Mirrors with layer stress compensation

Abstract

The invention relates to a mirror (100) for a lithography system (600, 700), comprising a mirror body (101) comprising a substrate (102), a multi-layered reflective layer system (103) and an optical surface (104), and comprising at least one controller. The controller is configured to control at least one manipulator (105) such that it introduces a time-varying compensation force, at least in certain areas, into the mirror body (101), which is directed against a deformation of the mirror body (101) based on a time-varying layer stress. The invention further relates to a method for operating the mirror (100) and a projection exposure system with at least one mirror.

Description

[0001] The invention relates to a mirror for a lithography system, in particular for a projection exposure system or an illumination system, comprising a mirror body comprising a substrate, a multilayered reflective coating system, and an optical surface designed to reflect electromagnetic radiation, in particular electromagnetic radiation in the EUV range, as well as a controller. Furthermore, the invention relates to a method for operating the mirror and a projection exposure system.

[0002] Projection exposure systems are used to create extremely fine structures, particularly on semiconductor devices or other microstructured components. The operating principle of these systems is based on the creation of ultra-fine structures down to the nanometer range by means of a generally reduced-size image of structures on a mask, a so-called reticle, onto a wafer, which is coated with photosensitive material. The minimum dimensions of the generated structures depend directly on the wavelength of the light used. This light is shaped in an illumination optic to optimally illuminate the reticle. Recently, light sources with emission wavelengths in the nanometer range, for example between 1 nm and 120 nm, particularly in the 13.5 nm range, have been increasingly used. This wavelength range is also known as the EUV range.

[0003] The microstructured components are manufactured not only using EUV systems but also with established DUV systems operating at wavelengths between 100 nm and 400 nm, particularly 193 nm. The increasing demand for ever smaller structures has further raised the requirements for optical correction within these systems.

[0004] The optical elements for the projection exposure system, in particular the mirrors or EUV mirrors, comprise a reflective coating system applied to the substrate and consisting of multiple layers. These multiple layers are subject to mechanical stress, i.e., layer stress, which leads to parasitic deformation of the mirror body, causing its surface shape to deviate from a predetermined shape. While these deviations can be partially compensated for or at least reduced by reworking the mirror surface, the layer stress relaxes over the lifetime of the multilayer mirror. Therefore, the adjustments made may no longer be optimal at a later time, potentially leading to imaging errors in the projection exposure system.

[0005] Furthermore, adaptive mirrors are known from the prior art in which the optical surface is deformed, at least in certain areas, by means of actuators in order to shape an incoming wavefront. For examples, reference is made to DE 10 2019 201 147 A1, DE 10 2016 209 847 A1, EP 1 191 377 B1 and DE 10 2017 208364 A1.

[0006] Furthermore, DE 10 2015 219 977 A1 is known, which describes a method for joining several layers with different coefficients of thermal expansion. The introduction of mechanical stress is terminated by means of an external deformation device.

[0007] Therefore, the object of the present invention is to provide a mirror, a method for operating a mirror and a projection exposure system in which the aforementioned disadvantages are eliminated or reduced.

[0008] The problem relating to the mirror is solved by a mirror having the features of claim 1. The problem relating to the method is solved by a method having the features of claim 16. The problem relating to the projection exposure system is solved by a projection exposure system having the features of claim 19. Advantageous embodiments with expedient further developments are specified in the dependent claims.

[0009] The mirror is characterized in particular by the fact that the controller is configured to control at least one manipulator in such a way that it introduces a time-varying compensating force, at least in certain areas, into the mirror body. This force opposes, and thus acts against, a deformation of the mirror body based on a time-varying layer stress. The controller is therefore configured to adapt the compensating force introduced into the mirror body by the at least one manipulator to a time-varying deformation resulting from a time-varying layer stress of the reflective coating system. This allows the effect of relaxation—that is, the change in layer stress over time—and thus a change in the resulting parasitic deformation of the mirror surface over the mirror's lifetime to be taken into account during compensation.

