets, wherein the outer casing includes a surrounding wall portion and has upstream and downstream end edges, and the projection lens The assembly further includes: at least one support member including a through opening for allowing the plurality of charged particles to pass through, wherein the at least one support member is attached to the outer casing, and wherein the first electrode and the second electrode are Supported by the at least one support member, wherein the first and second electrodes are disposed in or near a plane defined by a downstream end edge of the outer casing Plane. During manipulation of the projection lens assembly, the electrodes are protected by the surrounding wall of the outer casing. Moreover, since the electrodes are located downstream of the casing, a projection lens for the charged particle beamlets can be placed close to the target.

In one embodiment, the first electrode and the second electrode are attached to the support member by an adhesive connection. Since no fixture or screw that protrudes further is used further downstream of the second electrode, the second electrode can thus be placed in close proximity to the target, i.e., the distance is in the range of 50 to 100 microns. Moreover, during the construction of the projection lens assembly, the distance between the electrodes can be easily adjusted by using more or less adhesive when the adhesive is attached and then curing the adhesive.

In one embodiment, the support member is constructed of a non-conductive material. The support element can thus be used as an electrical insulator.

In one embodiment, the projection lens assembly includes one or both of the downstream and upstream end edges of the one or more support members of the one or more support members. In a preferred embodiment, the projection lens assembly includes a support member at a downstream end edge of the outer casing and another support member at an upstream end edge of the outer casing.

In one embodiment, the second electrode forms the end of the projection lens assembly in the downstream direction. Therefore, the second electrode can be placed very close to the target, reaching within 50 microns.

In one embodiment, the first and second electrodes are respectively disposed on the upstream surface and the downstream surface of the support member, the first electrode is spaced apart from the peripheral wall portion, and the support member is bridged between the first electrode and the periphery The distance between the walls. Since the most downstream electrode of the projection lens assembly is also the downstream end of the projection lens assembly, the distance between the most downstream electrode of the projection lens assembly and the patterned target can be minimized. Furthermore, in addition to the support electrode, the support element is also adapted to disperse the force exerted on the electrode and prevent its deformation. Preferably, the support member comprises a primary layer of insulating material such as borosilicate glass which can be easily machined to precise specifications and tolerances. Since the electrodes are thus robustly mounted in the projection lens assembly and protected to some extent from shock and other impact forces, the present invention provides a robust module that is relatively easy to replace and is a one-piece.

In one embodiment, the upstream surface of the support member is at least partially covered by a first conductive coating that is connected to the first electrode. The lead can be easily attached anywhere on the first coating to provide the first electrode with a potential for focusing a small beam of charged particles. Alternatively, the leads can be directly connected to the first electrode.

In one embodiment, the downstream surface of the support member is substantially covered by a second conductive coating that is connected to the second electrode. The two coatings have a dual function. First, the coatings act as conductors to establish a potential difference between the electrodes; second, the coatings substantially shield the downstream end of the lens assembly from external electromagnetic radiation and can thus form a Faraday cage ( Part of the Faraday cage).

In one embodiment, the projection lens assembly further includes a third electrode disposed upstream of the first electrode. Preferably, the third electrode and the second electrode are maintained at a fixed potential, and the potential of the first electrode is calibrated to fix the focus intensity for each of the projection lens assemblies to a specified level. Thus, a lens array is formed for the small beam of adjustable focus charged particles for which adjustment in focus does not substantially affect the electric field outside the volume spanned by the third and second electrodes.

In one embodiment, the second coating is an outer peripheral region extending radially from the through opening on the downstream surface of the support member to the upstream surface of the support member over the outer edge of the support member, and the first coating is from A through opening on the upstream surface of the support member extends radially outward. Preferably, the second coating is a fully facing downstream facing surface and an outer edge of the support member. A conductive lead for the first electrode can be attached anywhere on the first coating to which it is electrically connected. This facilitates placement of the leads for the electrodes.

In one embodiment, the surface facing the downstream of the support element and/or the surface facing the upstream is reinforced with a radially extending strip of adhesive. The support capacity of the support element can therefore be increased, even after its manufacture.

In one embodiment, the surrounding wall portion is electrically conductive and is connected to the second coating layer. The surrounding wall portion and the second coating thus provide substantial electromagnetic shielding for the charged particle beamlets across the projection lens assembly. Moreover, the support member of this structure can be adhered to the downstream end edge of the peripheral wall portion using a conductive adhesive without any additional lead wires being attached to the second coating layer or the second electrode.

In one embodiment, the support member further includes a dielectric collapse protection structure at or near the perimeter of the through opening. Preferably, the through opening of the support member has a stepped diameter that is smaller near the upstream surface of the support member and larger at the downstream surface near the support member. In addition, a dielectric collapse protection structure may be provided on or in the outer periphery of the first and/or second coating. Such a protective structure prevents sparking between the first and second electrodes, allowing a higher voltage to be applied between the first and second electrodes and thus a more uniform electric field to focus the charged particle beamlets.

In one embodiment, the non-conductive material of the support member, preferably comprised of borosilicate glass, separates the first and second electrodes by a distance of about 200 microns or less.

In one embodiment, the support element and the first electrode and/or the second electrode are substantially planar.

In one embodiment, the at least one support element comprises a first support element, a second support element and a cover element each having a through opening for the plurality of charged particle beamlets, wherein the cover element is disposed on the surrounding wall An upstream end edge of the portion, the second support member interconnects the cover member with the first electrode or the first support member. During manufacture of the lens assembly, once the surrounding wall portion and the support member have been attached to each other, a cover member can be used to substantially block the upstream side of the outer casing. Any space between the second support element and the cover element can be filled with an adhesive. This design allows for some relaxation of the tolerances and improves the structural integrity of the entire projection lens assembly.

In one embodiment, the second support element is provided with a deflector unit for providing deflection of the plurality of beamlets in the scanning direction. Advantageously, the deflector unit and the focus lens electrode need only be aligned during construction of the projection lens assembly without having to be aligned during insertion of the projection lens assembly into the lithography system, thus shortening the inspection or replacement of the projection lens assembly Microfilm system downtime.

In one embodiment, the cover element comprises a non-conductive material on the upstream facing surface of the cover element and a peripheral wall portion adjacent the outer casing. The electrically conductive upstream surface can be electrically connected to the deflector unit. The covering element can thus provide some shielding from external electromagnetic radiation and is electrically isolated from the surrounding wall.

In one embodiment, the projection lens assembly further includes a beam stop array for at least partially blocking the charged particle beamlets that have been deflected by the beam suppressor array to reach the target. When the beam stop array is disposed upstream of the deflector unit, the pivot point of the charged particle beamlets for which it is scanned can be configured to be substantially close to the image plane of the lens formed by the at least two electrodes. Alternatively, a beam stop array can be disposed between the lens and the deflector unit. The pivot point for the beamlet whose scan is moving can then be configured in substantially the same plane as the beam stop array.

In one embodiment, the deflector unit is adapted to deflect a plurality of beamlets near their associated pivot points with associated pivot points located in substantially the same plane as the beam stop array. As a result, any scanning deflection of the charged particle beamlets of the deflector unit does not substantially change the position of the beam spot on the beam stop array. The apertures in the beam stop array can thus be kept small, in particular smaller than the diameter of a single beamlet. Clearly, for example, via a beam suppressor placed upstream of the deflector unit, any non-scanning deflection of the beamlet will cause the beam spot on the beam stop array to move away from its associated aperture to prevent the beam from traveling The array is stopped by the beam.

