Mirror, in particular for microlithographic projection exposure apparatuses

Abstract

The invention relates to a mirror, in particular for a microlithographic projection exposure apparatus. The mirror of the invention has an optically effective surface (101, 201, 301); a mirror substrate (110, 210, 310, 410); a reflective layer system (120, 220, 320) for reflecting electromagnetic radiation incident on the optically effective surface (101, 201, 301); at least one actuator layer configured to transmit an adjustable mechanical force on the reflective layer system (120, 220, 320), thereby generating a locally variable deformation of the optically effective surface (101, 201, 301); and at least one cooling device configured to at least partially dissipate heat generated by the actuator layer.

Description

TECHNICAL FIELD

[0001] The present invention relates to mirrors, in particular to mirrors for microlithographic projection exposure apparatuses. BACKGROUND

[0002] Microlithography is used to produce microstructured components, for example integrated circuits or LCDs. Microlithography processes are carried out in so-called projection exposure apparatuses which have an illumination device and a projection lens. In this case, an image of a mask (reticle) illuminated by means of the illumination device is projected by means of the projection lens onto a substrate (for example 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.

[0003] In projection lenses designed for the EUV range (i.e. wavelengths of approximately 13 nm or approximately 7 nm), mirrors are used as optical components of the imaging process, since suitable, light-transmissive refractive materials are not available.

[0004] One problem which arises in practice is that EUV mirrors heat up and thus deform in a manner dependent thereon, in particular as a result of the absorption of the radiation emitted by the EUV light source, which in turn has a negative effect on the imaging properties of the optical system. This is particularly true if illumination settings with a relatively small illumination pole (for example, in dipole or quadrupole illumination settings) are used, in which the heating or deformation of the mirror varies strongly over the optically effective surface of the mirror.

[0005] By way of example, variations in the gravitational force depending on the location or geographical position of the system are another reason for aberrations occurring in the aberration process of the projection exposure apparatus.

[0006] It is particularly known that, in order to at least partially compensate for the above-mentioned problems, and generally also in order to improve the image position accuracy and the image quality (both along the optical axis, or in the direction of light propagation, and also in the lateral direction, or perpendicular to the optical axis or the direction of light propagation), one or more mirrors in an EUV system are designed as adaptive (i.e. actively deformable) mirrors. Such adaptive mirrors can in particular comprise an actuator layer made of piezoelectric material, wherein a locally varying electric field is generated on the piezoelectric layer by applying a voltage to electrodes arranged on both sides of the piezoelectric layer. In the event of a local deformation of the piezoelectric layer, the reflective layer stack of the adaptive mirror is also deformed, as a result of which imaging aberrations (which can also be time-varying) can be at least partially compensated for by appropriately controlling the voltage applied to the electrodes.

[0007] While the above principle of adaptive mirrors can be effective in terms of aberration correction in combination with a deformation or actuation of the mirror to some extent, the problem with the requirement of a greater actuation or deformation is that the high voltages of piezoelectric actuation lead to a parasitic heat in the layer structure of the mirror, which can in particular lead to an undesired deformation of the mirror, but also to a so-called "d 33 coefficient" which is not controlled, wherein the d 33 coefficient is characteristic of the piezoelectric layer expansion caused by the voltage and thus also of the actuation effect of the mirror deformation. The d 33 coefficient is defined here as ΔD = d 33 * U, wherein ΔD denotes the (absolute) thickness change and U denotes the voltage.

[0008] A further consequence of high voltages, for example above 20 V, on piezoelectric actuation can be damage to the piezoelectric layer and a reduction in the service life.

[0009] With regard to the prior art, reference can be made, for example, only to WO 2018 / 177649 Al. SUMMARY

[0010] It is an object of the present application to provide a mirror, in particular for a microlithographic projection exposure apparatus, which can be deformed or actuated by a displacement distance required, for example, for aberration correction, while at least partially avoiding the above-mentioned problems.