[0010] It is particularly advantageous if the mirror body has an optically active area and a peripheral area that at least partially surrounds the optically active area, and if the at least one manipulator is arranged such that the compensation force acts on the peripheral area to more than 50%, preferably more than 70%, and most preferably more than 80%. The optically active area is understood to be that surface of the optical element which is illuminated by electromagnetic radiation when an image of a structure is projected onto an object.It has been found that the deformation due to the layer tension between the individual layers or due to the change in layer tension over the lifetime of the mirror is greatest in the edge region, i.e. outside the optically active area, so that it is advantageous if the compensation of the layer tension acting in the mirror body acts mainly or exclusively in the edge region.

[0011] In this context, it is preferred if the at least one manipulator is arranged in the edge region. In particular, it is advantageous if the at least one manipulator is arranged exclusively in the edge region, i.e., does not protrude into the optically active area, or only to a minimal extent. If multiple manipulators are present, it is preferred if the manipulators are preferably arranged in the edge region, particularly spaced apart from one another. Alternatively, the manipulators, or at least one manipulator, can also be arranged exclusively in the edge region. The edge region can have sub-regions that differ in density, i.e., in the number of manipulators per area. The at least one manipulator can, for example, be arranged in a recess located in the edge region.The manipulator can act exclusively on a local area, particularly a portion of the boundary region. Alternatively, the manipulator can also be applied across the entire area, meaning it extends over both the active area and the boundary region. Furthermore, it is also possible for the manipulator to extend across the entire area, encompassing the active area and at least a portion of the boundary region.

[0012] Furthermore, it has proven advantageous if the at least one manipulator is designed to overlap the edge region, at least in part. The at least one manipulator preferably projects beyond the edge region on the outer circumference of the mirror body.

[0013] Furthermore, it is preferred if, in addition to the at least one manipulator, at least one deformation actuator is provided which is configured to deform the optical working surface, at least partially. In other words, it is preferred if the mirror is designed as an adaptive mirror which, in addition to the at least one manipulator for compensating the layer stress, has at least one deformation actuator for deforming the optical working surface, i.e., the optically active area, at least partially.

[0014] In this context, it is advantageous if the at least one deformation actuator acts on the optically active area to at least 70%, preferably at least 80%, and particularly preferably at least 90%, and if the at least one manipulator acts on the edge region of the mirror body to at least 70%, preferably at least 80%, and particularly preferably at least 90%. The at least one deformation actuator is preferably configured as a piezostrictive, electrostrictive, magnetostrictive, thermostrictive, or photostrictive actuator. A plurality of deformation actuators, spaced apart from one another and, in particular, having a planar form, are particularly preferred.The at least one deformation actuator is preferably arranged between the mirror body and the optical surface, wherein a protective layer, which is opaque to electromagnetic radiation in the EUV and / or DUV range, can additionally be arranged between the actuator and the optical surface. Furthermore, it is advantageous if the deformation actuator is configured to exert a force acting perpendicular to the surface of the optical surface.

[0015] Furthermore, it is preferred if at least one manipulator is designed as a flat surface.

[0016] Preferably, the at least one manipulator is configured as a piezoelectric, electrostrictive, magnetostrictive, thermostrictive, or photostrictive actuator. Alternatively or additionally, the manipulator can also be configured as a mechanical actuator. For example, the at least one manipulator can be configured as a ring, a tire, a clamp, or a screw clamp. Alternatively or additionally, the at least one manipulator can also be configured as a fluid channel, in particular a heating channel or a cooling channel.

[0017] Furthermore, it is advantageous to have multiple manipulators. These manipulators can all be identical, or they can be different, particularly different types of manipulators.

