Projection exposure apparatus, and method for designing component of projection exposure apparatus

Abstract

To provide a component of a projection exposure apparatus.SOLUTION: A component 30 includes an optical element 31 and an actuator 35, the optical element and the actuator are connected with each other by force so as to be fixed, and the actuator is constituted so as to at least locally deform the optical element. Further, a method for designing a component includes: a step of designing an actuator; a step of obtaining parasitic deformation of the optical element caused by an operation or a difference of thermal expansion coefficients of the optical element and the actuator; a step of considering a combined effect of scanning exposure used in a projection exposure apparatus to obtain a parasitic aberration on the basis of the parasitic deformation; a step of optimizing the actuator on the basis of the obtained parasitic aberration; and a step of repeating at least a few of process steps until the value of the parasitic aberration becomes below a predetermined value.SELECTED DRAWING: Figure 4a

Description

[Technical Field]

[0001] This application claims priority from German Patent Application No. 10 2021 205 368.8 filed on May 27, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] The invention relates to a component of a projection exposure apparatus for semiconductor lithography and to a method for designing said component, in particular for minimizing the adverse effects of parasitic deformations caused by actuators on the imaging quality of the projection exposure apparatus. [Background technology]

[0003] In a projection exposure apparatus for semiconductor lithography, a lithographic mask, also known as a reticle, e.g. a phase mask, is imaged onto a semiconductor substrate, also known as a wafer, using optical elements such as lens elements and / or mirrors.

[0004] In particular to achieve high resolution in lithography optical units, EUV light, for example with wavelengths in the range of 1 nm to 120 nm, especially 13.5 nm, has also been used in recent years compared to conventional systems with typical wavelengths of 365 nm, 248 nm or 193 nm.

[0005] The optical elements used in this case are in particular mechanically manipulated in order to improve the imaging quality and to correct disturbances that occur during operation, and a distinction must be made between a pure shift of the optical element and a deformation of the optical element.

[0006] In the case of a deformable mirror, actuators, for example in the form of an actuator matrix, are glued or bonded to the back side of the mirror to create the mechanical connection for targeted deformation.

[0007] Actuator matrices are known from the prior art, which are embodied in the form of a rectangular plate and comprise a plurality of interconnected actuator pads. The individual actuator pads are typically rectangular or triangular and comprise holes that are typically located at the corners or sides of the actuator pads, which have the function of allowing the actuator pads to be in contact with a controller. Physical stiffness losses of the combination of actuator and optical element occur all around the actuator, i.e., around the outer edges and holes of the plate of the actuator matrix, which losses lead to parasitic deformations in the surrounding areas during operation or due to differences in thermal expansion, for example due to differences in thermal expansion coefficients. This has a negative impact on the imaging quality of the projection exposure apparatus.

[0008] Due to the scanning operation mode of today's lithography systems, i.e., movement of the phase mask under the illumination slit and movement of the wafer in the opposite direction, the adverse effects become even more pronounced, as the aberrations caused by the above parasitic deformations can accumulate along the scanning direction. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to provide a component that eliminates the above-mentioned drawbacks of the prior art.A further object of the present invention consists in specifying a method for designing said component. [Means for solving the problem]

[0010] This object is achieved by a component and a method having the features of the independent claims. The dependent claims relate to advantageous developments and variations of the invention.

[0011] A component of a projection exposure apparatus for semiconductor lithography according to the invention comprises an optical element and an actuator. The optical element and the actuator are force-fittingly connected to one another, the actuator being configured to at least locally deform the optical element. According to the invention, the actuator is embodied in such a way that the influence of stiffness losses in the periphery defining the actuator on the imaging quality is minimized. The force-fitting connection between the actuator and the optical element, such as a mirror, can be realized by adhesive or bonding, or by a releasable connection, such as a screw connection.

[0012] In the first embodiment of the present invention, the actuator may be implemented in the form of an actuator matrix including at least two actuator pads, and the actuator matrix typically includes 9 to 30 actuator pads.

[0013] In particular, the cumulative length of the periphery of the actuator extending on an axis parallel to the scanning direction used in the projection exposure apparatus can be minimized, which is advantageous for scanning exposure methods used in projection exposure apparatuses, since in this case some optical effects of disturbances extending perpendicular to the scanning direction, such as parasitic deformations, are averaged out and minimized by the scanning movement.

[0014] Furthermore, the periphery of the actuator is oriented at an angle at least partially relative to the scanning direction, so that the total scanning movement of the part of the periphery extending in the scanning direction is advantageously minimized.

[0015] In particular, the actuator includes a serpentine peripheral contour relative to the scanning direction, which can be achieved, for example, by the actuator pads being hexagonal and arranging the actuator pads in rows shifted by half the width of the actuator pad, with protrusions of the actuator pads projecting into recesses in adjacent pads.

