Projection exposure system and method for correcting temperature influences by influencing the surface shape of an optical element

Abstract

Projection exposure system (400, 100) comprising a projection lens (408, 107, 200) wherein the projection lens (408, 107, 200) comprises an optical device (1), wherein the optical device (1) comprises an optical element (2) with an optically effective surface (2a) and at least one electrostrictive actuator (3) which is deformable by applying a control voltage, wherein the electrostrictive actuator (3) is functionally connected to the optical element (2) in order to influence the surface shape of the optically effective surface (2a), wherein a control device (4) is provided to supply the electrostrictive actuator (3) with the control voltage, and wherein a measuring device (5) is provided, characterized in that the measuring device (5) is configured to measure, at least temporarily, while the electrostrictive actuator (3) influences the optically effective surface (2a) of the optical element (2),to directly and / or indirectly measure and / or determine the temperature and / or temperature change of the electrostrictive actuator (3) and / or its environment in order to take into account a temperature-dependent influence when the electrostrictive actuator (3) is controlled by the control device (4), wherein the measuring device (5) comprises temperature sensors (8) that measure the temperature and / or the temperature change and / or the temperature distribution of the electrostrictive actuator (3) and / or its environment, and wherein the temperature sensors (8) are arranged on a rear side (3a) of the electrostrictive actuator (3) facing away from the optical element (2).

Description

[0001] The invention relates to a projection exposure system which has a projection lens comprising an optical device comprising an optical element with an optically effective surface and at least one electrostrictive actuator which is deformable by applying a control voltage, and a temperature sensor which is arranged directly on the optical device or in close proximity to the optical device.

[0002] The invention further relates to a method for controlling a projection exposure system by influencing the surface shape of an optically effective surface of an optical element, wherein the optical element is part of a projection lens and the projection lens is part of the projection exposure system, and wherein the optical element is functionally connected to an electrostrictive actuator.

[0003] The invention further relates to a projection exposure system for semiconductor lithography with an illumination system comprising a radiation source and optics, which includes at least one optical device.

[0004] Due to the ongoing miniaturization of semiconductor circuits, the demands on the resolution and accuracy of projection exposure systems are increasing accordingly. Correspondingly high demands are also placed on the optical elements, which, among other things, influence the beam path within the projection exposure system.

[0005] To achieve high resolution, especially with lithography optics, EUV light with a wavelength of 13.5 nm is used in addition to VUV wavelengths and DUV wavelengths of 248 nm and 193 nm, respectively.

[0006] EUV projection systems employ mirror systems that operate either at near-perpendicular incidence or grazing incidence, while mirrors in VUV and DUV systems operate at perpendicular incidence. Achievable resolutions are constantly increasing, resulting in correspondingly higher demands on wavefront correction. Increasingly subtle effects are becoming significant, leading to a growing need for passive, and especially active, correction methods.

[0007] Locally deformable mirrors are known for operating EUV projection systems. The local deformation is achieved by piezoelectric elements, which are designed as actuators in the form of thin plates, films, or layers. For example, see US 2002 004 890 6 A1.

[0008] Local deformation of mirrors by electrostrictive material, piezoelectric material, piezorestrictive material, pyroresistive material, magnetorestrictive material is known from US 7 492 077 B2.

[0009] In DE 10 2015 213 275 A1 a mirror arrangement for lithography exposure systems is disclosed, the mirror elements of which can be piezoelectrically controlled for the compensation of wavefront errors.

[0010] The object positioning system described in WO 2020 / 207684 A1 includes a predominantly electrostrictive actuator system by which a surface can be deformed, as well as a measuring device for the mechanical condition of the actuator.

[0011] NL 2 025 093 A discloses a projection exposure system. It describes a system in which a mirror has a deformable reflective surface. Furthermore, an actuator system with a plurality of actuators is provided. The actuators can each be made of a material with predominantly electrostrictive properties.

[0012] The present invention is based on the objective of providing a device for correcting imaging errors of a projection lens of a projection exposure system, in which the imaging errors can be corrected with high adjustment accuracy.

[0013] The present invention is also based on the objective of providing a method for influencing the surface shape of an optically effective surface of an optical element, with which the optically effective surface can be influenced with high adjustment accuracy, wherein the optical element is part of a projection lens which is part of a projection exposure system.

[0014] The present invention also aims to provide a projection exposure system for semiconductor lithography, which has a projection lens, wherein the projection lens has at least one optical device which has an optical element to correct imaging errors with high focusing accuracy.