[0018] Furthermore, it is preferred if the at least one manipulator or the plurality of manipulators are arranged between the mirror substrate and the optical surface. Alternatively or additionally, it is advantageous if the at least one manipulator or a plurality of manipulators are arranged around the outer circumference of the mirror body, at least partially. Particularly preferably, the at least one manipulator surrounds the mirror body on its outer circumference.

[0019] Furthermore, it is preferred if at least one of the manipulators is arranged between the mirror substrate and the optical surface, and at least one further actuator is arranged circumferentially around the mirror body, at least in some areas. In this context, it has proven advantageous if the at least one manipulator arranged between the mirror substrate and the optical surface is a piezoelectric, electrostrictive, magnetostrictive, thermostrictive, or photostrictive actuator, while the at least one manipulator arranged circumferentially is a mechanical actuator, in particular a ring, a hoop, a clamp, or a screw clamp.

[0020] Furthermore, it is advantageous if at least one manipulator is set up to introduce the compensation force laterally, i.e. parallel to the optical surface, into the mirror body, while the deformation actuator is set up so that the force for area-wise deformation of the optical surface acts surface-normal to the optical surface.

[0021] Preferably, a plurality of manipulators are present, wherein at least two of the manipulators differ from each other in their size and / or extent and / or in their material or type.

[0022] The inventive method for operating a mirror, in particular a mirror as described above, comprises in particular the following steps: a. Causing at least one manipulator to introduce a compensating force into a mirror body, based on a previously read or detected layer stress, and directed against a deformation of the mirror body, as well as b. Adjusting the compensation force to be applied by the at least one manipulator when the detected or expected layer stress changes by a predetermined or predeterminable value.

[0023] Using the method according to the invention, it is possible to compensate for or at least reduce a time-varying deformation based on a layer stress that changes over the lifetime of the mirror by adjusting the compensation force introduced into the mirror body by the at least one manipulator to a detected or anticipated, i.e., time-varying, layer stress. In other words, the controller causes the control signal for the at least one manipulator to be adjusted depending on the layer stress. The layer stress, and thus the change in the layer stress, can be measured either directly or indirectly. For this purpose, the layer stress or the change in the layer stress can be measured on the optical element itself or on a reference object, for example, using strain gauges. If the layer stress or the change in the layer stress is measured on a reference object (e.g.,If the coating stress (e.g., a reference mirror) is determined, this is preferably carried out beforehand as a calibration. The coating stress and its change over time can then be read into the controller. Subsequently or concurrently, the compensation force required to compensate for or at least reduce the deformation of the mirror body caused by the coating stress or changes in the coating stress is determined. This value or these values ​​serve as the controller's control signal for the control of at least one manipulator.

[0024] The layer stress can also be determined indirectly, i.e., by measuring a quantity that allows conclusions to be drawn about the layer stress. This quantity could, for example, be an optical aberration of the mirror if the mirror is part of an optical system. A wavefront measurement can be used to deduce the optical aberration of the optical system. If the aberration of the optical system is known without the aberration caused by the change in layer stress, or if this aberration can be determined or estimated separately, then the layer stress or the change in layer stress can be deduced.

[0025] Alternatively or additionally, the expected layer stress can also be determined using a simulation, artificial intelligence or self-learning algorithms and then read into the controller.

[0026] Another alternative is to capture (i.e., calculate, model, or estimate) the optical effect that the at least one manipulator has, i.e., the optical effect caused by the force being applied by the manipulator, and to use this as a correction factor for an optical system encompassing the mirror.

[0027] Alternatively or additionally, the compensation force of at least one manipulator can also be adjusted after a predetermined or predefinable period of time, in particular after predetermined time intervals, which can be regular or irregular. Specifically, the times and the compensation force required at each time can be determined based on calibration and / or simulation.

[0028] Furthermore, it is advantageous within the scope of the invention if a plurality of manipulators are provided, wherein the manipulators are divided into at least two control groups. The control groups can be controlled separately by means of the controller. For example, the different control groups can be caused to exert different compensating forces on the areas assigned to them. Areas with differing layer stresses or differing changes in layer stress can consequently be subjected to different compensating forces or different changes in compensating force. Alternatively, areas with the same or approximately the same layer stresses can each have at least one manipulator assigned to separate control groups.