[0016] Furthermore, the linear perimeter structure of the actuator can be oriented at an angle relative to the scanning direction. This has the advantage that the perimeter defining the actuator does not have any aligned portions in the scanning direction. However, consideration must be given to the structural effects that the tilt of the actuator may have on the deformation effect of the actuator on the optically active surface.

[0017] In particular, the contact holes for the actuator pads formed in the actuator matrix can be designed to reduce the cumulative length of the edge portions of the holes extending on an axis parallel to the scanning direction used in the projection exposure apparatus.

[0018] This can be achieved, for example, by minimizing the area of ​​at least some of the holes, thereby reducing the cumulative total length of all hole edges. Holes can be formed in corners, sides, within the active surface of the actuator pad, or a combination of these areas. The size of the holes is determined by the space required for contact.

[0019] Furthermore, the holes can be positioned such that the number of holes positioned on an axis extending parallel to the scanning direction is minimized, thus minimizing the parasitic aberrations accumulated due to the scanning motion. The number of holes positioned on an axis can be reduced, for example, by strategically positioning the holes relative to the actuator pads as described above.

[0020] In yet another embodiment of the present invention, the actuator pads can have a triangular, rectangular, or hexagonal geometric shape. In addition to the geometric shape of the actuator pads, the number of rows and columns of the actuator matrix formed by the actuator pads can also be freely selected, so that matrices with, for example, 3 rows and 3 columns to 5 rows and 5 columns or more are conceivable. The number of rows and columns does not have to be the same, so a matrix with 4 rows and 6 columns can also be formed.

[0021] In yet another embodiment of the invention, the actuator may have a separately controllable section for compensating for stiffness losses, which allows the stiffness of the entire system of actuator pads and mirror material, which varies in the region of the intermediate space, to be taken into account by correspondingly changing the control of said section, thus reducing undesired movements / deformations and avoiding possible resulting image errors.

[0022] In particular, the portion may be formed as a peripheral actuator pad of actuator pads arranged in a peripheral region of the actuator matrix, controllable independently of a second region of actuator pads formed as partial actuator pads, and configured to compensate for parasitic deformations caused by stiffness losses, the peripheral actuator pads increasing the deformation effect at the periphery compared to undivided actuator pads and thus compensating for stiffness losses.

[0023] A method according to the invention for designing a component of a projection exposure apparatus in order to minimize the effects of parasitic deformations on the imaging quality of a projection exposure apparatus comprising an optical element and an actuator, when deformations of the optical element are caused by an actuator, comprises: designing an actuator; determining parasitic deformations of the optical element caused by actuation or by differences in the thermal expansion coefficients of the optical element and the actuator; determining parasitic aberrations based on the parasitic deformations, taking into account the summation effect of scanning exposures used in the projection exposure apparatus; optimizing the actuator based on the determined parasitic aberrations; repeating at least some of the previous process steps until the value of the parasitic aberration is below a predetermined value; Includes.

[0024] The parasitic deformations can be determined, for example, by FEM simulation or by optical measurement techniques on the optically active surface of the optical element. The parasitic aberrations can be determined by simulation based on the parasitic deformations or by measurements at component level or for the entire system, i.e., in the projection exposure apparatus.

[0025] Furthermore, at least a portion of the actuator travel can be used to correct for parasitic deformations, this self-correction having the known advantage of compensating for errors at the location where they occur.

[0026] Furthermore, when determining the resulting parasitic aberrations, further measures for optimizing the imaging quality present in the projection exposure apparatus can be taken into account.

[0027] In particular, the means can be embodied in the form of a manipulator for positioning or deforming further optical elements of the projection exposure apparatus. Usually, substantially all optical elements of a projection exposure apparatus are manipulable, so that many additional correction means are available.

[0028] Furthermore, a means can be embodied in the form of a simulation-based algorithm for predicting the imaging quality taking into account a number of influencing parameters and determining the required manipulator movements.

[0029] Exemplary embodiments and variants of the invention are explained in more detail below with reference to the drawings. [Brief explanation of the drawings]

[0030] [Figure 1] 1 shows a schematic meridian section of a projection exposure apparatus for EUV projection lithography; [Figure 2] 1 shows a schematic meridional section of yet another projection exposure apparatus for DUV projection lithography; [Figure 3a] 1 shows components known from the prior art; [Figure 3b] A wavefront diagram is shown. [Figure 4a] 1 shows a first embodiment of a component according to the invention; [Figure 4b] A wavefront diagram is shown. [Figure 5] 1 shows a detailed view of a component according to the present invention; [Figure 6] 3 shows yet another embodiment of a component according to the present invention. [Figure 7] 1 shows a detailed view of the present invention. [Figure 8] 3 shows a flowchart of a method for designing a component according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] The essential components of a microlithography projection exposure apparatus 1 will first be described by way of example with reference to Figure 1. It should be understood that the description here of the basic structure of the projection exposure apparatus 1 and its components is not limiting.