[0015] The problem is solved for the projection exposure system by the features listed in claim 1. The problem is solved for the method for influencing the surface shape of an optically effective surface of an optical element arranged in the projection exposure system by the features of claim 19.

[0016] The dependent claims and the features described below relate to advantageous embodiments and variants of the invention.

[0017] The optical device comprises an optical element with an optically effective surface and at least one electrostrictive actuator, which is deformable by applying a control voltage. The electrostrictive actuator is functionally connected to the optical element to influence the surface shape of the optically effective surface. A control device is provided to supply the electrostrictive actuator with the control voltage.

[0018] In this context, an optical element is preferably understood to be a deformable optical element, in particular an adaptive optical element. Preferably, the optical element is a lens, and more preferably a mirror, in particular a locally deformable mirror.

[0019] The optical element, in particular a lens element or a mirror element, is an optical element of a projection lens, wherein the projection lens is part of a projection exposure system.

[0020] The optical setup of the projection exposure system includes a measuring device which is designed to directly measure and / or indirectly determine the temperature and / or temperature changes of the electrostrictive actuator and / or its surroundings, at least temporarily, while the electrostrictive actuator is influencing the optically effective surface of the optical element, in order to take into account a temperature-dependent influence when the electrostrictive actuator is controlled by the control device.

[0021] By directly measuring and / or indirectly determining the temperature and / or a temperature change of the electrostrictive actuator and / or its environment according to the invention, it is possible to take into account a temperature-dependent influence when controlling the electrostrictive actuator.

[0022] From the data of the measuring device, a parasitic effect on the surface (e.g. a bimetallic effect) and / or a change in the refractive index of the optical element can be determined.

[0023] The data from the measuring device makes it possible to control the electrostrictive actuator with high accuracy. Based on the desired surface shape, a precise requirement for the applied electrical control voltage or the electric field strength can be derived.

[0024] The measuring device makes it possible to measure a temperature distribution in the electrostrictive actuator itself and / or in the environment of the electrostrictive actuator.

[0025] The environment of the electrostrictive actuator is understood to be an area that is so close to the electrostrictive actuator that the temperature of the electrostrictive actuator and / or a temperature change of the electrostrictive actuator can be derived from its temperature.

[0026] Within the scope of the invention, it may be provided that the temperature and / or the temperature change is measured. Within the scope of the invention, it is not absolutely necessary to measure an absolute temperature; it may be sufficient to measure a temperature change in order to take temperature-dependent influences into account when controlling the electrostrictive actuator.

[0027] The optical design of the projection exposure system makes it possible to reduce temperature-dependent influences, in particular influences caused by the irradiation of the optical element or resulting from the heat generated by the electrostrictive actuator during operation.

[0028] Within the framework of the solution according to the invention, it may be sufficient to influence areas or sections of the optically effective surface by means of the at least one electrostrictive actuator.

[0029] Within the framework of the solution according to the invention, it may be sufficient if the electrostrictive actuator is functionally connected to the optical element in such a way that the surface shape of the optically effective surface can be influenced at least in a defined area.

[0030] The solution according to the invention provides that the electrostrictive actuator can be deformed, in particular expanded and / or shrunk, by applying a control voltage.

[0031] The control unit is designed to set a desired deformation of the optically effective surface of the optical element, taking into account the data from the measuring device, and to control the electrostrictive actuator accordingly.

[0032] The expansion constants of electrostrictive materials can be highly temperature-dependent. By measuring the temperature, temperature change, or temperature distribution of the electrostrictive actuator, the actuator material's response to temperature changes can be incorporated into the actuator's control.

[0033] All measurement methods proposed within the scope of the present invention can be used as alternatives or in any combination. It is therefore also possible to combine more than two measurement methods.

[0034] The temperature and / or temperature change determined within the framework of the solution according to the invention can be used to detect or determine the temperature distribution in the environment of the electrostrictive actuator and / or in the electrostrictive actuator in order to specifically take into account a temperature-dependent influence when controlling the electrostrictive actuator.

[0035] It is advantageous if the measuring device measures at least one of the following quantities: - the temperature and / or the temperature change of the electrostrictive actuator and / or - the temperature and / or the temperature change in the environment of the electrostrictive actuator and / or - temperature-dependent properties of the electrostrictive actuator, and / or - the change in the surface shape of at least one of the surfaces of the optical element when a specific control voltage is applied to the electrostrictive actuator.