[0029] Furthermore, it is advantageous if the profile of the layer stress over time is determined by means of measurement or simulation, and if the compensation force to be introduced by means of one manipulator is adjusted if the determined layer stress or the profile of the layer stress deviates from a predetermined or predeterminable limit value, in particular if it is greater or less than a predetermined or predeterminable limit value.

[0030] A projection exposure system with at least one mirror according to the invention. The at least one mirror is preferably designed as an EUV mirror. The advantages and embodiments of the mirror are also applicable to the projection exposure system comprising the mirror.

[0031] Optical system with at least one mirror according to the invention. The advantages and embodiments of the mirror are also applicable to the optical system comprising the mirror.

[0032] Lighting system with at least one mirror according to the invention. The at least one mirror is preferably designed as an EUV mirror. The advantages and embodiments of the mirror are also applicable to the lighting system comprising the mirror.

[0033] Further features, properties, and advantages of the present invention are described in more detail below with reference to exemplary embodiments and the accompanying figures. All features described so far and below are advantageous both individually and in any combination. The exemplary embodiments described below are merely examples and do not limit the scope of the invention. The figures show: Fig. 1a a schematic representation of a microlithographic projection exposure system designed for operation in the EUV, Fig. 1b a schematic representation of a microlithographic projection exposure system designed for operation in DUV, Fig. 2 a schematic representation of a first embodiment of a mirror according to the invention, Fig. 3 a schematic representation of a second embodiment of a mirror according to the invention, Fig. 4 a schematic representation of a third embodiment of a mirror according to the invention, Fig. 5 a schematic representation of a fourth embodiment of a mirror according to the invention, Fig. 6 a schematic representation of a fifth embodiment of a mirror according to the invention, Fig. 7 a schematic representation of a sixth embodiment of a mirror according to the invention, and Fig. 8 a schematic representation of a seventh embodiment of a mirror according to the invention.

[0034] Fig. Figure 1a shows a schematic representation of an exemplary projection exposure system 600 designed for operation in the EUV, in which the present invention can be implemented.

[0035] According to Fig. 1a A lighting device in a projection exposure system 600 designed for EUV has a field facet mirror 603 and a pupil facet mirror 604. The light from a light source unit, which comprises a plasma light source 601 and a collector mirror 602, is directed onto the field facet mirror 603. In the light path after the pupil facet mirror 604, a first telescope mirror 605 and a second telescope mirror 606 are arranged. Further down the light path is a deflecting mirror 607, which directs the incident radiation onto an object field in the object plane of a projection lens comprising six mirrors 651-656. At the location of the object field, a reflective structure-bearing mask 621 is arranged on a mask table 620, which is imaged into an image plane by means of the projection lens, in which a substrate 661 coated with a light-sensitive layer (photoresist) is located on a wafer table 660.

[0036] The invention can be used in a DUV system as well as in Fig. 1b is shown. A DUV system is basically the same as the EUV system described above. Fig. 1a constructed, wherein mirrors and lenses can be used as optical elements in a DUV system and the light source of a DUV system emits useful radiation in a wavelength range of 100 nm to 400 nm.