In one embodiment, the at least one support element comprises a cover element having a through opening for allowing passage of the plurality of charged particles, wherein the outer casing comprises an upstream open end defined by an upstream edge, wherein the cover element is Suitable for substantially covering an upstream open end of the outer casing, wherein the first and second electrodes are included in the beam optics, and wherein the beam optic is an adhesive applied by the surface thereof facing the downstream surface of the cover member The body is supported by the covering element. In this embodiment, the downstream portion of the beam optics may be substantially freely depending. Thus, when the beam optic is substantially vertical, as is typical in a charged particle beam lithography system, there is no need to further support the weight of the beam optic at a downstream portion of the surrounding wall of the outer casing. It is not necessary to consider the distance between the downstream support element and the downstream end edge of the outer casing. By varying the distance between the cover element and the beam optics, the height of the projection lens assembly can be adjusted during construction.

In one embodiment, at least during the construction of the lens assembly, the cover member is provided with an additional through opening for applying an adhesive from an upstream position of the cover member to a surface facing the cover member downstream. Furthermore, once the cover element has been placed on the surrounding wall, such through openings can be used in turn to reach the interior of the projection lens assembly. For example, it is possible to glue the cover element to the beam optics via such through openings. In addition to facilitating the construction of the projection lens assembly, when the gas is evacuated from the interior of the projection lens assembly, the additional through opening also shortens the path that gas molecules must travel.

In one embodiment, the height of the adhesive body in the downstream direction is such that the covering member is spaced apart from the second electrode by a predetermined distance, preferably in the range of 2 mm to 2 cm.

In one embodiment, the second electrode forms the end of the beam optic in the downstream direction.

In one embodiment, the second electrode forms the end of the projection lens assembly in the downstream direction. It is therefore possible to place the target exposed to the charged particle beamlets very close to the second electrode to provide a sharp focus of the beamlets.

In one embodiment, the projection lens assembly further includes one or more positioning elements that are fixedly attached to the beam optics and the surrounding wall in an orientation substantially perpendicular to the direction of the through opening, and the beam optics are adapted for use Positioned at a substantial fixed distance from the surrounding wall. While such positioning elements are generally not suitable for supporting the entire weight of the beam optics when the projection lens assembly is in a substantially vertical position for use, the horizontal alignment and/or fixation of the beam optics is by such positioning elements. A lens lens assembly that is suitably implemented to provide a more robust and more accurate alignment.

In one embodiment, the surrounding wall portion comprises a conductive material that provides improved electromagnetic shielding inside the projection lens assembly.

In one embodiment, at least one of the positioning elements is electrically conductive and electrically connects the second electrode to the surrounding wall. The outer casing and the second electrode can thus be maintained at the same potential without the use of additional wiring. Preferably, the electrically conductive locating element is attached to the beam optics and the surrounding wall portion using a conductive adhesive.

In an alternate embodiment, the positioning element electrically connects another portion of the beam optic (eg, the other electrode) to the surrounding wall.

In one embodiment, the cover element comprises a non-conductive material of a conductive surface on a surface facing the upstream of the cover element and a peripheral wall portion adjacent the outer casing. The cover element can thus provide some shielding from external electromagnetic radiation and is electrically isolated from the surrounding wall.

In one embodiment, the surface facing the downstream of the cover member comprises a conductive surface on which the conductive surfaces on the upstream and downstream surfaces of the cover member are connected along one or more through openings in the cover member And extended. The electrically conductive surfaces further improve electromagnetic shielding and reduce static buildup on the cover element.

In one embodiment, the adhesive body is a conductive adhesive body that electrically connects the beam optics to a conductive surface on a surface that faces downstream of the cover member. The conductive surfaces facing the upstream and downstream cover elements can thus be electrically conductively coupled to at least a portion of the beam optics without the need for additional wiring for attachment therebetween.

In one embodiment, the cover element further comprises one or more encapsulation rings comprising an electrically insulating material and disposed on a boundary between the electrically conductive surface of the cover element and the non-conductive material. These encapsulating rings substantially reduce the chance of sparks occurring within the projection lens assembly.

In one embodiment, the beam optics further includes a deflector unit disposed upstream of the first electrode and adapted to provide scan deflection of the plurality of beamlets. Preferably, the deflector unit includes an electrically conductive outer surface that is electrically conductively coupled to the electrically conductive surface of the cover member to provide a high degree of electromagnetic shielding for the beamlets passing through the beam optics.

In one embodiment, the beam optics further includes a beam stop array disposed between the deflector unit and the second electrode. By placing the beam stop array relatively close to the second electrode, the dispersion of the beamlets before they pass through the second electrode is reduced, i.e., the beamlet profile remains clearly defined.

In one embodiment, the projection lens assembly further includes a conductive spacer that abuts and electrically connects the beam stop array to the first electrode. In this embodiment, the first electrode is at the same potential as the beam stop array. The voltage caused by charged particles incident on the array of stop beams or by the stop of the beam may be measured by measuring the potential of the first electrode. Moreover, in this embodiment, since the beam stop array is at the same potential as the first electrode, acceleration of the charged particles between the beam stop array and the first electrode can be avoided.

In one embodiment, the deflector unit is adapted to provide a scan deflection of a plurality of beamlets near their associated pivot points, the pivot points being in substantially the same plane as the beam stops the array. In this embodiment, any scanning deflection of the charged particle beamlets does not substantially change the position of the beam spot on the beam stop array. The apertures in the beam stop array can thus remain small, in particular less than the diameter of a single beamlet. It will be apparent that any non-scanning deflection of the beamlet, for example by a beam suppressor placed upstream of the deflector unit, moves the beam spot on the suppressor array to a position away from its associated aperture, preventing this small The beam travels through the beam to stop the array.

In one embodiment, the projection lens assembly includes a beam stop array disposed upstream of the deflector unit, and the deflector unit is adapted to deflect a plurality of beamlets near an associated pivot point, the pivot point being substantially a plane between the first and second electrodes. The beamlets may thus have their pivot point very close to the target plane and remain focused regardless of scanning deflection.

In one embodiment, an adhesive body is applied between the cover element and the next downstream structure to form a substantial annular connection therebetween. In the preferred embodiment, the connection is airtight.

In one embodiment, the assembly is adapted to be placed and/or replaced in a lithography system as a single unit.

According to a second aspect, the present invention provides a charged particle beam lithography system for directing a plurality of charged particle beamlets onto a target, the system comprising a projection lens assembly as described herein. In particular, such systems include: a beam source disposed upstream of the projection lens assembly to provide a plurality of charged particle beamlets; and a beam suppressor for providing extinguishing of the selected beamlets of the plurality of beamlets deflection. More particularly, such systems are suitable for operation in a vacuum environment. During the sizing of the target, the target and the surrounding wall are preferably maintained at the same potential, for example by electrically connecting the two to ground.

According to a third aspect, the present invention provides a method for assembling a projection lens assembly for directing a plurality of charged particle beamlets onto an image plane, the projection lens assembly comprising: a housing comprising a peripheral wall portion having upstream and downstream end edges; beam optics comprising first and second electrodes for focusing a plurality of charged particles of the plurality of charged particle beamlets; and a covering element; The housing and cover member includes a through opening for allowing the plurality of charged particles to pass through, and the first and second electrodes each comprise an array of lens apertures for allowing one or more of the plurality of charged particle beamlets Passing a small beam of charged particles; wherein the covering element is adapted to substantially cover an upstream edge of the outer casing; wherein the method comprises the steps of: aligning the beam optic with the through opening of the covering element to cause the plurality of charged particles to be beamlets Passing through, and causing the beam optics and the cover member to be separated by a gap; fixing the cover member to the outer casing to enable the cover An upstream element overlapping edge of the housing; is filled with the adhesive in a gap between the beam and the optic cover element to the support beam optics substantial adhesive to the cover member; make the adhesive is cured.