[0032] In addition to the radiation source 3, an embodiment of the illumination system 2 of the projection exposure apparatus 1 comprises an illumination optical unit 4 which illuminates an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a module separate from the rest of the illumination system. In this case, the illumination system does not include the light source 3.

[0033] A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 is displaceable, in particular in the scanning direction, by a reticle displacement drive 9.

[0034] For illustrative purposes, a Cartesian xyz coordinate system is shown in Figure 1. The x direction extends perpendicular to the plane of the drawing. The y direction extends horizontally and the z direction extends vertically. In Figure 1, the scanning direction extends along the y direction. The z direction extends perpendicular to the object plane 6.

[0035] The projection exposure apparatus 1 comprises a projection optical unit 10. The projection optical unit 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 extends 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.

[0036] The structures on the reticle 7 are imaged onto a photosensitive layer of a wafer 13 arranged in the region of the image field 11 of the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 is displaceable, in particular along the y direction, by a wafer displacement drive 15. The displacement of the reticle 7 by the reticle displacement drive 9 on the one hand and the displacement of the wafer 13 by the wafer displacement drive 15 on the other hand can be performed synchronously with respect to one another.

[0037] The radiation source 3 is an EUV radiation source. The radiation source 3 in particular emits EUV radiation 16, also referred to in the following as working radiation, illumination radiation or illumination light. In particular, the working radiation has a wavelength in the range of 5 nm to 30 nm. The radiation source 3 can be a plasma source, for example an LPP (Laser Produced Plasma) source or a GDPP (Gas Discharge Plasma) source. It can also be a synchrotron-based radiation source. The radiation source 3 can be a Free Electron Laser (FEL).

[0038] Illumination radiation 16 leaving radiation source 3 is focused by collector 17. Collector 17 may be a collector with one or more ellipsoidal and / or hyperbolic reflective surfaces. Illumination radiation 16 may be incident on at least one reflective surface of collector 17 at grazing incidence (GI), i.e. at an angle of incidence greater than 45°, or at normal incidence (NI), i.e. at an angle of incidence smaller than 45°. Collector 17 may be structured and / or coated firstly to optimize its reflectivity for the radiation used and secondly to suppress extraneous light.

[0039] Downstream of the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 may represent the separation between the source module comprising the radiation source 3 and the collector 17 and the illumination optics unit 4.

[0040] The illumination optical unit 4 comprises a deflection mirror 19 and a first facet mirror 20 arranged downstream thereof in the beam path. The deflection mirror 19 can be a plane deflection mirror or a mirror with a beam-influencing effect beyond a pure deflection effect. Alternatively or additionally, the deflection mirror 19 can be in the form of a spectral filter that separates the used optical wavelength of the illumination radiation 16 from extraneous light of wavelengths deviating therefrom. If the first facet mirror 20 is arranged in a plane of the illumination optical unit 4 that is optically conjugate with the object plane 6 as a 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, also referred to as field facets in the following. FIG. 1 shows only some of these facets 21 by way of example.

[0041] The first facet 21 may be in the form of a macroscopic facet, in particular a rectangular facet, or a facet having an arcuate or part-circular peripheral contour. The first facet 21 may be in the form of a planar facet or a convexly or concavely curved facet.

[0042] The first facet 21 itself can also consist of a number of individual mirrors, in particular a number of micromirrors, as is known, for example, from DE 10 2008 009 600. The first facet mirror 20 can in particular be formed as a microelectromechanical system (MEMS system). See DE 10 2008 009 600 for further details.

[0043] Between the collector 17 and the deflection mirror 19, the illumination radiation 16 travels horizontally, ie along the y direction.

[0044] A second facet mirror 22 is arranged downstream of the first facet mirror 20 in the beam path of the illumination optical unit 4. If the second facet mirror 22 is arranged in the pupil plane of the illumination optical unit 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged away from the pupil plane of the illumination optical unit 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 Patent Application Publication No. 2006 / 0132747, EP 1 614 008 and US 6,573,978.

[0045] The second facet mirror 22 includes 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.

[0046] The second facet 23 may likewise be a macroscopic facet, which may have, for example, a circular, rectangular or hexagonal perimeter, or a facet made up of a micromirror. In this respect, reference is also made to DE 10 2008 009 600 A1.