[0037] The in Fig. The DUV lithography system 700 shown in Figure 1b has a DUV light source 701. For example, an ArF excimer laser can be used as the DUV light source 701, emitting radiation 702 in the DUV range at, for example, 193 nm. A beam shaping and illumination system 703 directs the DUV radiation 702 onto a photomask 704. The photomask 704 is designed as a transmissive optical element and can be located outside the system 703. The photomask 704 has a structure which is reduced in size and projected onto a wafer 706 or the like by means of the projection system 705. The projection system 705 has several lenses 707 and / or mirrors 708 for imaging the photomask 704 onto the wafer 706. Individual lenses 707 and / or mirrors 708 of the projection system 705 can be arranged symmetrically to the optical axis 709 of the projection system 705.It should be noted that the number of lenses 707 and mirrors 708 of the DUV lithography system 700 is not limited to the number shown. More or fewer lenses 707 and / or mirrors 708 may be used. In particular, the beam shaping and illumination system 703 of the DUV lithography system 700 has several lenses 707 and / or mirrors 708. Furthermore, the mirrors are typically curved on their front surface for beam shaping. An air gap 710 between the last lens 707 and the wafer 706 can be replaced by a liquid medium with a refractive index > 1. The liquid medium can be, for example, highly purified water. Such a setup is also called immersion lithography and offers increased photolithographic resolution.

[0038] Fig. Figure 2 shows a first embodiment of a mirror 100, in particular an EUV mirror, with a mirror body 101 comprising a substrate 102, a multilayer reflective coating system 103, and an optical surface 104. Furthermore, a controller (not shown in detail) is provided, which is configured to control at least one manipulator 105 such that the latter introduces a time-varying compensating force, at least in certain areas, into the mirror body 101. This force acts against a deformation of the mirror body 101 that is based on a time-varying coating stress. The controller is therefore configured to adapt a compensating force introduced into the mirror body 101 by means of the at least one manipulator 105 to a time-varying deformation resulting from a time-varying coating stress.This makes it possible to take into account the effect of relaxation, i.e. the change in layer tension over time, and thus a change in the resulting parasitic deformation of the mirror surface over the lifetime of the mirror 100 during compensation.

[0039] In this case, the manipulator 105 is formed as a flat surface and is arranged between the substrate and the reflective layer system 103. The reflective layer system 103 can have a protective layer on the side facing the manipulator 105, which is opaque to EUV radiation and / or DUV radiation. Fig. 2. The manipulator 105 is made of a piezoelectric, electrostrictive, magnetostrictive, thermostrictive, or photostrictive material. Furthermore, several manipulators 105, made of a piezoelectric, electrostrictive, magnetostrictive, thermostrictive, or photostrictive material, may be present. These may be spaced apart from one another or connected directly to each other. The manipulators 105 can be controlled together, separately, or in groups. The manipulators 105 may also be of different types, meaning they may have different sizes and / or different elongation properties and / or be made of different materials.The manipulators exert a tensile or compressive force which counteracts a deformation of the mirror body caused by the layer stress, in particular of the reflection layer system 103, and thus compensates for or at least reduces it.

[0040] Fig. Figure 3 shows a further embodiment of the mirror 100. The mirror body 101 has an optically active area 106 and a border area 107 that at least partially surrounds the optically active area 106. The manipulator or manipulators 105 are preferably arranged such that the compensation force acts on the border area 107 to more than 50%, preferably more than 70%, and particularly preferably more than 80%. The optically active area 106 is understood to be the surface of the mirror 100 that is illuminated by the electromagnetic radiation when an image of a structure is projected onto an object. The mirror 100 includes an optical axis that is perpendicular to the optically active surface, i.e., the optically active area 106, preferably at a vertex of the mirror 100.It has been found that the deformation due to the layer stress between the individual layers of the reflective coating system 103, or also due to the change in layer stress over the lifetime of the mirror 100, is greatest in the edge region 107, i.e., outside the optically active region 106. In this case, the manipulator 105 is arranged exclusively in the edge region 107. However, it can optionally also be designed to project into the optically active region 106.

[0041] Furthermore, multiple manipulators 105 may be present, arranged exclusively in the boundary region 107. The boundary region 107 may also have sub-regions that differ in density, i.e., in the number of manipulators 105 per area. The at least one manipulator 105 may, for example, be arranged in a recess in the boundary region 107. In particular, the manipulator 105 may also act exclusively locally on a sub-region, especially a sub-region of the boundary region 107.

