Method for producing a mirror assembly, and coating system

Abstract

The invention relates to a method for producing a mirror assembly, as well as a coating system. The mirror assembly can be, in particular, a mirror assembly for microlithography, e.g. for a microlithographic projection exposure system. In a method according to the invention, in a coating process of a plurality of mirror substrates (106, 206, 306, 406) carried out in a coating system, coating material is supplied by at least one target (103, 203, 303, 403, 503) for the deposition of at least one respective layer system on each of the mirror substrates (106, 206, 306, 406), wherein the mirror substrates (106, 206, 306, 406) are each tilted by a tilt angle that can be individually adjusted for each mirror substrate in order to individually adjust the respective thickness profile generated in the coating process.

Description

[0001] Method for producing a mirror arrangement, and coating system

[0002] This application claims priority from German patent application DE 10 2023 200 603.0, filed on January 26, 2023. The content of this DE application is incorporated by reference into the present application text.

[0003] BACKGROUND OF THE INVENTION

[0004] Field of the invention

[0005] The invention relates to a method for producing a mirror arrangement, as well as to a coating system. The mirror arrangement can, in particular, be a mirror arrangement for microlithography, e.g., for a microlithographic projection exposure system.

[0006] State of the art

[0007] Microlithography is used to manufacture microstructured components, such as integrated circuits or LCDs. The microlithography process is carried out in a so-called projection exposure system, which has an illumination device and a projection lens. The image of a mask (= reticle) illuminated by the illumination device is projected by the projection lens onto a substrate (e.g., a silicon wafer) coated with a light-sensitive layer (photoresist) and arranged in the image plane of the projection lens, in order to transfer the mask structure to the light-sensitive coating of the substrate.

[0008] In projection lenses designed for the EUV range, e.g. at wavelengths of about 13 nm or about 7 nm, mirrors are used as optical components for the imaging process due to the lack of availability of suitable light-transmitting refractive materials.

[0009] In the illumination system of a microlithographic projection exposure system designed for operation in the EUV range, but also in microlithographic projection exposure systems designed for operation at wavelengths in the DUV range (e.g., at wavelengths of approximately 248 nm or approximately 193 nm), the use of mirror arrangements composed of a plurality of individual mirrors (e.g., in the form of facet mirrors or pupil facet mirrors) for the flexible adjustment of different illumination angle distributions is known. These individual mirrors can each be independently adjustable or tiltable via solid-state joints and can themselves be constructed as blocks of individual micromirrors in the form of microelectromechanical systems (so-called "MEMS mirrors").

[0010] Magnetron coating systems, for example, are used for mirror production. Such a magnetron coating system typically has a plurality of magnetrons, each of which is assigned a target with a corresponding coating material. To coat a substrate, the respective substrate (this refers to the carrier for the layer or layer system to be applied in the coating process) is then guided over the coating positions facing the respective targets or magnetrons.

[0011] A problem that occurs in practice is that coating errors, particularly in the form of layer thickness errors or due to alignment errors in the respective coating holder, are generally unavoidable in the actual coating process. Undesirable drift (i.e., a temporal change in the layer thicknesses set during the coating process, both within a layer structure and across multiple, successively manufactured mirrors) can also occur. These problems are particularly serious for EUV mirrors with periodically constructed multi-layer systems because the respective layer thickness errors are systematically propagated in the layer thickness profile, with the result that even small deviations of the individual layers from the respective target layer thickness lead to significant impairments in the overall performance of the optical system.

[0012] In addition to the need to correct the effects mentioned above, there is also a need in practice to improve the reflectivity and ultimately the overall performance of the optical system through flexible, targeted selection of the layer properties.

[0013] With regard to the prior art, reference is made merely by way of example to DE 10 2016 201 564 A1, DE 10 2015 225 535 A1, DE 10 2015 217 603 A1, DE 10 2015 217 603 A1, DE 10 2012 215 359 A1, DE 10 2012 204 833 A1, WO 2022 / 008102 A1 and US 10,423,073 B2.

[0014] SUMMARY OF THE INVENTION

[0015] Against the above background, it is an object of the present invention to provide a method for producing a mirror arrangement and a coating system so that a flexible manipulation of layer properties is possible, e.g. for correcting layer thickness errors and / or alignment errors.