[0036] From the data of the measuring device, in particular the determined temperature and / or temperature change, the deformation of the optically effective surface can be deduced, for example, by means of simulation and / or previously calculated tables and / or calibration. The simulation can specifically include a finite element analysis (FE analysis) based on a material model and the concrete design of the overall components, especially the mounting structures, the adhesive or solder joint, any components for position measurement, and the like.

[0037] Changes in the optically effective surface can be converted into aberrations of the projection lens.

[0038] It is advantageous if the electrostrictive actuator is designed in such a way that the application of the control voltage leads to a lateral deformation of the electrostrictive actuator in the plane of the electrostrictive actuator.

[0039] It may be provided that the control device is set up to adjust a value for an m31 or d31 coefficient characterizing the electrostrictive transverse effect for controlling the electrostrictive actuator, based on the data determined by the measuring device, in order to take into account the temperature-dependent influence.

[0040] It has proven particularly suitable to determine a current value for the m31 or d31 coefficient of the piezoelectric tensor based on the measured quantities and to take this into account when controlling the electrostrictive actuator.

[0041] It is advantageous if the measuring device measures continuously during the operation of the electrostrictive actuator.

[0042] In principle, it is possible for the measuring device to measure only intermittently during the operation of the electrostrictive actuator; however, it has proven advantageous for the measuring device to measure continuously during the operation of the electrostrictive actuator, so that measurements can be taken with time and location resolution during operation.

[0043] Measurements can preferably be carried out during operational breaks of the projection exposure system, such as those that regularly occur when changing the semiconductor substrate or mask due to manufacturing requirements, or when changing the setting of the lighting system of the projection exposure system.

[0044] According to the invention, the control device can be configured to take into account thermal changes in material parameters within the electrostrictive actuator and / or components in the vicinity of the electrostrictive actuator.

[0045] Because the control unit takes into account thermal changes in material parameters within the electrostrictive actuator and / or in components in the vicinity of the electrostrictive actuator, temperature-dependent influences on the control of the electrostrictive actuator can be comprehensively considered. The electrostrictive actuator can therefore be controlled with exceptionally high setting accuracy.

[0046] It has been recognized that it is advantageous to consider the thermal changes in stiffness and / or the thermal expansion of the adhesive or solder joint when controlling the electrostrictive actuator. Temperature-dependent influences of the adhesive or solder joint can thus be particularly advantageously taken into account when controlling the electrostrictive actuator. It is also possible, if appropriate, to consider the thermally induced changes in stiffness and / or expansion of other components involved, such as the substrate of the optical element.

[0047] In principle, the electrostrictive actuator can also be attached to the optical element in other ways; in this case, a temperature-dependent change in the mounting material and / or its thermal expansion can also be taken into account.

[0048] An arrangement of the electrostrictive actuator on a rear side of the optical element facing away from the optically effective surface has proven particularly suitable for influencing the optically effective surface if the optical element is a mirror of a projection lens which is part of a projection exposure system.

[0049] Within the aforementioned context of an optical element that is part of a projection lens, wherein the projection lens is part of a projection exposure system, it may be sufficient if the electrostrictive actuator is located in an area of ​​the back of the optical element.

[0050] According to the invention, it can further be provided that the electrostrictive actuator is arranged on the optically effective surface of the optical element outside a light area or on a side surface of the optical element.

[0051] Arranging the electrostrictive actuator on the optically effective surface of the optical element outside a light-sensitive area can be a suitable alternative or supplement to arranging it on the back side of the optical element. This is particularly advantageous when the electrostrictive actuator is used in lenses. However, it is also possible, in principle, to arrange the electrostrictive actuator on a back side facing away from the optically effective surface, especially outside a light-sensitive area, even in lenses. Alternatively or additionally, it is also possible to arrange the electrostrictive actuator on a side face of the optical element.

[0052] According to the invention, it can be provided that the electrostrictive actuator has a plurality of electrostrictive components.

[0053] The design of the electrostrictive actuator with a plurality of electrostrictive components has proven to be particularly suitable for influencing the optically effective surface in a suitable manner, for example also locally influencing it, in particular deforming it.

[0054] By designing the electrostrictive actuator with a plurality of electrostrictive components, a temperature distribution can be determined particularly advantageously by measuring or determining the temperature of the individual electrostrictive elements or groups of electrostrictive components. In this way, a temperature and / or a temperature change can be measured or determined.

[0055] The electrostrictive actuator can preferably be designed as an electrostrictive mat.

[0056] The electrostrictive actuator or electrostrictive mat can be made of or contain a suitable material, for example lead or magnesium niobate (PMN).

[0057] The electrostrictive actuator has electrostrictive components arranged in a regular pattern.