[0011] This object can be achieved, for example, by a mirror according to the features of the independent claim 1.

[0012] According to the present application, the mirror having an optically effective surface has:

[0013] a mirror substrate;

[0014] a reflective layer system for reflecting electromagnetic radiation incident on the optically effective surface;

[0015] at least one actuator layer configured to transmit an adjustable mechanical force on the reflective layer system, thereby producing a locally variable deformation of the optically effective surface; and

[0016] at least one cooling device configured to at least partially dissipate heat generated by the actuator layer.

[0017] The mirror can in particular be a mirror for a microlithographic projection exposure apparatus. However, the present application is not limited thereto. In other applications, for example in systems for mask metrology, mirrors according to the present application can also be employed or utilized.

[0018] The present embodiments are particularly based on the concept of providing, in an adaptive mirror having an actuator layer configured to transmit an adjustable mechanical force onto a reflective layer system and thereby to generate a locally variable deformation of an optically effective surface, a cooling device configured to at least partially dissipate heat generated by the layer, in order to achieve a more stable, more secure and more precise operation of the adaptive mirror and thus to improve the correction of imaging aberrations provided by the adaptive mirror.

[0019] The effect of a more precise operation of the adaptive mirror achieved with the cooling concept of the present invention is particularly due to a better definition of the functionality of the actuator layer, since the material parameters of the actuator layer (in particular the d 33 coefficients of the piezoelectric layer mentioned above) related to the mechanical force transmitted onto the reflective layer system can be kept essentially constant (although these parameters in principle have a temperature dependence).

[0020] The effect of a more precise operation of the adaptive mirror achieved with the cooling concept of the present invention is also due to the fact that the combination of heating and cooling (which is realizable, for example, if the mirror comprises a segmented heating configuration configured to heat- induced locally variable deformation of the optically effective surface) can make the reaction of the adaptive mirror significantly faster compared to simple heating without cooling.

[0021] Furthermore, the cooling concept of the present invention allows to increase the heat introduced into the mirror for actuation (for example, in order to achieve a larger displacement distance of the piezoelectric layer), while effectively avoiding heat-induced damage by the cooling, thus always ensuring a particularly secure operation of the adaptive mirror.

[0022] According to an embodiment, the at least one actuator layer comprises a piezoelectric or a second order electrostrictive layer, wherein an electric field can be applied to the piezoelectric or second order electrostrictive layer to generate the locally variable deformation of the optically effective surface.

[0023] According to an embodiment, the at least one actuator layer is configured between the mirror substrate and the reflective layer system.

[0024] According to an embodiment, the at least one actuator layer is configured on the side of the mirror substrate opposite to the reflective layer system.

[0025] According to an embodiment, the cooling device comprises at least one cooling channel configured in the mirror substrate.

[0026] According to an embodiment, the distance between the at least one cooling channel and a boundary delimiting the mirror substrate in a direction perpendicular to the optically effective surface is less than 20 mm, in particular less than 10 mm.

[0027] If the mirror comprises an actuator layer in the form of a piezoelectric layer arranged between the mirror substrate and the reflective layer system, it is particularly advantageous if at least one cooling channel is arranged in the mirror substrate close to its boundary facing the reflective layer system in order to dissipate heat from the piezoelectric layer in a particularly effective manner. If the mirror comprises an actuator layer in the form of a piezoelectric layer or a second-order electrostrictive layer arranged on the side of the mirror substrate opposite the reflective layer system, it is particularly advantageous if at least one cooling channel is arranged in the mirror substrate close to its boundary facing away from the reflective layer system or to its boundary facing the mirror back side in order to effectively dissipate heat from the piezoelectric layer.

[0028] According to an embodiment, the mirror further comprises a controller configured to control operation of the cooling device in dependence on operation of the actuator layer.

[0029] According to an embodiment, the mirror further comprises a segmented heating arrangement configured to thermally induce local variable deformation of the optically effective surface.

[0030] According to an embodiment, the controller is further configured to control operation of the cooling device in dependence on operation of the segmented heating arrangement.