[0016] This problem is solved by the features of the independent patent claims.

[0017] In a method according to the invention for producing a mirror arrangement with a plurality of mirror elements, in particular for microlithography, coating material is supplied from at least one target to a plurality of mirror substrates in a coating process carried out in a coating system for deposition of a layer system on each of the mirror substrates.

[0018] The method is characterized in that the mirror substrates are tilted by a tilt angle that can be individually adjusted for each mirror substrate in order to individually adjust the thickness profile generated during the coating process. This tilting of the mirror substrates during the coating process or in the coating system can, in particular, be carried out "in situ."

[0019] For the purposes of the present application, a thickness profile is understood to be the lateral thickness profile of a layer or layer system. The thickness profile can generally be a constant thickness profile or one that varies across the optical effective surface of the mirror element. The layer system can, in particular, contain a reflective layer system and, if necessary, also other functional layers.

[0020] The wording that the mirror elements are "each tilted by a tilt angle that can be individually adjusted for each mirror substrate" is to be understood in the context of the present application to encompass both embodiments in which several or all mirror elements are each tilted by the same tilt angle and embodiments in which several or all mirror elements are tilted by mutually different tilt angles. Furthermore, the tilt angles set for the individual mirrors can be temporally variable or constant, depending on the embodiment. Furthermore, the tilt angle set for one or more mirror elements can have a value other than zero or even the value zero.

[0021] The invention is based on the idea that by changing the deposition angle or vapor deposition angle during the coating process, the layer thickness profile and also other layer properties (such as roughness, crystallinity, layer stress, etc.) can be influenced. In particular, the invention includes the principle of controlled modification of these properties by tilting the respective mirror substrates. In the event of a potential deterioration of certain parameters or layer properties, countermeasures can be taken by adjusting other process conditions (known as such). For example, if a comparatively strong tilt in a certain system leads to an undesirable increase in roughness, this can be influenced or reduced by optimizing, for example, the working pressure.

[0022] The invention is based in particular on the concept of individually adjusting a tilt angle for each of the mirror substrates during the manufacture of a mirror arrangement having a plurality of mirror elements before or during the deposition of the respective layer systems on the individual mirror substrates by actively controlling the individual mirror substrates during the coating process. This allows the respective thickness profile, and possibly also other layer properties, to be specifically influenced via the change in the vapor deposition angle (and thus in turn the amount of coating material deposited on the mirror substrate) associated with this tilt. By individually adjusting a tilt angle for each of the mirror substrates, an individual thickness factor for the coating process can be assigned to each mirror substrate to be coated or to each manufactured mirror element.

[0023] The respective tilt of the individual mirror substrates can also be varied dynamically during the coating process, whereby, in particular, thickness profiles can also be generated in which variations in the layer thickness or, if applicable, other layer properties are present even within one and the same mirror element (and not only at the respective boundaries of adjacent mirror elements). In other words, according to the invention, mirror arrangements can also be produced in which the respective boundaries between regions with different layer properties do not correspond to the boundaries between adjacent mirror elements.

[0024] The invention differs with the above-described flexible and individual tilting of individual mirror substrates in particular from conventional approaches in which only a specific tilt angle is statically set for different blocks of mirror substrates in groups before they are introduced into the process chamber and then the coating process is carried out after the respective blocks have been introduced into the process chamber in order to finally assemble the corresponding blocks to form the mirror arrangement.

[0025] According to the invention, particular flexibility is also achieved with regard to the design of the mirror arrangement in that the individual tilting of a mirror substrate, on the one hand, sets a changed vapor deposition angle (and thus a different average thickness factor during coating compared to a respective adjacent mirror substrate), but on the other hand, also changes the layer thickness profile generated in the coating process across the respective mirror substrate itself. Depending on the specific application scenario, the latter effect (i.e., a locally varying layer thickness profile) may also be desirable or used to compensate for undesired effects or aberrations in the respective optical system.

[0026] According to one embodiment, the tilting is carried out in such a way that a systematic coating error of the coating system is at least partially corrected via the thickness profiles generated for the plurality of mirror substrates.