[0047] The second facet 23 may have a flat reflective surface or a convexly or concavely curved reflective surface.

[0048] The illumination optical unit 4 results in a double-faceted system, this basic principle also being called a fly's eye condenser (fly's eye integrator).

[0049] It may be advantageous not to arrange the second facet mirror 22 exactly in a plane that is optically conjugate with the pupil plane of the projection optical unit 10. In particular, as described in DE 10 2017 220 586 A1, the pupil facet mirror 22 may be arranged so that it is tilted with respect to the pupil plane of the projection optical unit 10.

[0050] The individual first facets 21 are imaged into the object field 5 by means of a second facet mirror 22. The second facet mirror 22 is the last beam-shaping mirror in the beam path upstream of the object field 5 or indeed the final mirror for the illumination radiation 16.

[0051] In yet another embodiment (not shown) of the illumination optical unit 4, a transfer optical unit, which in particular contributes to the imaging of the first facet 21 into the object field 5, can be arranged in the beam path between the second facet mirror 22 and the object field 5. The transfer optical unit can have exactly one mirror or two or more mirrors arranged one behind the other in the beam path of the illumination optical unit 4. The transfer optical unit can in particular include one or two normal incidence mirrors (NI mirrors) and / or one or two grazing incidence mirrors (GI mirrors).

[0052] In the embodiment shown in FIG. 1, the illumination optical unit 4 comprises exactly three mirrors downstream of the collector 17 , in particular a deflection mirror 19 , a field facet mirror 20 and a pupil facet mirror 22 .

[0053] In yet another embodiment of the illumination optical unit 4, the deflection mirror 19 is not required, so that the illumination optical unit 4 can then have exactly two mirrors downstream of the collector 17, specifically a first facet mirror 20 and a second facet mirror 22.

[0054] The imaging of the first facet 21 onto the object plane 6 by the second facet 23 or by means of the second facet 23 and the transfer optical unit is usually only an approximate imaging.

[0055] The projection optical unit 10 comprises a number of mirrors Mi, which are numbered according to their position in the beam path of the projection exposure apparatus 1 .

[0056] 1, the projection optical unit 10 includes six mirrors M1 to M6. 4, 8, 10, 12 or any other number of mirrors Mi are equally possible. The penultimate mirror M5 and the final mirror M6 each have a passage aperture for the illumination radiation 16. The projection optical unit 10 is a double-shielded optical unit. The projection optical unit 10 has an image-side numerical aperture that is greater than 0.5, may be greater than 0.6, and may be, for example, 0.7 or 0.75.

[0057] The reflective surface of the mirror Mi can be embodied as a freeform surface without an axis of rotational symmetry. Alternatively, the reflective surface of the mirror Mi can be designed as an aspheric surface, in which the reflective surface shape has exactly one axis of rotational symmetry. Like the mirrors of the illumination optical unit 4, the mirror Mi can have a coating that is highly reflective with respect to the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0058] Projection optical unit 10 has a large object-image offset in the y direction between the y coordinate of the center of object field 5 and the y coordinate of the center of image field 11. In the y direction, this object-image offset may be approximately the same size as the z distance between object plane 6 and image plane 12.

[0059] In particular, the projection optical unit 10 can have an anamorphic form. In particular, it has different imaging scales βx, βy in the x and y directions. The two imaging scales βx, βy of the projection optical unit 10 are preferably (βx, βy)=(+ / -0.25, + / -0.125). A positive imaging scale β means imaging without image inversion. A negative sign of the imaging scale β means imaging with image inversion.

[0060] The projection optical unit 10 results in a size reduction in the x-direction, ie perpendicular to the scanning direction, by a ratio of 4:1.

[0061] The projection optical unit 10 provides a size reduction of 8:1 in the y-direction, ie the scan direction.

[0062] Other imaging scales are possible as well, including imaging scales of the same sign and magnitude in the x and y directions, for example 0.125 or 0.25.

[0063] The number of intermediate image planes in the x and y directions in the beam path between the object field 5 and the image field 11 may be the same or may differ depending on the embodiment of the projection optical unit 10. An example of a projection optical unit 10 with a different number of such intermediate images in the x and y directions is known from US Patent Application Publication No. 2018 / 0074303.

[0064] Each pupil facet 23 is assigned to exactly one of the field facets 21 in order to form a respective illumination channel that illuminates the object field 5. In particular, this makes it possible to obtain illumination according to the Köhler principle. The far field is decomposed into a plurality of object fields 5 by means of the field facets 21. The field facets 21 generate a plurality of images of intermediate foci on the respectively assigned pupil facets 23.