This method of assembling the projection lens assembly allows the overall height of the lens assembly to be easily adjusted without maintaining a plurality of spacers having different heights at hand. Moreover, since it can also include a deflector unit to provide a small beam of scanning deflection, the beam optics are substantially supported to the cover member, simplifying the construction and maintenance of the assembly; only the beam optics to the cover member The distance must be aligned, and since the projection lens assembly can be substantially opened on the downstream side, the components within the housing are easily accessible. Finally, a lighter and tighter projection lens assembly can be fabricated since no additional support elements are needed to support the beam optics on the downstream side.

In one embodiment, the method includes the additional step of adjusting the distance between the beam optic and the cover member when the adhesive has not yet cured. This distance can therefore be adjusted very accurately over a much shorter period of time when using pre-formed solid spacers. When the cover element and beam optics are spaced apart during construction of the projection lens assembly, the height of the adhesive body will increase and its width will decrease, and more adhesive can be applied to compensate for this reduction. Similarly, when the beam optics and the cover element are brought closer together, the height of the adhesive body will decrease and its width will increase. In this case, some of the adhesive can be removed. Conversely, when an adhesive that is only a sheet is used, such adjustment is not possible because such a sheet will be pulled apart when the cover member and the beam optics are moved away from each other. Preferably, an adhesive is used which, when cured, has a coefficient of thermal expansion similar to that of its abutting surface. The orientation of the cover element relative to the beam optics thus remains substantially fixed, even when the projection lens assembly is hot or cold. When the adhesive is an extremely low shrinkage adhesive, the strain on its abutment surface during the curing process is minimized.

In one embodiment, the distance between the beam optic and the cover element is adjusted such that the distance between the second electrode and the cover element is equal to a predetermined distance. Thus, even when individual beam optics may change to some extent, a substantially equal height projection lens assembly can be produced.

In one embodiment, the method includes the step of adjusting the distance: directing the plurality of beamlets toward the transmitted beam optics toward the beamlet profile sensor disposed at the target plane, the beamlet profile sensor Suitable for measuring a corresponding plurality of beamlet profiles; and changing the distance until the optimal measurement focus for the plurality of beamlets has been reached. As long as the adhesive is not yet cured, the focus and other properties of the projection lens assembly can be measured and at least partially adjusted by slightly changing the position of the beam optic relative to the cover member. Preferably, the beamlet intensity during this step is less than the beamlet intensity that would typically be used during the target exposure.

In one embodiment, at least during assembly, the cover member includes an additional through opening disposed about the through opening, and the step of filling the gap between the beam optic and the cover member includes transmitting through the additional through openings The adhesive is injected. The adhesive body can thus be easily formed by applying an adhesive to the covering member from various angles, since the inner side of the adhesive body can reach a through opening through which a plurality of small bundles are allowed to pass, and the adhesive body The outer side can be passed through an additional through opening. Conversely, a through opening can also be used to remove excess adhesive as long as it has not yet cured. After the adhesive body has been formed, the additional through openings can be closed, for example, the additional through openings are also filled with an adhesive. Alternatively, the additional through opening can be used to draw a vacuum within the projection lens assembly when it is open, or to circulate cleaning gas or plasma through the projection lens assembly.

In one embodiment, the projection lens assembly further includes a positioning element adapted to position the beam optics at a predetermined distance from the surrounding wall portion, and the method further comprises the step of attaching the positioning elements to the beam optics The device and the surrounding wall. These positioning elements help to separate the beam optics from the surrounding wall by a desired distance during the curing of the composition and the adhesive. Moreover, once the projection lens assembly has been constructed, the positioning elements prevent a similar pendulum motion of the downstream end of the beam optics.

According to a fourth aspect, the present invention provides a projection lens assembly for directing a plurality of charged particle beamlets onto an image plane, the projection lens assembly including a peripheral wall portion and upstream and downstream end edges a first electrode and a second electrode for focusing the one or more of the plurality of charged particle beamlets, and a support member comprising the same, the housing and the support member being included for allowing the plurality of charges a through opening through which the particle beamlets pass, and the first and second electrodes each comprise an array of lens apertures aligned with the through opening to allow passage of one or more charged particles from the plurality of charged particle beamlets, wherein The support member is attached to a downstream end edge of the outer casing, the second electrode forms an end of the projection lens assembly in a downstream direction, and the first electrode is spaced apart from the peripheral wall portion, the support member is bridged at the first electrode The distance between the surrounding walls.

In one embodiment, the first electrode and the second electrode are supported by the support member and are configured to be at or near the support member. Therefore, both electrodes can be disposed downstream of the support member.

In a preferred embodiment, the first and second electrodes are disposed on the upstream and downstream surfaces of the support member, respectively. Therefore, the first electrode is protected from damage by the outer casing and the support member.

Whenever possible, the various aspects and features described and illustrated in this specification can be applied individually. The aspects and features described in these individual aspects and in particular in the accompanying claims are hereby incorporated by reference.

Optical column 1 as is known in the prior art is shown in Figure 1A. The charged particle beam source 2 emits a charged particle beam that passes over the double octopole 3 and the collimating lens 4 before striking the aperture array 5. The array of pores then divides the beam into a plurality of charged particle beamlets that are gathered by the concentrator array 6. In the beam suppressor array 7, the individual beamlets may be suppressed, i.e., may be deflected such that they encounter the beam stop array 8 at a later stage of its trajectory rather than passing through the apertures in the beam stop array 8. The unsuppressed beamlets then pass through a deflector unit 9, which is adapted to provide scanning deflection of the beamlets in the X and/or Y directions. The deflector unit is typically a macro deflector that includes a conductive material that extends over its outer surface. At the end of its trajectory, the unsuppressed beamlets pass through the lens array 10, which is adapted to focus the beamlets onto the surface of the target 11. The beam stop array 8, deflector unit 9, and lens array 10 together form a projection lens assembly 12 that provides for suppression of beamlet blockage, scanning deflection of the plurality of beamlets, and shrinking of the unextinguished beamlets.

FIG. 1B shows an alternative optical column 31. The charged particle beam source 32 emits a charged particle beam that passes over the double octopole 33 and the collimating lens 34 before striking the aperture array 35. The array of pores then divides the beam into a plurality of charged particle beamlets that are gathered by the concentrator array 36. In beam suppressor array 37, the beamlets are split into a number of beamlets. Individual beamlets may be extinguished, i.e., may be deflected such that they encounter a beam stop array 38 at a later stage of their trajectory rather than passing through the apertures in the beam stop array 38. The unsuppressed beamlets are then passed through a deflector unit 39 which is adapted to provide scanning deflection of the beamlets in the X and/or Y directions. The deflector unit typically includes a micro-electro mechanical system (MEMS) component that is adapted to provide scanning deflection of the clusters of such beamlets. At the end of its trajectory, the unsuppressed beamlets pass through the lens array 40, which is adapted to focus the beamlets onto the surface of the target 41. The beam stop array 38, deflector unit 39, and lens array 40 together form a projection lens assembly 42 that provides for suppression of beamlet blocking, scanning deflection of the plurality of beamlets, and shrinking of the unextinguished beamlets.