[0027] According to one embodiment, the tilting is performed in such a way that an alignment error of the mirror substrates in the coating system is at least partially corrected via the thickness profiles generated for the plurality of mirror substrates. According to one embodiment, different thickness profiles are generated for the plurality of mirror substrates.

[0028] According to one embodiment, the tilting is carried out in such a way that constant thickness profiles are generated for the individual mirror substrates.

[0029] According to one embodiment, by changing an average deposition angle in the coating process, at least one further layer property, in particular roughness, crystallinity or layer stress, is varied in addition to the layer thickness profile.

[0030] According to one embodiment, the mirror substrates are moved along a predetermined movement path relative to the target in the coating process.

[0031] According to one embodiment, the tilt of the individual mirror substrates is varied during a single pass of the movement path.

[0032] According to one embodiment, this variation is carried out in such a way that the respective mirror substrate is tilted towards the target during the entire passage of the movement path or is tilted away from the target during the entire passage of the movement path.

[0033] According to one embodiment, the mirror substrates are rotated during the coating process, wherein the tilting occurs depending on the respective angle of rotation of this rotation.

[0034] According to one embodiment, the tilting occurs in such a way that gaps between adjacent mirror substrates are at least partially shaded as a result of the tilting during the coating process. According to one embodiment, the coating material is supplied from the at least one target at a time-varying rate. In particular, in a scenario in which shadowing of gaps between adjacent mirror substrates is not successful depending on the rotational position of the coating holder, the supply rate of coating material ("sputtering rate") can be reduced to avoid contamination of mechanical components located behind the gaps by coating material.

[0035] In embodiments, the movement path of the coating holder can also be designed such that the mirror substrates are not located vertically above the target at any time during the coating process.

[0036] Furthermore, in embodiments, a rotational movement may also occur, if appropriate, only around a single (spin) rotation axis.

[0037] Furthermore, in embodiments of the invention, the effect of the inventive tilting of the mirror substrates in the coating process can also be enhanced by utilizing a radial dependence of the deposited layer thickness. In this case, the fact that the amount of deposited coating material also depends on the position of the mirror substrate on the coating holder can be exploited. With comparatively large holding radii (i.e. a position on the coating holder that is further radially outwards), the substrate passes over the material source at the edge, where the distribution of layer-forming particles is inhomogeneous. In this position, comparatively more coating material comes from the center of the target than from the edge of the target. By tilting the substrate towards the center of the target, the angle of incidence of the stronger particle stream is favored, while that of the weaker particle stream becomes less favorable (and vice versa).As a result, the angular dependence of the layer thickness resulting from the coating process—i.e., the "layer thickness variation" realized in the coating process according to the invention—is further amplified by a few percent relative to the layer thickness. According to one embodiment, the mirror arrangement is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm.

[0038] The invention further relates to a mirror arrangement, in particular for microlithography, which is produced by a method having the features described above.

[0039] The invention further relates to a coating system for producing a mirror arrangement, in particular for microlithography, with a process chamber, wherein the following are arranged in this process chamber:

[0040] - at least one target for providing coating material;

[0041] - a coating holder for holding a plurality of mirror substrates;

[0042] - a first drive unit for performing a translational movement of the coating holder;

[0043] - a second drive unit for performing a rotational movement of the coating holder; and

[0044] - a third drive unit for individually adjustable tilting of the mirror substrates during the coating process.

[0045] The invention further relates to a microlithographic projection exposure apparatus having an illumination device and a projection objective, wherein the illumination device illuminates a mask located in an object plane of the projection objective during operation of the projection exposure apparatus, and the projection objective images structures on this mask onto a light-sensitive layer located in an image plane of the projection objective, wherein the projection exposure apparatus has at least one mirror arrangement which is produced by a method having the features described above.

[0046] Further embodiments of the invention can be found in the description and the dependent claims. The invention is explained in more detail below with reference to exemplary embodiments illustrated in the accompanying drawings.

[0047] BRIEF DESCRIPTION OF THE DRAWINGS

[0048] They show:

[0049] Figure 1 is a schematic representation of a possible basic structure of a coating system according to the invention;

[0050] Figures 2a-5b are schematic representations for explaining exemplary embodiments of a method according to the invention; and

[0051] Figure 6 is a schematic representation of a system for operation in

[0052] EUV designed projection exposure system.