[0042] The one in Fig. The embodiment shown in Figure 4 differs in that the at least one manipulator 105 is designed to overlap the edge region 107 at least in certain areas. The at least one manipulator 105 thus projects beyond the edge region 107 on its outer circumference.

[0043] Furthermore, as in Fig. Figure 5 shows that, in addition to at least one manipulator 105, at least one deformation actuator 108 must be present, which is configured to deform the optical working surface 104, at least in certain areas. In other words, the mirror 100 is the Fig. 5 formed as an adaptive mirror which, in addition to the at least one manipulator 105 for compensating the deformation caused by the layer stress or change in layer stress, has at least one further deformation actuator 108 for at least partial deformation of the optical working surface 104, in particular of the optically active area 106.

[0044] The at least one deformation actuator 108, i.e., the force provided by it, preferably acts on the optically active area to at least 70%, more preferably to at least 80%, and particularly preferably to at least 90%, while the at least one manipulator 105, i.e., the compensating force provided by the manipulator 105, acts on the edge region 107 of the mirror body 101 to at least 70%, more preferably to at least 80%, and particularly preferably to at least 90%. The at least one deformation actuator 105 is preferably configured as a piezostrictive, electrostrictive, magnetostrictive, thermostrictive, or photostrictive actuator. Particularly preferably, and not shown in detail, a plurality of deformation actuators 108 are provided, which are arranged at intervals from one another.In this case, the entire cross-sectional area of ​​the mirror exhibits deformation actuators; however, it is also possible that only a region, in particular the optically active region 106, exhibits deformation actuators 108. The at least one deformation actuator is, analogous to the manipulator 105, arranged between the mirror body 101 and the reflective coating system 103. The reflective coating system 103 may have a protective layer on the side facing the manipulator 105 / deformation actuator 108, which is opaque to EUV radiation and / or DUV radiation. Furthermore, the deformation actuator 108 exerts a force acting perpendicular to the optical surface 104. Alternatively, it is also possible that the deformation actuator 108 exerts a force acting parallel to the optical surface 104.The at least one deformation actuator 108 can be formed identically to the at least one manipulator 105; for example, both can be piezoelectric actuators. Alternatively, they can of course be differently formed actuators.

[0045] The exemplary embodiment according to Fig. 6 differs in that the at least one manipulator 105 is formed as a fluid channel 110, in particular as a heating channel or as a cooling channel. The fluid channel 110 can also be used to temperature control the mirror 100.

[0046] The exemplary implementations according to the Fig. 7 and Fig. 8 differ from the preceding embodiments in that the at least one manipulator 105 is formed as a mechanical manipulator 109. For example, and as in the Fig. As shown in Figure 7, the manipulator 105 can be formed as a ring or as a rim. The ring or rim is arranged around the outer circumference of the mirror body 101, at least partially. In this case, the at least one mechanical manipulator 109 surrounds the mirror body 101, in particular the mirror edge 111, on its outer circumference. The compensation force thus acts laterally on the mirror body 101.

[0047] In the embodiment according to the Fig.Figure 8 shows a plurality of manipulators 105, wherein at least two of the manipulators 105 differ from one another. One of the manipulators 105 is designed as a mechanical manipulator 109, in particular as a clamp or a screw clamp. The mechanical manipulator 109 clamps the mirror body at the mirror edge 111 and thus acts locally on a partial area of ​​the mirror's edge region. Additionally, at least one further manipulator 105 is provided, which is arranged between the substrate and the reflective coating system 103 in the active optical area. This manipulator 105 or these manipulators 105 are preferably made of a piezoelectric, electrostrictive, magnetostrictive, thermostrictive, or photostrictive material. In this case, the compensating forces provided by the manipulators 105 act surface normal to the optical working surface 104.Depending on the choice of manipulators 105, one of the manipulators 105 can also act laterally, i.e. perpendicular to the surface normal and parallel to the optical working surface 104.