[0065] By means of the respectively assigned pupil facets 23, the field facets 21 are imaged onto the reticle 7 in an overlapping manner in order to illuminate the object field 5. The illumination of the object field 5 is in particular as uniform as possible. Its uniformity error is preferably less than 2%. By overlapping the different illumination channels, field uniformity can be obtained.

[0066] The illumination of the entrance pupil of the projection optical unit 10 can be geometrically defined by the arrangement of the pupil facets. By selecting the illumination channels, and in particular the subset of pupil facets, that direct light, the intensity distribution at the entrance pupil of the projection optical unit 10 can be set. This intensity distribution is also referred to as the illumination setting.

[0067] A similarly favorable pupil uniformity in the region of a defined illuminated portion of the illumination pupil of the illumination optical unit 4 can be achieved by redistribution of the illumination channels.

[0068] Further aspects and details of the illumination of the object field 5, in particular the entrance pupil of the projection optical unit 10, are explained below.

[0069] In particular, the projection optical unit 10 may have a concentric entrance pupil, which may be accessible, or which may be inaccessible.

[0070] The entrance pupil of the projection optical unit 10 cannot usually be illuminated exactly using the pupil facet mirror 22. In the case of imaging with a projection optical unit 10 that telecentrically images the center of the pupil facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, it is possible to find a surface where the distance determined for the pair of aperture rays is minimal. This surface represents the entrance pupil or a real space surface conjugate to it. In particular, this surface has a finite curvature.

[0071] The projection optical unit 10 may have different entrance pupil positions for the tangential and sagittal beam paths. In this case, an imaging element, in particular an optical component part of the transfer optical unit, should be provided between the second facet mirror 22 and the reticle 7. This optical element can be used to take into account the different positions of the tangential and sagittal entrance pupils.

[0072] In the arrangement of the components of the illumination optical unit 4 shown in Figure 1, the pupil facet mirror 22 is arranged in a plane conjugate with the entrance pupil of the projection optical unit 10. The field facet mirror 20 is arranged so as to be inclined with respect to the object plane 6. The first facet mirror 20 is arranged so as to be inclined with respect to the arrangement plane defined by the deflection mirror 19.

[0073] The first facet mirror 20 is disposed so as to be inclined with respect to the disposition plane defined by the second facet mirror 22 .

[0074] FIG. 2 shows diagrammatically in meridian section yet another projection exposure apparatus 101 for DUV projection lithography in which the invention can also be used.

[0075] The construction and imaging principle of the projection exposure apparatus 101 are identical to those described in connection with Figure 1. Identical component parts are designated by reference numerals which are increased by 100 compared to Figure 1, i.e. the reference numerals in Figure 2 start with 101.

[0076] 1, the DUV radiation 116 used as the light has a large wavelength in the range of 100 nm to 300 nm, in particular 193 nm, so that refractive, diffractive and / or reflective optical elements 117, such as lens elements, mirrors, prisms, end plates, etc., can be used for imaging or illumination in the DUV projection exposure apparatus 101. The projection exposure apparatus 101 essentially comprises in this case an illumination system 102, a reticle holder 108 for accommodating and accurately positioning a reticle 107 provided with structures that determine the subsequent structure on a wafer 113, a wafer holder 114 for holding, moving and accurately positioning said wafer 113, and a projection lens 110 with a number of optical elements 117, which are held by mounts 118 in a lens housing 119 of the projection lens 110.

[0077] Illumination system 102 provides the DUV radiation 116 required for imaging reticle 107 onto wafer 113. A laser, plasma source, etc. can be used as the source of this radiation 116. The radiation 116 is shaped by optics in illumination system 102 so that upon incidence on reticle 107, the DUV radiation 116 has desired properties with respect to diameter, polarization, wavefront shape, etc.

[0078] Besides the additional use of refractive optical elements 117 such as lens elements, prisms, end plates, etc., the configuration of the downstream projection optical unit 110 with the lens housing 119 does not differ in principle from the configuration described in FIG. 1 and therefore will not be described in further detail.

[0079] FIG. 3a shows a component 30 known from the prior art, including a mirror 31 and two actuators in the form of actuator matrices 32. The actuator matrices 32 are arranged side by side behind the mirror 31, located opposite the optically active surface (not shown) of the mirror 31. Each actuator matrix 32 has a plurality of square actuator pads 33 arranged in rows and columns, with holes at the corners for connecting the actuator pads 33 to a controller (not shown). The plate-shaped actuator matrix 32 is rectangular, with two of its four peripheries extending in the scanning direction indicated by the thick arrow in FIG. 3a. The holes 34 between the actuator pads 33 are positioned front to back, respectively, on an axis (indicated by a dashed line) extending parallel to the scanning direction. The resulting parasitic deformations accumulate in the scanning direction, causing aberrations. In principle, the actuator matrix 32 can also have a curved shape. The number of actuator matrices 32 arranged on the mirror 31 can be freely selected; i.e., three, four, or more actuator matrices 32 can be formed on the mirror 31. Likewise, the number of rows and columns of the actuator matrices 32 can be freely selected. Thus, in addition to the embodiment described in Fig. 3a with two actuator matrices 32 with 4 rows and 3 columns, the component 30 can also include three actuator matrices 32 with 5 rows and 5 columns, or four matrices 32 with 4 rows and 5 columns, or any other combination on the mirror 31. The number of actuator matrices 32 and rows and columns here depends mainly on the application and productivity of the actuator matrices 32.