Figure 1C schematically shows a detail of the optical column as shown in Figure 1B showing the trajectories of the three beamlets b1, b2, b3. A bundle of sub-beams from a charged particle beam source is emitted from aperture array 35 and is collected by concentrator array 36. The beamlets are in beam suppressor array 37 and then divided into beamlets b1, b2, b3, which are adapted to provide suppressed deflection for individual beamlets. In the illustrated figures, the beamlets b1, b2, b3 are each not provided with a suppression deflection such that the beamlets pass through a common aperture in the beam stop array 38. The unsuppressed beamlets are then scanned for deflection provided by deflector unit 39, which includes MEMS elements 39a and 39b that are adapted to provide scanning deflection for a plurality of beamlets. At the end of its trajectory, the unsuppressed beamlets pass through the lens array 40, which is adapted to focus the beamlets onto the surface of the target 41. The beam stop array 38, deflector unit 39, and lens array 40 together form a projection lens assembly 42 that provides for the blocking of the extinguished beamlets, the scanning deflection of the plurality of beamlets, and the reduction of the unextinguished beamlets.

2A shows a cross-sectional view of an embodiment of an improved projection lens assembly 200 in accordance with the present invention. The illustrated embodiment includes a housing having a conductive metallic perimeter wall portion 230 that is preferably metallic. The projection lens assembly further includes a cover member 210 and a support member 240 at a downstream end of the housing. The through opening 213 for the passage of the charged particle beamlets extends from the upstream surface of the cover member 210, through the interior of the projection lens assembly, toward the first electrode 201, through the support member 240, and finally into the second electrode 202. A plurality of charged particle beamlets can traverse the through opening before impacting the target 270. In the illustrated embodiment, the support member extends parallel to the first and second electrodes. Preferably, the support member extends radially away from the array of lens apertures in the first and second electrodes.

To avoid the formation of an electric field between the target and the projection lens assembly, both the target and the projection lens assembly can be connected to ground and/or electrically connected to each other. The structurally robust projection lens assembly in accordance with the present invention can be integrally placed in a known lithography system or can be swapped out or removed for maintenance purposes.

The plurality of charged particle beamlets first pass through the through passage 213 in the cover member 210. The body of the cover member 210 is made of a non-conductive material, although its upstream surface contains a conductive coating 211 and a portion of its downstream surface contains another conductive coating 212 that is used to form the lens assembly. The inner shield is protected from external electromagnetic influences. Preferably, the two conductive coatings are joined at the sides of the through opening to form a single continuous surface. Encapsulation rings 251 and 252 made of a non-conductive and preferably ceramic material will be encapsulated at the edges between the coatings and cover member 210 to reduce the chance of sparking at their edges.

Once the charged particle beamlets have passed the through opening, the charged particle beamlets pass through the deflector unit 220, which is adapted to provide a plurality of small beam scan deflections. The deflector unit can use a corresponding number of deflectors to deflect the charged particle beamlets any number of times. In a preferred embodiment, the deflector unit comprises X and Y deflectors. The leads 224a and 224b at the base 222 of the deflector unit and preferably the three-axis leads are adapted to carry control signals indicating whether the deflector unit is functioning properly. The deflector unit is substantially supported by the support member 240 and is preferably attached to the cover member 210 via a conductive adhesive connection 221. The deflector unit thus acts as a second support element that interconnects the cover element with the support element 240, thereby increasing the structural robustness of the assembly. It is advantageous to apply a conductive adhesive to facilitate the construction of the projection lens assembly, ie to allow for a widening of the tolerances, thus reducing the cost and effort of component manufacture on the one hand and lowering the component manufacturing on the other hand. Cost and workload. In accordance with a further understanding of this aspect of the invention, a slight change in the distance between the conductive coating 212 and the deflector unit 220 facing the downstream of the cover member 210 is by adhering the gap to a greater or lesser amount of conductive adhesion. The agent is filled to compensate. In a preferred embodiment, the adhesive is one in which it has a very low volatility in vacuum once cured and a corresponding (if not similar) coefficient of thermal expansion to its bonding surface. The base 222 of the deflector unit is mounted to an insulator 223 that electrically insulates the deflector unit from the first electrode 201. The first electrode 201 and the second electrode 202 each comprise an array of lens apertures, each lens aperture corresponding to a small beam of charged particles that may pass therethrough.

The support member 240 includes a layer 243 of non-conductive material, a first conductive coating 241 on the upstream facing surface of the support member, and a second conductive coating 242 on the downstream facing surface of the support member. The first and second conductive coatings are electrically isolated from one another. The first electrode 201 is a first conductive coating 241 that is electrically connected to the upstream facing surface of the support member. Leads 209a and 209b attached to the first coating are adapted to provide an electrical signal to the first electrode, and preferably such that a potential difference between the first and second electrodes generates an electric field to focus the charged particle beamlets, Wherein the potential difference between the electrodes is in the range of 4 kV. The second electrode 202 disposed on the surface facing the downstream of the support member 240 is electrically connected to the second conductive coating 242, which preferably covers all or most of the downstream facing surface. In a preferred embodiment, the second coating extends across the outer edge of the support member and is in conductive contact with the peripheral wall portion 230 of the outer casing. The surrounding wall portion and the first coating are thus electromagnetic shields adapted to provide at least a portion of the interior of the lens assembly.

Advantageously, the insulating layer 243 of the support member preferably comprising borosilicate glass is strong enough to substantially support the weight of the deflector unit, but thin enough to allow a strong and uniform electric field to be created between the first and second electrodes.

FIG. 2B shows an enlarged view of portion 260 of FIG. 2A. It can be clearly seen that the first and second coating layers 241, 242 that have been deposited on the insulating layer 243 are electrically isolated from each other by the insulating layer and by the gap 244. The gap 244 is filled with a non-conductive adhesive. Preferably, the adhesive used in the projection lens assembly has a low coefficient of thermal expansion. In order to prevent sparks from occurring at the corners of the first and second coating layers, the dielectric collapse protection structure 253 has been placed at the point of contact between the surrounding wall portion 230 and the support member 240. A small recess 246 in the insulating layer 243 at the through opening of the support member 240 serves to prevent sparks from occurring between the first and second electrodes and their corresponding coatings adjacent the through opening.

2C shows an alternate embodiment of a projection lens in which the weight of the deflector unit 220 is substantially fully supported by the support member 240, ie, the deflector unit is not supportedly coupled to the cover member 210. Preferably, the outer surface of the deflector unit is electrically connected to the conductive coating facing the downstream of the cover member by an isolating electrical lead 225 attached to the deflector unit by a detachable connector to ensure that the two are substantially identical Potential. In this embodiment, the cover element is removably attached to the surrounding wall portion 230. In another embodiment, the lead 225 is connected through a surrounding wall to a surface that faces upstream of the cover member.

Figure 2D shows an alternate embodiment of a projection lens assembly in accordance with the present invention. The second electrode 202 and the third electrode 203 are electrically connected to the outer casing and substantially at a ground potential. The first electrode 201 and the second electrode 202 are electrically insulated by the support member 240, and the first electrode 201 and the third electrode 203 are electrically insulated by the insulator 223. Leads 209a and 209b are attached to the first electrode 201 to provide an electrical signal to the first electrode, such that an electric field is generated between the first and second electrodes and between the first and third electrodes, which is used to Small beam focusing of charged particles. Typically, in this embodiment, the potential difference between the first electrode 201 and the second and third electrodes 202, 203 is in the range of -3,4 kV. The outer edge of the first electrode 201 is encapsulated by a non-conductive adhesive body for preventing spark formation at the outer edge of the first electrode 201.