[0058] The electrostrictive actuator or the electrostrictive components of the electrostrictive actuator may preferably each have a multi-layered structure.

[0059] According to the invention, the measuring device can measure a capacitance and / or an electrical resistance and / or a frequency-dependent impedance of the electrostrictive actuator.

[0060] It has been recognized that measuring the temperature-dependent properties of the electrostrictive actuator or its individual components can be particularly advantageous. Based on these measurements, the temperature or temperature change of the electrostrictive actuator can then be determined or calculated. Using the relationship between the temperature change and the m31 or d31 coefficient, a suitable value for the m31 or d31 coefficient can be determined for controlling the electrostrictive actuator.

[0061] Within the scope of the invention, it is not necessary to directly determine a temperature and / or a temperature change. The temperature and / or the temperature change of the electrostrictive actuator can also be determined indirectly by measuring temperature-dependent properties. Measuring the local capacitance, the local electrical resistance, and / or the local frequency-dependent impedance of the electrostrictive actuator, or of individual electrostrictive components or a group of electrostrictive components of the electrostrictive actuator, has proven particularly suitable for this purpose. Other temperature-dependent properties can also be measured.

[0062] Measuring temperature-dependent properties, especially capacitance, has the advantage that few or no temperature sensors are required. Furthermore, the measurement is performed directly within the electrostrictive actuator itself, resulting in a correspondingly high level of accuracy.

[0063] According to the invention, the measuring device may include an infrared camera for temperature detection and / or an electrical bridge circuit for measuring temperature-dependent properties of the electrostrictive actuator.

[0064] Temperature measurement, or the measurement of temperature changes, can be performed, for example, using an infrared camera that captures the entire surface or parts of the optical element on which the electrostrictive actuator acts. The measurement can preferably be carried out continuously during operation.

[0065] Alternatively or additionally, at least one electrical bridge circuit can be used. The bridge circuit can preferably be operated with an alternating voltage of variable frequency.

[0066] According to the invention, it is further provided that the measuring device includes temperature sensors that measure the temperature and / or the temperature change of the electrostrictive actuator and / or its environment.

[0067] Insofar as the following text and the claims refer to temperature sensors (plural), this is a preferred embodiment of the invention. In principle, instead of several temperature sensors, only a single temperature sensor can also be provided.

[0068] Measuring the temperature and / or temperature change of the electrostrictive actuator has proven particularly suitable for obtaining a time- and location-resolved measurement result during operation.

[0069] The measured data can be used to determine the temperature distribution of the electrostrictive actuator and / or its environment.

[0070] The deformation of the optically effective surface can preferably be deduced from the measured data by means of simulation, previously calculated tables or calibration.

[0071] Temperature measurement can be used, based on a previously determined relationship between temperature and the m31 or d31 coefficient, to determine a current temperature-dependent value for the m31 or d31 coefficient with time and location resolution.

[0072] The temperature sensors make it possible to measure a locally and temporally varying temperature field in order to calculate a current value for the d based on these measurements. 31 -coefficients of the piezoelectric tensor that can be taken into account when controlling the electrostrictive actuator or the individual electrostrictive components of the electrostrictive actuator.

[0073] It is also possible to measure groups of electrostrictive components.

[0074] According to the invention, the temperature sensors are arranged on the back side of the electrostrictive actuator facing away from the optical element.

[0075] In addition, according to the invention, it can be provided that the temperature sensors are arranged on one side, preferably a side facing the electrostrictive actuator (particularly preferably the back side), of the optical element between electrostrictive components of the electrostrictive actuator.

[0076] It can be provided that the temperature sensors are arranged locally between the back side of the optical element and the electrostrictive components of the electrostrictive actuator and / or on the back side of the electrostrictive actuator or the electrostrictive components. Within the scope of the invention, it is not necessary for each electrostrictive component to be assigned a temperature sensor. It may be sufficient if temperature sensors are provided at preferably regular intervals or if each group of electrostrictive components is assigned a temperature sensor. The temperature sensor can preferably be arranged between two electrostrictive components and / or on the back side of one of the electrostrictive components.

[0077] According to the invention, it can be provided that the temperature sensors are configured to enable a resistance-based measurement such that the temperature sensors have a material whose resistance varies measurably with the temperature.

[0078] It is advantageous if the temperature sensors are set up to measure a temperature change of 0.1 K and greater, preferably of 0.03 K and greater, and more preferably of 0.01 K and greater.

[0079] The aforementioned design of the temperature sensors has proven to be particularly suitable for determining values ​​that enable appropriate control of the electrostrictive actuator or the individual electrostrictive components of the electrostrictive actuator.