[0080] Figure 3b shows a diagram of the parasitic aberrations that accumulate with the scanning motion. These are caused by parasitic deformations due to edge effects of the actuator matrix 32 due to stiffness losses. The point densities used in the diagram correspond here to wavefront deviations in the positive or negative direction. Aberrations aligned with the scanning direction, indicated by the thick arrows in Figure 3b, are clearly visible in the form of regions of identical point density that extend in the scanning direction.

[0081] FIG. 4a shows a component 30 according to the present invention, including a mirror 31 and two actuators in the form of actuator matrices 35 arranged side by side. Each actuator matrix 35 has hexagonal actuator pads 36, which also have holes 38 at the corners for connecting the actuator pads 36 to a controller (not shown). The holes 38 are elliptical, with their major axes aligned perpendicular to the scanning direction. The actuator pads 36 are arranged in rows 37 perpendicular to the scanning direction, as indicated by the thick arrows in FIG. 4a. The rows 37 are also arranged perpendicular to the scanning direction, alternately offset from each other by half the width of an actuator pad. This results in a peripheral contour that snakes around the actuator matrices 35 positioned parallel to the scanning direction. Therefore, parasitic deformations induced in the peripheral contour due to stiffness losses are advantageously averaged out by the scanning motion, minimizing the resulting aberrations. In addition to the adaptation of the peripheral contour to the scanning direction, the minor axis of the contact elliptical holes 38 of the actuator pads 36 is smaller than the diameter of the holes shown in FIG. 3a, thereby reducing the cumulative length of the edge portions of the holes 38 extending parallel to the scanning direction. Furthermore, the multiple axial holes 38, shown by the dotted-dashed lines in FIG. 4a, are arranged parallel to the scanning direction due to the hexagonal shape of the actuator pads 36, thereby reducing the cumulative parasitic error per axis. As a result, the amplitude of the aberrations is advantageously minimized. To minimize the distance between adjacent actuator matrices 35, the actuator matrices 35 are arranged interdigitated. Therefore, the deformation effect of the actuator pads 36 at the abutting edges of two adjacent actuator matrices 35 is comparable to that of the actuator matrix 32 described in FIG. 3a, which is known from the prior art. As already explained with reference to FIG. 3a, the actuator matrix 32 can, in principle, also have a curved shape. Furthermore, the number of actuator matrices 32 arranged on the mirror 31 can be freely selected, i.e., three, four or more actuator matrices 32 can be formed on the mirror 31. Similarly, the number of rows and columns of the actuator matrices 32 can also be freely selected.4a with two actuator matrices 32 with 4 rows and 3 columns, the component 30 can also include three actuator matrices 32 with 5 rows and 5 columns, or four matrices 32 with 4 rows and 5 columns, or any other combination on the mirror 31. The number of actuator matrices 32 and rows and columns here depends mainly on the application and productivity of the actuator matrices 32.

[0082] Compared to the parasitic aberration diagram described in Figure 3b, Figure 4b shows a significant reduction in the parasitic aberrations accumulated by the scanning operation, which can be recognized firstly by a reduction in the average absolute value of the point density and secondly by a deviation from the scanning direction of the profiles of areas of the same point density and therefore of the same aberrations.

[0083] 5a-5f show further alternative embodiments of actuator matrices 39.1, 39.2, 39.3, 39.4, 39.5, 39.6, which differ in the geometry of the actuator pads 40.1, 40.2, 40.3, 40.4, 40.5, 40.6 and in the arrangement of the contact holes 41.1, 41.2, 41.3, 41.4, 41.5, 41.6. The different combinations of geometry of the actuator pads 40.1, 40.2, 40.3, 40.4, 40.5, 40.6 and the shape and arrangement of the holes 41.1, 41.2, 41.3, 41.4, 41.5, 41.6 are shown in the table below. The scanning direction is indicated by the arrows.