3 shows a schematic cross-sectional view of an alternative projection lens assembly in accordance with the present invention. The projection lens assembly is constructed in a manner similar to the projection lens assembly shown in FIG. 2, and includes a third electrode 303 disposed upstream of the first electrode 301 in addition to the first electrode 301 and the second electrode 302. . The support member 340 has been reinforced with an adhesive strip 345 which is deposited on the first conductive coating 341. Preferably, adjacent elements are joined to one another using a suitable adhesive.

The third and first electrodes 303, 301 are separated by insulating spacers 324 and are electrically isolated from one another. The third electrode is electrically connected to the outer surface of the deflector unit 320 through the conductive beam stop array 322 and the conductive spacer 323. The outer surface of deflector unit 320, and thus third electrode 303, is preferably maintained at a fixed potential, for example, -4 kV with respect to ground. The second electrode 302 is transmitted through the second conductive coating 342 and is also electrically connected to the surrounding wall portion (not shown). Preferably, the peripheral wall portion and the second electrode 302 are maintained at substantially the same fixed potential as the patterned target, typically at ground potential. By changing the potential of the first electrode 301, the electric field between the first electrode and the third electrode 303 and the electric field between the first electrode 301 and the second electrode 302 can be changed. The potential of the first electrode can typically vary in the range of -4.3 kV. In this way, an electrostatic lens array is formed that is capable of producing an adaptable electric field to focus a plurality of charged particle beamlets.

In an alternate embodiment, the third electrode and the second electrode are substantially maintained at a ground potential, and the first electrode is maintained at a substantially fixed potential, eg, at -3,4 kV with respect to the third electrode and the second electrode . In this embodiment, an insulating spacer 324 that electrically insulates the first electrode from the third electrode is preferably formed by applying an electrically insulating adhesive between the first electrode and the third electrode.

4A shows a cross-sectional view of the projection lens assembly of FIG. 2B along line A-A. The support member 240 that extends radially away from the array of lens apertures of the first electrode 201 and the second electrode 202 (not shown) includes a first conductive coating 241 on its upstream surface. The surrounding wall portion 230 is shown in more detail in the same manner as the dielectric protection structure 253. The upstream surface of the support member 240 is provided with a radially extending strip of adhesive 245 which further enhances the supportability of the support member. If the preferably non-conductive adhesive strip is disposed on the surface facing the downstream of the support member, it must be noted that the ridges of the strip do not protrude beyond the second electrode in the downstream direction. The second electrode can then still be placed very close to the target.

4B shows a top view of the projection lens assembly of FIG. 2A with the through openings 213 for the plurality of beamlets, the dielectric collapse guard ring 251, and the upstream facing cover layer 210 facing the conductive coating 211 visible. A ring 251, preferably comprising a non-conductive ceramic material, encloses the outer edge of the conductive coating 211 upstream to prevent spark formation at the edge.

A schematic diagram of a charged particle beamlet trajectory in one embodiment of a projection lens assembly in accordance with the present invention is set forth in Figure 5A. In this embodiment, the beam stop array 522 has been disposed between the deflector unit 520 and the third electrode 503. The beamlets 510a, 510b, and 510c pass through a deflector unit 520 that is adapted to provide scanning deflection of the beamlets in the X and/or Y directions. The deflector plate 527, which is covered by the conductive outer surface of the deflector unit 520, is electrically isolated from the outer surface of the deflector unit by a spacer that includes the isolating material 526.

The beamlets 510a have been inhibited from deflecting before reaching the deflector unit, and thus are directed to the non-small beam pass region of the beam stop array 522. The unsuppressed beamlets 510b and 510c pass over the deflector unit and are deflected near their respective pivot points Pb and Pc, the pivot points Pb and Pc being in substantially the same plane as the beam stop array 522. Since the pivot points of the individual beamlets are in substantially the same plane as the beam stop array, the unsuppressed beam spot does not move over the beam stop array, ie the deflection by the deflector unit does not substantially affect the unsuppressed small The intensity distribution of the beam at its corresponding pivot point. The unsuppressed beamlets 510b and 510c then pass through the lens apertures in the first and second electrodes 501, 502, the electric field 505a is generated between the first electrode 501 and the second electrode 501 and is adapted to focus the charged particles Go to goal 570. The electrodes are separated by spacers 523, 524, and 525. Because the beam stop array and beamlet pivot point in this configuration can be positioned relatively close to the lens electrode, especially if the beam stop array is placed closer to the lens electrode upstream of the deflector unit. Plane, significantly reducing beam aberrations. This creates a clearer defined beam spot on the target and allows the target to be patterned at a higher resolution.

FIG. 5B shows an alternate embodiment of a projection lens assembly in accordance with the present invention in which beam stop array 522 is disposed upstream of deflector unit 520. The charged particle beamlet 510a has been inhibited from deflecting before reaching the beam stop array, and thus impinges on its non-beamlet passing region. Charged particle beamlets 510b and 510c stop array 522 through the beam and are deflected by scanning by deflector unit 520. The beamlets are then focused using electrodes 501, 502, 503 prior to striking target 570. Because the second electrode 502 forms the downstream end of the projection lens assembly, the charged particle beamlets can have their pivot points positioned very close to the target 570 and remain substantially unfocused with respect to scan deflection.

FIG. 6 shows an embodiment of an improved projection lens assembly 600 in accordance with the present invention. The illustrated embodiment includes a housing having a conductive metallic perimeter wall portion 230 that is preferably metallic. The projection lens assembly further includes a cover member 210 that substantially covers the opening at the upstream end of the housing. The through opening 213 for the passage of the charged particle beamlets extends from the upstream surface of the cover member 210, through the interior of the projection lens assembly, toward the first electrode 201, through the non-conductive spacer 215, and finally into the second electrode 202. . A plurality of charged particle beamlets can traverse the through opening before impacting the target 270.

To avoid the formation of an electric field between the target and the projection lens assembly, both the target and the projection lens assembly can be connected to ground and/or electrically connected to each other. The projection lens assembly according to the present invention can be integrally placed in a known lithography system or can be swapped out or removed for maintenance purposes.

The plurality of charged particle beamlets first pass through the through passage 213 in the cover member 210. The body of the cover member 210 is made of a non-conductive material, although its upstream surface includes a conductive surface 211 and a portion of its downstream surface includes another conductive surface 212 that is used to shield the inside of the lens assembly. To avoid external electromagnetic influences. Preferably, the two conductive surfaces meet at the sides of the through opening to form a single continuous surface. Encapsulation rings 251 and 252 made of a non-conductive and preferably ceramic material will be encapsulated at the edges between the electrically conductive surfaces and the cover member 210, thereby reducing the chance of spark formation at their edges.