[0048] The method according to the invention comprises in particular the following steps: at least one manipulator 105 is caused by the controller to introduce a compensating force into a region of the mirror body 101, wherein the compensating force is based on a previously read or detected layer stress and is directed against the deformation of the mirror body 101 caused by the layer stress. The controller adjusts the compensating force to be introduced by the at least one manipulator 105 at a later time, if necessary, when the detected or expected layer stress changes by a predetermined or predeterminable value or deviates from a predetermined or predeterminable limit value.This makes it possible to compensate for, or at least reduce, a time-varying deformation based on a changing layer stress over the lifetime of the mirror 100 by adapting the compensation force to be introduced into the mirror body 101 by the at least one manipulator 105 to a detected or expected, i.e., time-varying, layer stress. In other words, the controller causes an adjustment of the control signal for the at least one manipulator 105 depending on the layer stress.

[0049] The coating stress, and thus also any change in the coating stress, can preferably be detected either by means of strain gauges, or a previously detected coating stress can be read in, and from this a necessary compensation force to be introduced into the mirror body 101 by means of the at least one manipulator 105 can be determined. Thus, a calibration can be carried out beforehand by measuring the coating stress or the change in coating stress over the lifetime of a reference mirror. Subsequently or concurrently, the compensation force required to compensate for or reduce the deformation of the mirror body 101 caused by the coating stress or the change in coating stress is determined. This value or these values ​​are read into the controller to control the at least one manipulator 105.The manipulators 105 can be controlled together or separately. Accordingly, the controller can assign different control signals to each or a group of manipulators 105, so that different manipulators 105 introduce different compensating forces into the mirror body 101. For each manipulator 105, an individual compensating force can therefore be determined and specified at any given time in order to compensate for or at least reduce the deformation or change in deformation caused by the layer stress or the change in layer stress across the entire mirror surface 101 or even in individual areas. Alternatively, the controller can also assign the same control signals to two or all groups of manipulators 105.

[0050] Alternatively or additionally, the expected layer stress can also be determined using simulation, artificial intelligence, or self-learning algorithms. Furthermore, the layer stress can also be indirectly measured and read in. For example, if the mirror is part of an optical system, the optical error of the optical system can be measured, e.g., using wavefront measurement, and the change in layer stress can then be deduced. Moreover, the compensation force of the at least one manipulator 105 can also be adjusted after a predetermined or predefinable period of time, in particular at predetermined time intervals, which can be regular or irregular. Specifically, the times and the compensation force required at each time can be determined based on calibration and / or simulation.

[0051] Furthermore, the layer stress over time can be determined by measurement or simulation. The compensation force applied by means of at least one manipulator can be adjusted if the layer stress deviates from a predetermined or predefinable limit value. REFERENCE MARK LIST 100 mirrors 101 Mirror bodies 102 Substrat 103 reflective layers 104 optical effective area 105 Manipulator 106 optically active areas 107 peripheral areas 108 Deformation actuator 109 mechanical actuator 110 Fluid channel 111 Mirror edge 600 Projection exposure system 601 Plasma light source 602 Collector mirrors 603 Field faceted mirror 604 pupil facet mirrors 605 first telescope mirror 606 second telescope mirror 607 Deflection mirror 620 mask table 621 Mask 651 Mirror (projection lens) 652 Mirror (projection lens) 653 Mirror (projection lens) 654 Mirror (projection lens) 655 Mirror (projection lens) 656 Mirror (projection lens) 660 wafer table 661 coated substrate 700 DUV lithography system 701 DUV light source 702 DUV radiation / beam path 703 Beam shaping and illumination system (DUV) 704 Photomask 705 Projection System 706 wafers 707 lens 708 mirrors 709 optical axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2019 201 147 A1