[0084] [Table 1]

[0085] Figure 6 shows yet another embodiment of the invention, showing a component 30 comprising a mirror 31 and an actuator matrix 43. As already mentioned above, parasitic deformations caused by stiffness losses in the peripheral region of the actuator matrix 43 are minimized by the scanning action if the perimeter of the actuator matrix 43 is minimized on an axis aligned parallel to the scanning direction. In the exemplary embodiment shown in Figure 6, by making the actuator matrix 43 trapezoidal, the entire perimeter is not aligned parallel to the scanning direction, so that parasitic aberrations caused by parasitic deformations in the peripheral region can advantageously be almost completely avoided or can be largely averaged out by the scanning action.

[0086] 7 shows a detailed view of the component 30, which comprises a mirror 31 and actuator pads 51 arranged around the periphery of the actuator embodied in the form of an actuator matrix 50. The actuator pads 51 are divided into partial actuator pads 52 and peripheral actuator pads 53, which are controllable independently of one another via respective lines 54, 55. This has the advantage that the deformation of the optically active surface 56 caused by the peripheral actuator pads 53, shown in solid lines in FIG. 7, is greater in the peripheral region than the deformation caused by the undivided actuator pads, shown in dashed lines in FIG. 7. Advantageously, parasitic deformations caused by stiffness losses in the peripheral region of the actuator matrix 50 are thereby at least partially compensated for, so that parasitic aberrations are minimized.

[0087] Figure 8 shows a possible way of designing a component 30 of a projection exposure apparatus 1, 101 in order to minimize the effect on the imaging quality of a projection exposure apparatus 1, 101 having an optical element 31 and actuators 32, 35, 39.x, 43, 50 of parasitic deformations caused by deformations of the optical element 31 by the actuators 32, 35, 39.x, 43, 50.

[0088] In a first method step 61, the actuators 32, 35, 39.x, 43, 50 are designed.

[0089] In a second method step 62, the parasitic deformations of the optical element 31 caused by actuation or by differences in the thermal expansion coefficients of the optical element 31 and the actuators 32, 35, 39.x, 43, 50 are determined.

[0090] In a third method step 63, the parasitic aberrations are determined on the basis of the parasitic deformations, taking into account the summation effect of the scanning exposure used in the projection exposure apparatus.

[0091] In a fourth method step 64, the actuator is optimized based on the determined parasitic aberrations, whereby in particular the shape and arrangement of the individual actuator pads and holes can be varied.

[0092] In a fifth step 65, at least some of the previous process steps are repeated until the value of the parasitic aberrations is below a predetermined value. [Explanation of symbols]

[0093] 1. Projection exposure equipment 2. Lighting system 3 Radiation source 4. Illumination optical unit 5 Object field of view 6 Object plane 7 Reticle 8 Reticle Holder 9 Reticle Displacement Drive 10 Projection optical unit 11 Image field 12 Image plane 13 wafers 14 wafer holder 15 Wafer Displacement Drive 16 EUV radiation 18 Intermediate focal plane 19 Deformable Mirror 20 Faceted Mirror 21 Facets 22 Faceted Mirror 23 Facets 30 Components 31 Mirror 32 Actuator Matrix 33 Actuator Pad 34 holes 35 Actuator Matrix 36 Actuator Pad 37 rows 38 holes 39.1~39.6 Actuator matrix 40.1~40.6 Actuator pad 41.1~41.6 hole 42 electrodes 43 Actuator Matrix 50 Actuator Matrix 51 Actuator Pad 52 Partial Actuator Pad 53 Peripheral Actuator Pad 54 lines 55 lines 56 Optically Effective Surface 61 Method Step 1 62 Method Step 2 63 Method Step 3 64 Method Step 4 65 Method Step 5 101 Projection exposure equipment 102 Lighting System 107 Reticle 108 Reticle Holder 110 Projection optical unit 113 wafers 114 Wafer holder 116 DUV radiation 117 Optical Elements 118 Mount 119 Lens Housing

Claims

1. 1. A projection exposure apparatus (1, 101) with a projection objective (10, 110) including a component (30), the component (30) including an optical element (31) and an actuator (32, 35, 39.x, 43, 50), the optical element (31) and the actuator (32, 35, 39.x, 43, 50) being connected together in a force-fixed manner, the actuator (32, 35, 39.x, 43, 50) being configured to at least locally deform the optical element (31), 1. A projection exposure apparatus, characterized in that the actuators (32, 35, 39.x, 43, 50) are embodied in such a way as to minimize the effect on imaging quality of stiffness losses in the periphery defining the actuators (32, 35, 39.x, 43, 50).

2. 2. A projection exposure apparatus (1, 101) according to claim 1, 1. A projection exposure apparatus, characterized in that the actuator is in the form of an actuator matrix (32, 35, 39.x, 43, 50) comprising at least two actuator pads (33, 36, 40.x, 51).