[0053] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0054] Fig. 1 initially shows a schematic representation of a basic possible structure of a coating system 100 according to the invention. In this case, a coating holder 102 for holding a plurality of mirror substrates 106 and at least one target 103 for providing coating material are arranged in a process chamber 101 (to which a vacuum pump (not shown) is connected). As indicated in Fig. 1 (but without the invention being limited thereto), several mirror substrates 106 or the ultimately manufactured mirror elements can be grouped into individual blocks 105. To deposit a layer system on each of the mirror substrates, the coating holder 102 carrying the mirror substrates 106 is guided along a predetermined movement path over the at least one target 103.Here, the coating holder 102 performs a translational movement effected by a first drive unit 108 and, if necessary, also a rotational movement effected by a second drive unit 109. In addition to the first and second drive units, the coating system 100 according to the invention has a third drive unit 110 for the individually adjustable tilting of the mirror substrates 106 during the coating process. "107" denotes mechanical components or joints assigned to the mirror substrates 106.

[0055] Furthermore, it is assumed that in order to produce a mirror arrangement (which can be designed for operation in the EUV or also for the DUV wavelength range), a desired thickness profile of the layer structure produced on the respective mirror substrate (including the reflection layer system and any functional layers) is to be produced for each of the individual mirror elements of the mirror arrangement.

[0056] In the following, exemplary embodiments of a method according to the invention are explained schematically with reference to the schematic diagrams of Figs. 2a-5b. These embodiments have in common that mirror substrates are tilted with an individually adjustable tilt angle (or independently of one another) for individually adjusting the thickness profile generated in a coating process (e.g., carried out in the coating system of Fig. 1). An electrical power supply required for tilting can be provided on the coating holder side, and rechargeable batteries can also be used.

[0057] In Fig. 2a-2c, a predetermined movement path of a mirror substrate 206 relative to a target 203 is indicated, wherein "204" denotes the coating material supplied from the target 203 to the mirror substrate 206. The dimensions of the individual mirror substrates 206 can be 1 mm * 1 mm merely by way of example (and without the invention being limited thereto). Fig. 2a illustrates the movement path of the mirror substrate 206 in the non-tilted state, and Fig. 2b illustrates the movement path in the tilted state with a temporally constant tilt angle. Fig. 2c also illustrates the movement path in the tilted state, wherein, according to Fig. 2c, in contrast to Fig. 2b, the tilt of the mirror substrate 206 is varied during a single pass of the movement path.This one-time change in the tilt angle of the mirror substrate 206 can occur, in particular, upon reaching the position centrally above the target 203 and in such a way that the mirror substrate 206 is tilted, on average, toward the target 203. In further embodiments, the change in the tilt angle can also occur in such a way that the mirror substrate 206 is tilted, on average, away from the target 203. In both scenarios, a symmetry breaking that would otherwise occur during the movement of the mirror substrate 206 relative to the target can be avoided, thus achieving a constant thickness profile during the coating of the respective mirror substrate 206.

[0058] In a quantitative analysis, a change in the deposition angle of 100 mrad (corresponding to approximately 6°) caused by the tilting according to the invention, starting from a vertical coating and due to cos(0.1) = 0.995, leads to a variation in the produced layer thickness of approximately 0.5%. Due to the nonlinear relationship via the cosine function, the effect on the produced layer thickness achieved by changing the deposition angle increases significantly at larger deposition angles: A change in the average impact angle of layer-forming particles by 10° already causes a variation in the produced layer thickness of approximately 2.2%, whereas a change in the average impact angle of 30° already leads to a variation in the produced layer thickness of approximately 6.2%.

[0059] In further embodiments, the tilting of the mirror substrates according to the invention can also take into account the fact that the mirror substrates are rotated during the coating process, wherein the tilting can occur in particular as a function of the respective angle of this rotation. The schematic representations in Figs. 3a-3b illustrate said rotational movement in a plan view. By dynamically tilting a mirror substrate 306, it can be achieved that this is always (i.e., in particular over the entire rotational movement) aligned towards the target 303 (or optionally, if, for example, a thinner coating is desired, also aligned away from the target 303). The control of the tilting of the mirror substrate must be faster than the rotational speed of the rotational movement of the coating holder 302 carrying the mirror substrates 306.