[0005] DE 10 2016 209 847 A1

[0005] EP 1 191 377 B1

[0005] DE 10 2017 208364 A1

[0005] DE 10 2015 219 977 A1

[0006]

Claims

[1] Mirror (100) for a lithography system (600,700), with a mirror body (101) comprising a substrate (102), a multi-layered reflection layer system (103) and an optical active surface (104), and with at least one controller, characterized by in that the controller is configured to control at least one manipulator (105) in such a way that it introduces a time-variable compensation force into the mirror body (101) at least in some regions, which compensation force is directed counter to a deformation of the mirror body (101) based on a time-variable layer stress. [2] Mirror (100) according to claim 1, characterized bythat the mirror body (101) has an optically active region (106) and an edge region (107) which at least partially surrounds the optically active region (106), and that the at least one manipulator (105) is arranged such that the compensation force acts to more than 50% on the edge region (107). [3] Mirror (100) according to claim 1 or 2, characterized by that the at least one manipulator (105) is arranged in or on the edge region (107). [4] Mirror (100) according to one of claims 1 to 3, characterized by that the at least one manipulator (105) projects at least partially beyond the edge region (107) on the outer circumference of the mirror body (101). [5] Mirror (100) according to one of claims 1 to 4, characterized by in that in addition to the at least one manipulator (105) there is at least one deformation actuator (108) which is designed to deform the optical active surface (106) at least in some regions. [6] Mirror (100) according to claim 5, characterized by that the at least one deformation actuator acts to at least 70% on the optically active region (106) and that the at least one manipulator (105) acts to at least 70% on the edge region (107) of the mirror body (101). [7] Mirror (100) according to one of claims 1 to 6, characterized by that at least one manipulator is flat. [8] Mirror (100) according to one of claims 1 to 7, characterized by that the at least one manipulator (105) is formed as a piezostrictive, electrostrictive, magnetostrictive, thermostrictive or photostrictive actuator. [9] Mirror (100) according to one of claims 1 to 8, characterized by that the at least one manipulator (105) is formed as a mechanical actuator (109). [10] Mirror (100) according to one of claims 1 to 9, characterized bythat the at least one manipulator (105) is formed as a ring or as a tire or as a clamp or as a screw clamp. [11] Mirror (100) according to one of claims 1 to 10, characterized by that the at least one manipulator (105) is formed as a fluid channel (110). [12] Mirror (100) according to one of claims 1 to 11, characterized by that the at least one manipulator (105) or an additional manipulator (105) is arranged at least in regions around the outer circumference of the mirror edge (111). [13] Mirror (100) according to one of claims 1 to 12, characterized by that the at least one manipulator (105) is arranged between the mirror substrate (102) and the optical active surface (104). [14] Mirror (100) according to one of claims 1 to 13, characterized bythat the at least one manipulator (105) is arranged to introduce the compensation force into the mirror body (101) parallel to the optical effective surface (104). [15] Mirror (100) according to one of claims 1 to 14, characterized by that a plurality of manipulators (105) are present and that at least two of the manipulators (105) differ from one another in their size and / or extent and / or in their material. [16] Method for operating a mirror (100) comprising the steps: a. causing the at least one manipulator (105) to introduce a compensation force into a mirror body (101), which compensation force is based on a previously read or detected layer tension and which is directed against a deformation of the mirror body (101), and b. Adjusting the compensation force to be introduced by the at least one manipulator (105) when the detected or expected layer stress changes by a predetermined or predeterminable value. [17] Method according to claim 16, characterized by that the compensation force is adjusted after a specified or specifiable period of time. [18] Method according to claim 16 or 17, characterized by that a course of the layer stress over time is determined by means of a measurement or a simulation, and that the compensation force to be introduced by means of the at least one manipulator is adjusted if the determined values ​​of the layer stress or the course of the layer stress deviates from a predetermined or predeterminable limit value. [19] Projection exposure apparatus with at least one mirror according to one of claims 1 to 15.

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