[0031] According to an embodiment, the segmented heating arrangement comprises an electrode arrangement configured to be electrically driven to thereby thermally induce the deformation of the optically effective surface.

[0032] According to an embodiment, the segmented heating arrangement comprises at least one radiation source configured to irradiate the mirror substrate using electromagnetic radiation to thereby thermally induce the deformation of the optically effective surface.

[0033] According to an embodiment, the mirror is designed for an operating wavelength of less than 250 nm, in particular less than 200 nm, more particularly less than 160 nm.

[0034] According to an embodiment, the mirror is designed for an operating wavelength of less than 30 nm, in particular less than 15 nm.

[0035] The invention further relates to an optical system of a microlithographic projection exposure apparatus, in particular an illumination device or a projection lens, comprising at least one mirror having the above-mentioned features, and also to a microlithographic projection exposure apparatus.

[0036] Further configurations of the invention can be gathered from the detailed description and the dependent claims.

[0037] The invention will be explained in more detail below on the basis of exemplary embodiments shown in the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0038] In the drawings:

[0039] Figure 1A schematic diagram illustrating the construction of an adaptive reflector according to an embodiment of the present invention is shown, the reflector comprising an actuator layer in the form of a piezoelectric layer;

[0040] Figure 2 A schematic diagram illustrating the construction of an adaptive mirror according to another embodiment of the present invention is shown, the mirror comprising an actuator layer in the form of a piezoelectric or second-order electrostrictive layer;

[0041] Figures 3a-3b A schematic diagram illustrating the construction of an adaptive reflector according to another embodiment of the present invention is shown, the reflector comprising a segmented heating configuration having an electrode arrangement;

[0042] Figure 4 A schematic diagram illustrating the construction of an adaptive reflector according to another embodiment of the present invention is shown, the reflector comprising a segmented heating configuration having a radiation source;

[0043] Figure 5 A schematic diagram showing a possible configuration of a microlithography projection exposure apparatus designed for operation under EUV is displayed; and

[0044] Figure 6 A schematic diagram of a possible configuration for a microlithography projection exposure apparatus designed for operation under DUV is shown. Detailed Implementation

[0045] The following describes different embodiments of an adaptive mirror with an actuator layer configured to transmit adjustable mechanical forces on the reflective layer system, thereby producing locally variable deformation of the optically effective surface. These embodiments share a common feature: providing a cooling device configured to at least partially dissipate the heat generated by the actuator layer to achieve stable, safe, and accurate operation of the adaptive mirror, and thus improve the correction of imaging aberrations provided by the adaptive mirror.

[0046] Figure 1 A schematic diagram illustrating the construction of a reflector according to the invention in one embodiment is shown. The reflector 100 may be an EUV reflector of an optical system, particularly a projection lens of a microlithography projection exposure apparatus or an EUV reflector of an illumination device, but the invention is not limited thereto.

[0047] The mirror 100, having an optically effective surface 101, specifically includes a mirror substrate 110, which is made of any desired suitable mirror substrate material. Suitable mirror substrate materials are, for example, titanium dioxide-doped (TiO2) quartz glass, such as those marketed under trade names... Materials sold by Corning Incorporated. Another suitable mirror substrate material is, for example, lithium-aluminum-silicon oxide-glass ceramic, for example, under the trade name... The materials sold by (Schott AG). The reflector 100 further includes a reflective layer stack 120 (e.g., a multilayer system made of molybdenum and silicon layers).

[0048] This invention is not limited to the specific configuration of this layer stack; merely as an example, a suitable construction may comprise about fifty layers or groups of layers in a layer system, wherein the layer system comprises a molybdenum (Mo) layer with a thickness of 2.4 nm and a silicon (Si) layer with a thickness of 3.4 nm. In a further embodiment, the mirror may also be configured for so-called grazing incidence. In this case, the reflective layer system may comprise, for example, particularly a single layer, which is composed of, for example, ruthenium (Ru) having an exemplary thickness of 30 nm.