[0060] In further embodiments, the tilting of the mirror substrates according to the invention can also be carried out in such a way that gaps or spaces between adjacent mirror substrates during the coating process are at least partially shaded as a result of the tilting, i.e., lie in the shadow of the coating. This is illustrated in the schematic representations of Figs. 4a-4b. While, according to Fig. 4a, coating material can penetrate through gaps between adjacent mirror substrates 406 to reach and contaminate mechanical components 407 located behind them, according to Fig. 4b, the mechanical components 407 are protected as a result of a suitable tilting and the resulting shadowing.

[0061] If necessary, the vapor deposition angle distribution can be narrowed by additionally using a diaphragm and / or the rate of supply of coating material from the at least one target ("sputtering rate") can be varied over time, so that in phases of unfavorable vapor deposition angles (in the sense of the contamination possibility described above), the amount of coating material reaching the respective mirror substrate is reduced. Figs. 5a-5b show (again in plan view of a coating holder 502 with mirror substrates 506 and a target 503) in a schematic representation of a scenario in which the above-described shading of gaps located between adjacent mirror substrates 506 succeeds (Fig. 5a) or fails (Fig. 5b) depending on the rotational position of the coating holder 502. In this case, in the rotational position of the coating holder 502 according to Fig.5b (in which gaps 506a between the mirror substrates 506 are not shadowed) the rate of supply of coating material from the at least one target (“sputtering rate”) is reduced in order to avoid contamination of mechanical components located behind the gaps by coating material.

[0062] In further embodiments, the movement path of the coating holder can also be designed such that the mirror substrates are not located vertically above the target at any time during the coating process, wherein in particular a rotational movement may only occur around a single (spin) rotation axis.

[0063] Fig. 6 shows a schematic meridional section of the possible structure of a microlithographic projection exposure system designed for operation in the EUV.

[0064] According to Fig. 6, the projection exposure system 1 comprises an illumination device 2 and a projection lens 10. One embodiment of the illumination device 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a module separate from the other illumination device. In this case, the illumination device does not include the light source 3.

[0065] 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 can be displaced, in particular in a scanning direction, via a reticle displacement drive 9. A Cartesian xyz coordinate system is shown in Fig. 6 for explanatory purposes. The x-direction runs perpendicular to the drawing plane. The y-direction runs horizontally and the z-direction runs vertically. The scanning direction in Fig. 6 runs along the y-direction. The z-direction runs perpendicular to the object plane 6. The projection lens 10 is used to image the object field 5 into an image field 11 in an image plane 12. A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the region of the image field 11 in the image plane 12. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced via a wafer displacement drive 15, in particular along the y-direction.The displacement of the reticle 7 on the one hand via the reticle displacement drive 9 and the wafer 13 on the other hand via the wafer displacement drive 15 can be synchronized with each other.

[0066] Radiation source 3 is an EUV radiation source. Radiation source 3 emits, in particular, EUV radiation, which is also referred to below as useful radiation or illumination radiation. The useful radiation has, in particular, a wavelength in the range between 5 nm and 30 nm. Radiation source 3 can be, for example, a plasma source, a synchrotron-based radiation source, or a free-electron laser (FEL). The illumination radiation 16 emanating from the radiation source 3 is bundled by a collector 17 and propagates through an intermediate focus in an intermediate focal plane 18 into the illumination optics 4. The illumination optics 4 has a deflection mirror 19 and, downstream of this in the beam path, a first facet mirror 20 (with schematically indicated facets 21) and a second facet mirror 22 (with schematically indicated facets 23).The facet mirrors 21, 22 can be produced, for example, using the method according to the invention or using a coating system according to the invention.

[0067] The projection lens 10 has a plurality of mirrors Mi (i = 1, 2, ...), which are numbered according to their arrangement in the beam path of the projection exposure system 1. In the example shown in Fig. 6, the projection lens 10 has six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or a different number of mirrors Mi are also possible. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection lens 10 is a doubly obscured optic. The projection lens 10 has a numerical aperture on the image side that is greater than 0.5 and can also be greater than 0.6 and can be, for example, 0.7 or 0.75.