Once the charged particle beamlets have passed the through opening of the cover element, the charged particle beamlets pass through the beam optics 217, which directs the plurality of beamlets to the target 270. In the illustrated embodiment, the beam optics includes a deflector unit 220 having a base 222 mounted on the non-conductive spacer 223, and the beam optics further includes a first electrode 201, a non-conductive spacer 215, and a second electrode 202. . Transducer unit 220 is a scan deflection suitable for providing the plurality of beamlets. The deflector unit can use a corresponding number of deflectors to deflect the charged particle beamlets any number of times. In a preferred embodiment, the deflector unit comprises X and Y deflectors. The leads 224a and 224b at the base 222 of the deflector unit and preferably the three-axis leads are adapted to carry control signals indicating whether the deflector unit is functioning properly. The beam optics are substantially supported by the cover member 210 and attached to the cover member 210 via a conductive adhesive connection 221. In accordance with a further understanding of this aspect of the invention, the change in distance between the facing conductive surface 212 and the deflector unit 220 downstream of the cover member 210 can be projected by adjusting the height of the conductive adhesive body 221 that will fill the gap. Compensation is made during the construction of the lens assembly. In a preferred embodiment, the adhesive is one in which it has a very low volatility in vacuum once cured and a corresponding (if not similar) coefficient of thermal expansion to its bonding surface. The base 222 of the deflector unit is mounted to an insulator 223 that electrically insulates the deflector unit from the first electrode 201. Both the first electrode 201 and the second electrode 202 comprise an array of lens apertures, each lens aperture of the array being corresponding to a small beam of charged particles that may pass therethrough.

The lead 209 is attached to the first electrode 201 and is adapted to provide an electrical signal to the first electrode, preferably such that the potential difference between the first and second electrodes 201, 202 is in the range of 4 kV, the potential difference An electric field is generated to focus the charged particle beamlets. The second electrode 202 disposed on the surface facing the downstream of the positioning member 240 is electrically connected to the surrounding wall portion 230 by the conductive wiring 218.

Typically, once the beam optics have been assembled, the height of the beam optics cannot be adjusted, which in this example is the distance from the downstream end of the second lens array 202 to the upstream end of the deflector unit 220. However, according to the method of the present invention, the total distance from the end edge of the second electrode to the upstream surface of the covering member can be adjusted relatively easily by changing the height of the adhesive body 221 which brings the two together. . The adhesive can be thoroughly injected to fill the gap between the beam optics and the cover member during the construction of the projection lens assembly using additional through openings 214a, 214b in the cover member 210.

FIG. 7 shows an alternate embodiment of a projection lens assembly 700 in accordance with the present invention. In this embodiment, beam optics 717 does not include a deflector unit for providing scan deflection of the plurality of charged particle beamlets. The deflector unit can be placed upstream of the projection lens assembly in the lithography system. Beam optics 717 includes a first electrode 201 and a second electrode 202 separated by a non-conductive spacer 215, which also forms part of the beam optics. The first electrode 201 is electrically connected to the downstream facing surface of the cover member 210. The connection between the surface facing the downstream including the conductive surface 212 and the first electrode is formed by the conductive adhesive body 221. Lead 218 electrically connects second electrode 202 to surrounding wall portion 230 such that both are grounded. Especially when the electrodes are thin and placed close to each other to provide a strong and uniform electric field, the height of the adhesive body is an important factor in the height of the entire projection lens assembly. During the construction of the projection lens assembly, this height can be easily adjusted to a desired height by varying the height of the adhesive body.

FIG. 8A shows an alternate embodiment of a projection lens assembly similar to that shown in FIG. 6, which further includes positioning elements 249a, 249b. In the downstream opening adjacent the outer casing, the beam optics are substantially aligned in a direction perpendicular to the through opening by means of the positioning elements 249a, 249b. In addition to providing additional stability in the position of the beam optics relative to the housing, the positioning elements may also facilitate the construction of the projection lens assembly, i.e., simplify alignment of the beam optics perpendicular to the direction of the through opening. In this embodiment, the positioning elements comprise an elongated, thin, and substantially rigid structure, and are preferably attached to the peripheral wall portion 230 and the beam optics 217 using an electrically conductive adhesive. In the illustrated embodiment, the locating element comprises a conductive material and is attached to the second electrode 202 and the surrounding wall portion 230, thus maintaining the same potential. The positioning elements 249a, 249b maintain a substantially fixed distance between the otherwise freely depending end of the beam optic and the surrounding wall portion, improving the structural integrity of the projection lens assembly and limiting the second electrode 202 relative to the surrounding wall portion. Translation and/or oscillatory motion. In an alternate embodiment, the positioning element is used only during the construction of the projection lens assembly and is not present in the finished product.

Figure 8B shows a top view of the projection lens assembly of Figure 6 taken along the line indicated by line A, i.e., the outermost peripheral region of the cover member 210 is not shown. Moving in a radially outward direction from the through opening 213 of the cover member 210, the upstream conductive surface 211 can be seen as surrounding the additional through openings 214a, 214b. The additional through opening is disposed around the through opening 213 and facilitates passage of the injection needle or the like to deposit the adhesive body between the downstream facing surface of the cover member and the upstream facing surface of the beam optic. Moving further outward, the edge between the upstream conductive surface 211 and the non-conductive portion of the cover member 210 is encapsulated by an encapsulation ring 252 of non-conductive material to reduce the chance of sparking at the edge. .

Figure 8C shows a bottom view of the projection lens assembly of Figure 6 taken along the line indicated by line A. The second electrode 202 is electrically connected to the surrounding wall portion 230 by positioning elements 249a, 249b. Behind the second electrode 202, portions of the non-conductive spacers 215 can be seen as if portions of the additional through openings 214a, 214b were visible. These additional through openings enter the conductive surface 212 of the cover member 210, which enhances the electromagnetic shielding properties of the projection lens assembly. The edge between the conductive surface 212 and the non-conductive portion of the cover member 210 is encapsulated by an encapsulation ring 252 to prevent sparks from occurring at the edge. The positioning elements 249a, 249b extend substantially perpendicular to the direction of the through opening 213 and are substantially fixed in a plane along which the beam optic is positioned. In other words, when the second electrode 202 and the positioning elements 249a, 249b are in a horizontal orientation, the positioning element substantially limits the horizontal movement of the beam optic relative to the surrounding wall. Since the positioning element limits movement along its extension direction, slight adjustments in the distance between the beam optics and the cover element can be made even when the positioning elements have been fixedly attached to the beam optics and the cover element . In an alternate embodiment, the locating element can be formed from a diaphragm that is fixedly attached to the beam optics and the cover element in an orientation substantially perpendicular to the direction of the through opening and is adapted to position the beam optics At a substantial fixed distance from the surrounding wall.

Figure 9 shows a schematic cross-sectional view of an alternative projection lens assembly in accordance with the present invention. The projection lens assembly is constructed in a manner similar to the projection lens assembly shown in FIG. 8A, and includes, in addition to the first electrode 301 and the second electrode 302, a third electrode 303 also having an array of apertures, which is disposed in The upstream of the first electrode 301. Preferably, adjacent elements are joined to one another using a suitable adhesive.

The third and first electrodes 303, 301 are separated by insulating spacers 324 and are electrically isolated from one another. The third electrode is electrically connected to the outer surface of the deflector unit 320 through the conductive beam stop array 322 and the conductive spacer 323. The outer surface of deflector unit 320, and thus the third electrode, is preferably maintained at a fixed potential, for example, -4 kV with respect to ground. The second electrode 302 is electrically connected to the surrounding wall portion (not shown) via the positioning members 349a and 349b and is insulated and spaced apart from the first electrode 301 by the non-conductive spacer 315. The locating elements are used to align the downstream end of the beam optics along a plane spanned by the second electrode, i.e., in the illustrated orientation, the locating elements horizontally align the downstream end of the beam optics. The non-conductive spacer 315 is provided with a stepped portion 346 that lengthens the path from the first electrode to the second electrode along the surface of the spacer 315. This lengthened path length is an opportunity to help reduce sparking between the first and second electrodes.