[0049] During the operation of the optical system, electromagnetic EUV radiation (by...) Figure 1 (The arrow in the image indicates that) an impact on the optically effective surface 101 of the reflector 100 may cause non-uniform volume changes in the reflector substrate 110, which is caused by the temperature distribution resulting from the absorption of radiation that impacts the optically effective surface 101 non-uniformly.

[0050] The reflector 100 has a piezoelectric layer 130 between the reflector substrate 110 and the reflective layer system 120, wherein the piezoelectric layer 130 is made of a piezoelectric material, such as lead zirconate titanate (Pb(Zr,Ti)O3).

[0051] The piezoelectric layer 130 is disposed between the first electrode 140 and the second structured electrode 160, wherein the first electrode 140 is based on... Figure 1 An adhesive layer 150 (made of TiO2 in this example) is applied to the reflector substrate 110, wherein additional adhesive layers 151 and 152 (made of LaNiO3 in this example) are disposed between the electrodes 140 and 160 (made of platinum (PT) in this example) and the piezoelectric layer 130. The adhesive layers 151 and 152 are used to provide the best possible crystal growth conditions for the piezoelectric layer.

[0052] according to Figure 1 However, the invention is not limited thereto. The shielding layer 170 (in this example, it is made of platinum (PT), like the electrodes 140 and 160, and is selectively applied in principle) is further disposed on the bottom side of the reflective layer stack 120 facing the structured electrode 160. According to... Figure 1 The SiO2 layer 165 is disposed between the piezoelectric layer 130 and the shielding layer 170.

[0053] By applying a locally varying voltage, a locally varying deflection of the piezoelectric layer 130 can be generated, which in turn is converted into a deformation of the reflective layer stack 120 and thus into a wavefront variation of the light incident on the optically effective surface 101 and can be used for aberration correction.

[0054] The above-mentioned mirror substrate materials exhibit a so-called zero crossing temperature, in which the coefficient of thermal expansion has a zero crossing in its dependency on temperature, so that no or only negligible thermal expansion occurs. Thus, in certain cases, it can be desirable to keep the mirror 100 at this zero crossing temperature.

[0055] According to Figure 1 , the mirror 100 comprises a plurality of cooling channels 115, which are arranged in the mirror substrate 110 close to its boundary facing the reflective layer system 120, in order to dissipate heat from the piezoelectric layer 130 in a particularly effective manner. A cooling medium, for example water, flows through the cooling channels 115. In an exemplary embodiment, the distance between each of the cooling channels 115 and the boundary facing the reflective layer system 120 can be less than 20 mm, in particular less than 10 mm. Furthermore, the cooling power of the plurality of cooling channels 115 can be at least 0.1 W, in particular more than 0.5 W, and in particular more than 1 W.

[0056] Figure 2 A schematic diagram is shown to illustrate the construction of a mirror 200 according to the application in another embodiment of the application. According to Figure 2 , the mirror 200 differs from the previously described mirror 100 of Figure 1 in particular in the fact that the piezoelectric or second-order electrostrictive layer 230 is arranged on the side of the mirror substrate 210 opposite the reflective layer system 220.

[0057] According to Figure 2 , embodiments make use of a material exhibiting a second-order electrostrictive effect or of the d 31 coefficient of a piezoelectric material, a voltage applied along the surface normal, i.e. perpendicular to the optically effective surface 201, which uses electrodes not shown in Figure 2 , generates a mechanical stress in a direction parallel to the optically effective surface 201, i.e. perpendicular to the surface normal. This mechanical stress influences the deformation perpendicular to the optically effective surface 201.

[0058] In contrast, according to Figure 1 , embodiments make use of the d 33 coefficient, a voltage applied along the surface normal, i.e. perpendicular to the optically effective surface 101, directly leads to a deformation in a direction perpendicular to the optically effective surface 101, i.e. parallel to the surface normal.