[0068] Although the invention has been described with reference to specific embodiments, numerous variations and alternative embodiments will become apparent to those skilled in the art, e.g., by combining and / or interchanging features of individual embodiments. Accordingly, it will be understood by those skilled in the art that such variations and alternative embodiments are encompassed by the present invention, and the scope of the invention is limited only by the appended claims and their equivalents.

Claims

Patent claims 1. Method for producing a mirror arrangement with a plurality of mirror elements, in particular for microlithography, - wherein, in a coating process carried out in a coating system (100), coating material is supplied from at least one target (103, 203, 303, 403, 503) to a plurality of mirror substrates (106, 206, 306, 406) for the deposition of a respective layer system on each of the mirror substrates (106, 206, 306, 406); and - wherein the mirror substrates (106, 206, 306, 406) are tilted by a tilt angle that can be individually adjusted for each mirror substrate in order to individually adjust the thickness profile generated in the coating process.

2. Method according to claim 1, characterized in that the tilting is carried out in such a way that a systematic coating error of the coating system (100) is at least partially corrected via the thickness profiles generated for the plurality of mirror substrates (106, 206, 306, 406).

3. Method according to claim 1 or 2, characterized in that the tilting is carried out in such a way that an alignment error of the mirror substrates in the coating system (100) is at least partially corrected via the thickness profiles generated for the plurality of mirror substrates (106, 206, 306, 406).

4. Method according to one of claims 1 to 3, characterized in that the tilting is carried out in such a way that different thickness profiles are generated for the plurality of mirror substrates (106, 206, 306, 406).

5. Method according to one of the preceding claims, characterized characterized in that the tilting is carried out in such a way that constant thickness profiles are generated for the individual mirror substrates (106, 206, 306, 406).

6. Method according to one of the preceding claims, characterized in that by changing an average deposition angle in the coating process, at least one further layer property, in particular roughness, crystallinity or layer stress, is varied in addition to the layer thickness profile.

7. Method according to one of the preceding claims, characterized in that the mirror substrates (106, 206, 306, 406) are moved in the coating process along a predetermined movement path relative to the target (103, 203, 303, 403, 503).

8. The method according to claim 7, characterized in that the tilt of the individual mirror substrates (106, 206, 306, 406) is varied during a single pass of the movement path.

9. Method according to claim 8, characterized in that this variation takes place in such a way that the respective mirror substrate (106, 206, 306, 406) is tilted towards the target (103, 203, 303, 403, 503) during the entire passage of the movement path or is tilted away from the target (103, 203, 303, 403, 503) during the entire passage of the movement path.

10. Method according to one of the preceding claims, characterized in that the mirror substrates (106, 206, 306, 406) are rotated during the coating process, wherein the tilting takes place as a function of the respective angle of rotation of this rotation. 1 1. Method according to one of the preceding claims, characterized in that the tilting is carried out in such a way that between adjacent Gaps located on mirror substrates (106, 206, 306, 406) are at least partially shaded as a result of the tilting in the coating process.

12. Method according to one of the preceding claims, characterized in that the supply of coating material from the at least one target (103, 203, 303, 403, 503) takes place at a time-varying rate.

13. Method according to one of the preceding claims, characterized in that the mirror arrangement is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm.

14. Mirror arrangement, in particular for microlithography, characterized in that it is manufactured using a method according to one of the preceding claims.

15. Coating system for producing a mirror arrangement, in particular for microlithography, with a process chamber, wherein in this process chamber (101) are arranged: • at least one target (103, 203, 303, 403, 503) for providing coating material; • a coating holder (102) for holding a plurality of mirror substrates (106, 206, 306, 406); • a first drive unit (108) for performing a translational movement of the coating holder (102); • a second drive unit (109) for performing a rotational movement of the coating holder (102); and • a third drive unit (110) for individually adjustable tilting of the mirror substrates (106, 206, 306, 406) during the coating process.

16. Microlithographic projection exposure apparatus with an illumination device and a projection lens, wherein the illumination device illuminates a mask located in an object plane of the projection lens during operation of the projection exposure apparatus and the projection lens projects structures on this mask onto a surface located in an image plane of the projection lens, wherein the projection exposure apparatus comprises at least one mirror arrangement which is produced by a method according to one of claims 1 to 13.

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