The peripheral wall portion and the second electrode 302 are preferably maintained at substantially the same fixed potential as the target to be patterned, typically at ground potential. By changing the potential of the first electrode 301, the electric field between the first electrode 301 and the third electrode 303 and the electric field between the first electrode 301 and the second electrode 302 can be changed. The potential of the first electrode can typically vary in the range of -4.3 kV. In this way, an electrostatic lens array is formed that is capable of producing an adaptable electric field to focus a plurality of charged particle beamlets.

A schematic diagram of a charged particle beamlet trajectory in one embodiment of a projection lens assembly 700 in accordance with the present invention is set forth in FIG. In this embodiment, the beam stop array 522 has been disposed between the deflector unit 520 and the third electrode 503. The beamlets 510a, 510b, and 510c pass through a deflector unit 520 that is adapted to provide scanning deflection of the beamlets in the X and/or Y directions. The deflector plate 527, which is covered by the conductive outer surface of the deflector unit 520, is electrically isolated from the outer surface of the deflector unit by a spacer comprising an insulating material 526.

The beamlets 510a have been inhibited from deflecting before reaching the deflector unit, and thus are directed to the non-small beam pass region of the beam stop array 522. The unsuppressed beamlets 510b and 510c pass over the deflector unit and are deflected near their respective pivot points Pb and Pc, the pivot points Pb and Pc being in substantially the same plane as the beam stop array 522. Since the pivot points of the individual beamlets are in substantially the same plane as the beam stop array, the unsuppressed beam spot does not move over the beam stop array, ie the deflection by the deflector unit does not substantially affect the unsuppressed small The intensity distribution of the beam at its corresponding pivot point. The unsuppressed beamlets 510b and 510c then pass through the lens apertures in the first and second electrodes 501, 502, the electric field 505a is generated between the first electrode 501 and the second electrode 501 and is adapted to focus the charged particles Go to goal 570. The electrodes are separated by spacers 523, 524, and 515. Because the beam stop array and beamlet pivot point in this configuration can be positioned relatively close to the electrodes, especially if the beam stop array is placed upstream of the deflector unit and is closer to The plane across which the electrodes traverse significantly reduces beam aberrations. This creates a clearer defined beam spot on the target and allows the target to be patterned at a higher resolution.

11 shows an alternate embodiment of a projection lens assembly in accordance with the present invention in which beam stop array 522 is disposed upstream of deflector unit 520. The charged particle beamlet 510a has been inhibited from deflecting before reaching the beam stop array, and thus impinges on its non-beamlet passing region. Charged particle beamlets 510b and 510c stop array 522 through the beam and are deflected by deflection by deflector unit 520. The beamlets are then focused using electrodes 501, 502, 503 prior to striking target 570. Because the second electrode 502 forms the downstream end of the projection lens assembly, the charged particle beamlets can have their pivot points positioned very close to the target 570 and remain substantially unfocused with respect to scan deflection. In the illustrated embodiment, although the small beam scanning deflection is performed using a macro deflector adapted to provide two electric fields, in an alternate embodiment, the deflector unit may be provided The plurality of electric fields used for the scanning deflection of the beamlets, for example, each beamlet is one or more electric fields, as shown in Figure 1A, or each group of beamlets is one or more electric fields.

Figure 12A shows a flow chart for assembling the method of some of the above embodiments. In step 901, the beam optics are aligned with the through opening of the cover member such that the beam optics and the cover member are at a predetermined distance from each other. Next, in step 902, the aligned cover element is attached to the upstream end of the outer casing such that it partially overlaps the upstream edge of the outer casing. In step 903, the gap between the beam optic and the cover member is filled with an adhesive body to substantially support the beam optic to the cover member. Finally, at step 904, the adhesive body is allowed to cure. Such an approach allows for a more convenient manufacturing of such projection lens assemblies, and such methods can be used to more accurately calibrate the dimensions of such projection lens assemblies.

Figure 12B shows an alternate embodiment of the method in which the distance between the cover member of the projection lens assembly and the downstream end edge of the beam optics is made during the construction of the projection lens assembly prior to curing of the adhesive in step 903b. Adjustment. This method allows the distance to be adjusted to a predetermined value. During this adjustment step, it is possible to measure the beam focusing properties, for example by configuring the beam profile sensor for the plurality of beamlets downstream of the projection lens assembly during construction and measuring the distance when adjusting the distance Corresponding to the beam profile. In an alternate embodiment, the distance is adjusted to a predetermined value.

In summary, the present invention discloses a projection lens assembly for directing a plurality of charged particle beamlets onto an image plane that is positioned in a downstream direction, and a method for assembling such a projection lens assembly. In particular, the present invention discloses a modular projection lens assembly having improved structural integrity and/or improved placement accuracy of its most downstream electrodes.

It is to be understood that the above description is included to illustrate the preferred embodiments and is not intended to limit the scope of the invention. From the above discussion, many variations will be apparent to those skilled in the art, and are still to be covered by the spirit and scope of the invention. For example, the principles of the present invention can also be applied to projection lens assemblies for directing one or more beams onto an image plane. In this case, the light optics can be used in place of the electrodes, and the light modulator can be replaced with a light modulator. As still another example, a plurality of beamlets can pass through the same apertures in the array of lens apertures of the first and second electrodes. Furthermore, the projection lens assembly according to the present invention may comprise any number of electrodes greater than or equal to two without departing from the scope of the invention.

1. . . Optical column

2. . . Charged particle beam source

3. . . Double eight pole

4. . . Collimating lens

5. . . Pore array

6. . . Concentrator array

7. . . Beam suppressor array

8. . . Beam stop array

9. . . Deflector unit

10. . . Lens array

11. . . aims

12. . . Projection lens assembly

31. . . Optical column

32. . . Charged particle beam source

33. . . Double eight pole

34. . . Collimating lens

35. . . Pore array

36. . . Concentrator array

37. . . Beam suppressor array

38. . . Beam stop array

39. . . Deflector unit

39a-b. . . MEMS component

40. . . Lens array

41. . . aims

42. . . Projection lens assembly

200. . . Projection lens assembly

201. . . First electrode

202. . . Second electrode

203. . . Third electrode

209, 209a, 209b. . . lead

210. . . Covering component

211, 212. . . Conductive coating

213. . . Through opening

214ab. . . Additional through opening

215. . . Spacer

217. . . Beam optics

218. . . lead

220. . . Deflector unit

221. . . Conductive adhesive body

222. . . Base

223. . . Insulator

224a, 224b, 225. . . lead

226-a-b. . . Non-conductive adhesive body

227. . . Electrical connection to the outer casing

230. . . Surrounding wall

240. . . Supporting element

241. . . First conductive coating

242. . . Second conductive coating

243. . . Non-conductive material layer

244. . . gap

245. . . Adhesive strip

246. . . Concave

249a, 249b. . . Positioning element

251, 252. . . Encapsulation ring

253. . . Dielectric collapse protection structure

260. . . section

270. . . aims

301. . . First electrode

302. . . Second electrode

303. . . Third electrode

315. . . Non-conductive spacer

320. . . Deflector unit

322. . . Beam stop array

323. . . Conductive spacer

324. . . Insulating spacer

340. . . Supporting element

341. . . First conductive coating

342. . . Second conductive coating

343. . . Insulation

345. . . Adhesive strip

346. . . Stepped part

349a, 349b. . . Positioning element

501. . . First electrode

502. . . Second electrode

503. . . Third electrode

505a. . . electric field

510a, 510b, 510c. . . Small bunch

511. . . Conductive coating

513. . . Through opening

514a-b. . . Additional through opening

515. . . Spacer

517. . . Beam optics

520. . . Deflector unit

521. . . Conductive adhesive body

522. . . Beam stop array

523, 524, 525. . . Spacer

526. . . Isolation material

527. . . Deflector plate

551. . . Encapsulation ring

570. . . aims

600. . . Projection lens assembly

700. . . Projection lens assembly

717. . . Beam optics

901-904. . . Process for producing a method according to an embodiment of the present invention