[0059] Furthermore, according toFigure 2 In one embodiment, a piezoelectric or second-order electrostrictive layer 230 is disposed on the side of the reflector substrate 210 opposite to the reflective layer system 220 (i.e., the back side of the reflector 200), while Figure 1 One embodiment has a piezoelectric layer 130 between the substrate and the reflective layer system 120.

[0060] It can be set in the layer structure of the reflector 200 Figure 2 Additional functional layers not shown in the diagram (such as diffusion barrier layers, adhesion enhancement layers, etc.).

[0061] because Figure 2 This is only a simplified description of this embodiment; refer to the above description. Figure 1 The description of the material of the piezoelectric or second-order electrostrictive layer 230 and the description of the materials and effects of other possible functional layers that may exist in the reflector 200 are also included. Specifically, PZT(=Pb(Zr) x Ti 1-x O3 can be used for layer 230. Another material that can be used for layer 230 is PMN (=Pb(Mg)). 1 / 3 Nb 2 / 3 )O3).

[0062] Although the reflector 200 also includes multiple cooling channels 215, these cooling channels 215 are configured in the reflector substrate 210 near its boundary away from the reflector layer system 220 or at the boundary facing the back side of the reflector in order to dissipate heat from the piezoelectric layer 230 in a particularly effective manner.

[0063] Figures 3a-3b and Figure 4 A schematic diagram illustrating the construction of a reflector according to a further embodiment of the present invention is shown. These embodiments share the common feature of a segmented heating configuration configured to thermally induce localized variable deformation of the optically effective surface.

[0064] To correct unwanted volume changes or other aberrations that occur during operation of the microlithography projection exposure equipment due to the absorption of radiation that non-uniformly impacts the optically effective surface 301, according to Figure 3a The reflector 300 includes an electrode configuration 380 having a plurality of electrodes 381, which are electrically drivable or capable of having a selectively configurable current applied to them via electrical leads 382. Furthermore, the reflector 300 includes a conductive layer 385. Similar to... Figure 2 The reflector 300 may also optionally include a piezoelectric or second-order electrostrictive layer 330 disposed on one side of the reflector substrate 310 opposite to the reflector layer system 320.

[0065] exist Figure 3aIn this context, "365" denotes a smoothing and insulating layer, which in particular electrically insulates the electrodes 381 of the electrode configuration 380 from one another, and which can for example be made of quartz glass (SiO2).

[0066] Likewise, Figure 3a Additional functional layers (for example, for example diffusion barrier layers, adhesion enhancement layers, etc.) not depicted in the layer structure of the mirror 300 can also be provided in the layer structure of the mirror 300.

[0067] During operation of the mirror 300, different potentials can be applied to the individual electrodes 381 of the electrode configuration 380, wherein the voltage arising between the electrodes 381 thereby generates an electric current by means of the electrically conductive layer 385. Depending on the potentials applied to the individual electrodes 381, respectively, the heat caused by the electric current results in a locally varying heating of the mirror surface.

[0068] According to Figure 3a Embodiments according to the application are not limited to the specific geometry of the electrode configuration 380. The electrodes 381 can be provided in any suitable distribution (for example, a Cartesian grid, a hexagonal configuration, etc.). In further embodiments, the electrodes 381 can also be positioned only in specific regions. Figure 3b An example of the geometry of the electrode configuration 380 is exemplarily shown in the context.

[0069] According to the application, in the case of the mirror 300, the combined use of the electrode configuration 380 and the electrically conductive layer 385 (despite the comparatively coarse structure of the electrode configuration) enables a continuous variation of the power input into the mirror, wherein, at the same time, the coupling-in of thermal power (for example, in comparison with the use of infrared (IR) heating devices) is limited to the mirror itself. Due to the material selection, there is a comparatively high electrical resistance in the electrically conductive layer 385, so that the voltage drops there, whereas due to the comparatively significantly higher electrical conductivity in the leads 382, there is no voltage or heat drop in the leads 382, and in this respect no fine structure is required to produce a high electrical resistance.