3. 3. A projection exposure apparatus (1, 101) according to claim 1 or 2, 1. A projection exposure apparatus (1, 101) characterized in that the cumulative length of the periphery of the actuator (32, 35, 39.x, 43, 50) extending on an axis parallel to a scanning direction used in the projection exposure apparatus (1, 101) is minimized.

4. 4. A projection exposure apparatus (1, 101) according to claim 3, 10. A projection exposure apparatus, characterized in that the outer periphery of the actuator (35, 39.x, 43, 50) is oriented at least partially obliquely with respect to the scanning direction.

5. 5. A projection exposure apparatus (1, 101) according to claim 3 or 4, A projection exposure apparatus, characterized in that the actuator (35) comprises a peripheral contour that is serpentine relative to the scanning direction.

6. 5. A projection exposure apparatus (1, 101) according to claim 3 or 4, A projection exposure apparatus, characterized in that the linear peripheral structure of the actuator (43) is oriented obliquely with respect to the scanning direction.

7. A projection exposure apparatus (1, 101) according to any one of claims 2 to 6, 1. A projection exposure apparatus (1, 101) comprising: contact holes (34, 38, 41.x) of the actuator pads (33, 36, 40.x, 51) formed in the actuator matrix (32, 35, 39.x, 43, 50) designed to reduce the cumulative length of the edge portions of the holes (34, 38, 41.x) extending on an axis parallel to a scanning direction used in the projection exposure apparatus (1, 101).

8. 8. A projection exposure apparatus (1, 101) according to claim 7, A projection exposure apparatus, characterized in that the area of ​​at least some of said holes (34, 38, 41.x) is minimized.

9. 9. A projection exposure apparatus (1, 101) according to claim 7 or 8, 10. A projection exposure apparatus, comprising: a projection exposure system in which the holes (34, 38, 41.x) are arranged in such a way as to reduce the number of holes (34, 38, 41.x) arranged on an axis extending parallel to the scanning direction.

10. A projection exposure apparatus (1, 101) according to any one of claims 2 to 9, Projection exposure apparatus, characterized in that the actuator pads (33, 36, 40.x, 51) have a triangular, rectangular or hexagonal geometric shape.

11. A projection exposure apparatus (1, 101) according to any one of claims 1 to 10, 10. A projection exposure apparatus, characterized in that the actuator (50) has a separately controllable part (53) for compensating for stiffness losses.

12. 12. A projection exposure apparatus (1, 101) according to claim 11, 1. A projection exposure apparatus, comprising: a projection exposure device, the projection exposure device including: a projection exposure device configured to correct parasitic deformations caused by stiffness losses, the projection exposure device being configured as peripheral actuator pads (53) of the actuator pads (51) arranged in a peripheral region of the actuator matrix (50), the peripheral actuator pads (53) being controllable independently of a second region of the actuator pads (51) formed as partial actuator pads (54).

13. 1. A method for designing a component (30) of a projection exposure apparatus (1, 101) having an optical element (31) and an actuator (32, 35, 39.x, 43, 50) in order to minimize the effect of parasitic deformations on the imaging quality of the projection exposure apparatus (1, 101) when deformations of the optical element (31) are caused by the actuator (32, 35, 39.x, 43, 50), comprising: designing the actuators (32, 35, 39.x, 43, 50); determining the parasitic deformation of the optical element (31) caused by actuation or by differences in the thermal expansion coefficients of the optical element (31) and the actuators (32, 35, 39.x, 43, 50); determining parasitic aberrations based on parasitic deformations, taking into account the summation effect of scanning exposures used in the projection exposure system (1, 101); optimizing the actuators (32, 35, 39.x, 43, 50) based on the determined parasitic aberrations; repeating at least some of the previous process steps (61, 62, 63, 64) until the value of the parasitic aberrations falls below a predetermined value; A method comprising:

14. 14. The method of claim 13, A method comprising: correcting for parasitic deformations using at least a portion of the movement of said actuators (32, 35, 39.x, 43, 50).

15. 15. The method of claim 13 or 14, 10. A method according to claim 9, further comprising taking into account further measures for optimizing the imaging quality present in the projection exposure apparatus (1, 101) when determining the parasitic aberrations.

16. 16. The method of claim 15, 10. A method according to claim 9, wherein said means are embodied in the form of a manipulator for positioning or deforming further optical elements of said projection exposure apparatus (1, 101).

17. 17. The method of claim 15 or 16, 1. A method characterized in that it embodies a means in the form of a simulation-based algorithm for predicting the imaging quality taking into account a number of influencing parameters and for determining the manipulator movements required therefor.

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