B1-b3. . . Small bunch

Pa-Pc. . . Pivot point

The invention has been described based on the exemplary embodiments shown in the drawings, in which:

Figure 1A shows a schematic diagram of a prior art charged particle exposure system;

Figures 1B and 1C show schematic diagrams of alternative charged particle exposure systems and details thereof;

2A shows a cross-sectional view of an embodiment of a projection lens assembly in accordance with the present invention;

Figure 2B shows an enlargement of portion 260 of Figure 2A;

2C shows a cross-sectional view of an alternate embodiment of a projection lens assembly;

2D shows a cross-sectional view of still another alternative embodiment of a projection lens assembly;

Figure 3 shows a cross-sectional view of an alternative electrode configuration of a projection lens assembly in accordance with the present invention;

4A and 4B respectively show a cross-sectional view along line A-A of Fig. 2B and a top view of the projection lens assembly;

Figure 5A shows a schematic cross-sectional view of a projection lens assembly in accordance with the present invention with a beam stop disposed between the deflector unit and the electrode;

Figure 5B shows a schematic cross-sectional view of a projection lens assembly in accordance with the present invention with a beam stop disposed upstream of the deflector unit;

6 shows a schematic cross-sectional view of an embodiment of a projection lens assembly in accordance with yet another embodiment of the present invention;

Figure 7 shows a schematic cross-sectional view of still another embodiment of a projection lens assembly in accordance with the present invention;

8A, 8B and 8C respectively show schematic cross-sectional, top and bottom views of still another embodiment of a projection lens assembly in accordance with the present invention;

Figure 9 shows a cross-sectional schematic view of a portion of still another embodiment of a projection lens assembly in accordance with the present invention;

Figure 10 shows a schematic cross-sectional view of a portion of a projection lens assembly in accordance with the present invention;

Figure 11 shows a schematic cross-sectional view of a portion of a projection lens assembly in accordance with the present invention;

12A and 12B show a flow chart of an embodiment of a method in accordance with the present invention.

200. . . Projection lens assembly

201. . . First electrode

202. . . Second electrode

209, 209a, 209b. . . lead

210. . . Covering component

211, 212. . . Conductive coating

213. . . Through opening

220. . . Deflector unit

221. . . Conductive adhesive connection

222. . . Base

223. . . Insulator

224a-b. . . lead

240. . . Supporting element

251, 252. . . Encapsulation ring

260. . . section

270. . . aims

Claims (18)

A projection lens assembly for directing a plurality of charged particle beamlets onto an image plane, the projection lens assembly including a first electrode for focusing a beam of one or more charged particles of the plurality of charged particle beamlets And a second electrode, and a housing comprising a through opening for allowing the plurality of charged particles to pass through; the first and second electrodes each comprise an array of lens apertures aligned with the through opening to allow the plurality Passing a small beam of one or more charged particles of charged particle beamlets; characterized in that the outer casing comprises a surrounding wall portion and has upstream and downstream end edges; and the projection lens assembly further comprises: at least one support element, which is included for allowing a plurality of through openings through which the charged particles pass, wherein the at least one support member is attached to the outer casing; and wherein the first electrode and the second electrode are supported by the at least one support member, wherein the first The second electrode is disposed in or near the plane defined by the downstream end edge of the outer casing. The projection lens assembly of claim 1, wherein the first electrode and the second electrode are attached to the support member by an adhesive connection. The projection lens assembly of claim 1 or 2, wherein the support member is composed of a non-conductive material. A projection lens assembly according to claim 1 or 2, comprising one or both of the downstream and upstream end edges of the one or more support members. The projection lens assembly of claim 1 or 2, wherein the second electrode is formed at an end of the projection lens assembly in the downstream direction. The projection lens assembly of claim 1, wherein the first and second electrodes are respectively disposed on an upstream surface and a downstream surface of the support member, the first electrode is spaced apart from the peripheral wall portion, and the The support element is bridged between the first electrode and the surrounding wall. The projection lens assembly of claim 6, wherein the upstream surface of the support member is at least partially covered by a first conductive coating connected to the first electrode. The projection lens assembly of claim 6 or 7, wherein the downstream surface of the support member is substantially covered by a second electrically conductive coating attached to the second electrode. The projection lens assembly of claim 8 wherein the second coating extends radially from the outer opening on the downstream surface of the support member to the upstream surface of the support member An outer peripheral region, and the first coating extends radially outward from a through opening on an upstream surface of the support member. The projection lens assembly of claim 1 or 2, further comprising: a third electrode positioned upstream of the first electrode, wherein. The third electrode and the second electrode are each maintained at a fixed potential, and wherein the potential of the first electrode is adapted to a predetermined focus toward the beam of charged particles. The projection lens assembly of claim 8, wherein the peripheral wall portion is electrically conductive and electrically connected to the second coating layer. The projection lens assembly of claim 1 or 2, wherein the support member faces the downstream surface and/or the surface facing the upstream is cured The strip of adhesive material is reinforced and is preferably a radially extending strip. The projection lens assembly of claim 1 or 2, wherein the support member, the first and second electrodes are substantially planar. The projection lens assembly of claim 1 or 2, wherein the at least one support member comprises a first support member, a second support member, and a cover member each having a through opening for a plurality of charged particle beamlets, wherein The cover element is disposed at an upstream end edge of the peripheral wall portion, wherein the second support member interconnects the cover member with the first electrode or the first support member. The projection lens assembly of claim 14, wherein the second support member comprises a deflector unit. The projection lens assembly of claim 15 wherein the deflector unit is adapted to deflect a plurality of charged particle beamlets near their associated pivot points, the associated pivot point being substantially the same as the beam stop array The plane. A projection lens assembly according to claim 15 or 16, comprising: a beam stop array disposed upstream of the deflector unit, the deflector unit being adapted to pivot a plurality of charged particle beamlets in association therewith Deflection near the point, the associated pivot point is substantially in the plane between the first and second electrodes. A method for assembling a projection lens assembly for directing a plurality of charged particle beamlets onto an image plane, the projection lens assembly comprising: a housing comprising a surrounding wall and having upstream and downstream end edges Beam optics comprising a small beam for the plurality of charged particles a first electrode and a second electrode that are focused by one or more charged particles; and a covering member; the housing and the covering member include a through opening for allowing the plurality of charged particles to pass through, and the first and the first The two electrodes each comprise an array of lens apertures for allowing passage of the one or more charged particles of the plurality of charged particle beamlets; wherein the covering element is adapted to substantially cover an upstream edge of the housing; wherein the method comprises the steps : aligning the beam optic with the through opening of the cover element such that the plurality of charged particle beamlets are passable and the beam optic is separated from the cover element by a gap; the cover element is fixed To the outer casing, the covering element is overlapped with the upstream edge of the outer casing; a gap between the beam optic and the covering element is filled with an adhesive body to substantially support the beam optic to the covering element; the adhesive body is Cured.