[0070] According to Figure 3a The mirror 300 comprises a plurality of cooling channels 315, which are configured in the mirror substrate 310 close to its boundary facing the reflective layer system 320, in order to dissipate heat from the electrically conductive layer 385 in a particularly effective manner.

[0071] Figure 4 A schematic diagram is shown to illustrate the configuration of a mirror according to a further embodiment of the application. According to Figure 4The mirror 400 (which is shown in a very simplified manner only) differs from the previously described mirror 300 in particular by the fact that the segmented heating arrangement 480 comprises a plurality of radiation sources 481 which are configured to irradiate the mirror substrate 410 with electromagnetic radiation, thereby thermally inducing a deformation of the optically effective surface. Depending on the operation of the individual radiation sources 481 (which can be controlled independently of one another), the radiation leads to a locally varying heating of the mirror surface. The wavelength of the electromagnetic radiation (which can for example be infrared radiation) is such that the material of the mirror substrate 410 is substantially transparent in the corresponding wavelength range.

[0072] According to Figure 4 , the mirror 400 comprises a plurality of cooling channels 415 which are configured in the mirror substrate 410 close to the boundary thereof which faces the reflective layer system (not shown in Figure 4 ) in order to dissipate heat from the mirror in a particularly effective manner.

[0073] Furthermore, the design and configuration of the radiation sources 481 is preferably such that the radiation does not (or at least to a large extent not) interfere with the cooling channels 415

[0074] Figure 5 A schematic diagram of an exemplary projection exposure apparatus is shown, which is designed for operation in the EUV and in which the present application can be implemented. According to Figure 5 , the illumination device in the projection exposure apparatus 500 designed for the EUV comprises a field facet mirror 503 and a pupil facet mirror 504. Light from a light source unit comprising a plasma light source 501 and a collector mirror 502 is directed onto the field facet mirror 503. A first telescope mirror 505 and a second telescope mirror 506 are configured in the beam path downstream of the pupil facet mirror 504. A deflection mirror 507 is configured downstream of the beam path, which deflection mirror directs the radiation incident thereon onto an object field in an object plane of a projection lens comprising six mirrors 551-556. A mask 521 with a reflective structure on a mask table 520 is configured at the position of the object field, which mask is imaged into an image plane by means of the projection lens, wherein a substrate 561 coated with a photosensitive layer (photoresist) on a wafer table 560 is arranged in the image plane.

[0075] Figure 6A schematic diagram of an exemplary projection exposure apparatus designed for operation in DUV and in which the present invention can be implemented is shown. The projection exposure apparatus 600 includes a beam shaping and illumination system 610 and a projection lens 620. In this case, DUV stands for “deep ultraviolet light” and indicates that the wavelength of the working light is between 30 nm and 250 nm. The beam shaping and illumination system 610 and the projection lens 620 may be configured in a vacuum enclosure and / or surrounded by a machine room with corresponding drive units. The projection exposure apparatus 600 has a DUV light source 601. For example, an ArF excimer laser emitting radiation 602 in the 193 nm DUV range may be provided as the DUV light source 601.

[0076] Figure 6 The beam shaping and illumination system 610 shown directs DUV radiation 602 onto a mask 605. The mask 605 is implemented as a transmissive optical element and can be configured outside the beam shaping and illumination system 610 and the projection lens 620. The mask 605 has a structure that images onto a substrate or wafer 630 in a reduced manner via the projection lens 620. The projection lens 620 has multiple lens elements (…). Figure 6 Three lens elements 621-623 and at least one reflector are shown schematically and exemplary. Figure 6 Two mirrors (624, 625) are schematically and exemplary shown for imaging the mask 605 onto the wafer 630. In this case, the individual lens elements 621-623 of the projection lens 620 and / or mirrors 624, 625 may be configured symmetrically with respect to the optical axis OA of the projection lens 620. It should be noted that the number of lens elements and mirrors in the DUV lithography apparatus 600 is not limited to the number shown in the figure. More or fewer lens elements and / or mirrors may also be provided. Furthermore, the front side of the mirrors is typically curved for beam shaping. The air gap between the last lens element 623 and the wafer 630 may be replaced by a liquid medium 626 with a refractive index greater than 1. For example, the liquid medium 626 may be high-purity water. This configuration is also known as immersion microlithography and has higher optical lithography resolution.

[0077] Even though the invention has been described based on specific embodiments, many variations and alternative embodiments will be apparent to those skilled in the art, for example, through combinations and / or exchanges of features of the various embodiments. Therefore, it is beyond doubt that the invention also includes such variations and alternative embodiments, and that the scope of the invention is limited only to the meaning of the appended patent claims and their equivalents.

Claims

1. A reflector having an optically effective surface, comprising: Reflector substrate (110, 210, 310, 410); A reflective layer system (120, 220, 320) is used to reflect electromagnetic radiation incident on the optically effective surface (101, 201, 301); At least one actuator layer configured to transmit adjustable mechanical force on the reflective layer system (120, 220, 320), thereby producing localized variable deformation of the optically effective surface (101, 201, 301); At least one cooling device configured to at least partially dissipate the heat generated by the actuator layer; and The segmented heating configuration is configured to thermally induce localized variable deformation of the optically effective surface (301).

2. The reflector as described in claim 1, characterized in that, The at least one actuator layer includes a piezoelectric or second-order electrostrictive layer (130, 230, 330), wherein an electric field can be applied to the piezoelectric or second-order electrostrictive layer to produce the local variable deformation of the optically effective surface (101, 201, 301).

3. The reflector as described in claim 1 or 2, characterized in that, The at least one actuator layer is disposed between the reflector substrate (110) and the reflective layer system (120).

4. The reflector as described in claim 1 or 2, characterized in that, The at least one actuator layer is disposed on the side of the reflector substrate (210, 310) opposite to the reflector layer system (220, 320).

5. The reflector as described in any one of the preceding claims, characterized in that, The cooling device includes at least one cooling channel (115, 215, 315, 415) disposed in the reflector substrate (110, 210, 310, 410).

6. The reflector as described in claim 5, characterized in that, In the direction perpendicular to the optically effective surface, the distance between the at least one cooling channel (115, 215, 315, 415) and the boundary defining the reflector substrate (110, 210, 310, 410) is less than 20 mm, and in particular less than 10 mm.

7. The reflector as described in any one of the preceding claims, characterized in that, The reflector further includes a controller configured to control the operation of the cooling device based on the operation of the actuator layer.

8. The reflector as described in claim 7, characterized in that, The controller is further configured to control the operation of the cooling device based on the operation of the segmented heating configuration.

9. The reflector as claimed in any of the preceding claims, characterized in that, The segmented heating configuration includes an electrode configuration (380) configured to be electrically driven to thermally induce the deformation of the optically effective surface (301).

10. The reflector as claimed in any of the preceding claims, characterized in that, The segmented heating configuration includes at least one radiation source (481) configured to irradiate the mirror substrate (410) with electromagnetic radiation, thereby thermally inducing the deformation of the optically effective surface.

11. The reflector as described in any one of the preceding claims, characterized in that, The mirror is designed for operating wavelengths less than 250 nm, particularly less than 200 nm, and even more particularly less than 160 nm.

12. The reflector as described in any one of the preceding claims, characterized in that, This mirror is designed for operating wavelengths less than 30 nm, and especially less than 15 nm.

13. The reflector as described in any one of the preceding claims, characterized in that, This mirror is used in microlithography projection exposure equipment.

14. An optical system, particularly an illumination device or projection lens for a microlithography projection exposure apparatus, characterized in that, The optical system has a reflector as described in any one of the preceding claims.

15. A microlithography projection exposure apparatus (500, 600) having an illumination device and a projection lens, characterized in that, The projection exposure device has the optical system as described in claim 14.

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