[0080] According to the invention, it can be provided that supply lines to supply the electrostrictive actuator with the control voltage and supply lines to supply the temperature sensors with an operating voltage are at least partially routed together and / or are functionally and / or physically combined into a single conductor track and / or are identical.

[0081] Particularly in combination with a suitable control device, it can be advantageous to use essentially the same connections for supplying the temperature sensors as those which also supply the electrostrictive components with the control voltage.

[0082] The inventors recognized that it is advantageous if the electrical supply lines of the electrostrictive components and the electrical lines for the measurement signal of the temperature sensors are routed together, at least over sections, and in particular if they are functionally and / or physically combined into a single conductor track.

[0083] If other sensors or measuring points are provided in addition to or as an alternative to the temperature sensors, these can be supplied with electrical voltage in a comparable manner.

[0084] Within the scope of the invention, it can be provided that the optical device is used in a projection exposure system, and that a measuring system is engaged when the semiconductor substrate (wafer) is changed, which measures the image. Based on the measurement, corresponding corrections can then be made in the control of the electrostrictive actuator.

[0085] Within the scope of the invention, it can be provided that during the changing of the semiconductor substrate (wafer), the current state is measured once, and then a defined voltage is applied to the electrostrictive actuator. The change is then measured, making it possible to attribute the change to the deformation of the optically effective surface of the optical element, in particular a mirror. From the measurement result, it can thus be deduced how much the optically effective surface has deformed. From this, the temperature can also be determined, since the deviations from the expected result result from the temperature change. The difference between the expected measurement result and the measured measurement result can be attributed to the temperature, which is why it is also possible to determine the temperature in this way.to determine a temperature change and then control the electrostrictive actuator accordingly, so that the temperature change is compensated and the setting accuracy can thus be improved.

[0086] It is advantageous if the control unit determines an expected wavefront effect based on the data from the measuring device due to the change in surface shape and / or a change in refractive index, and takes the wavefront effect into account when controlling the electrostrictive actuator and / or at least one compensation device.

[0087] The inventors recognized the advantage of updating a location-dependent temperature distribution of the optical element based on the measurement information, determining the expected wavefront effect due to surface deformation and / or changes in refractive index, and taking this wavefront change into account when controlling at least one compensation device for low aberrations. This compensation device can be, in addition to the electrostrictive actuator, or alternatively, other actuators of the optical device or system.

[0088] According to the invention, the compensation means can be designed as elements that can be displaced in the direction of light or perpendicular to it, and / or as elements that can be rotated about the direction of light or about axes perpendicular to it, and / or as deformable elements, and / or as locally heated elements, and / or as locally cooled elements, and / or as elements that can be displaced relative to each other, preferably as aspherized plates, and / or as interchangeable elements.

[0089] The aforementioned compensatory measures have proven to be particularly suitable.

[0090] The measurement methods mentioned within the scope of the invention can be used alternatively or additionally. This applies in particular to combinations of methods for directly measuring a temperature, a temperature change, or a temperature distribution and methods in which temperature-dependent properties of the electrostrictive actuator or the individual electrostrictive components are measured and then a temperature, a temperature change, or a temperature distribution is determined from the measured values.

[0091] The aforementioned method, in which the change in surface shape is measured at a specific voltage applied to the electrostrictive actuator, can also be used in combination with the other aforementioned measurement methods.

[0092] It is advantageous if the optical element is a mirror, in particular a locally deformable mirror, especially of a projection exposure system.

[0093] The optical device according to the invention is particularly suitable for this purpose.

[0094] Regarding the advantageous designs and further developments of such a projection exposure system, reference is made to the aforementioned and also the following explanations.

[0095] The optical element is designed as a lens or mirror of a projection lens, the projection lens being part of a projection exposure system.

[0096] The invention further relates to a method for influencing the surface shape of an optically effective surface of an optical element, wherein the optical element is functionally connected to an electrostrictive actuator, and wherein the electrostrictive actuator, when supplied with a control voltage, is capable of influencing the surface shape of the optically effective surface. According to the invention, it is provided that, at least temporarily, while the electrostrictive actuator is influencing the optically effective surface of the optical element, the temperature and / or any temperature change of the electrostrictive actuator and / or its surroundings is measured directly and / or indirectly determined in order to account for a temperature-dependent influence on the control of the electrostrictive actuator. Here, the optical element is part of a projection lens, which is part of a projection exposure system.

[0097] The method according to the invention makes it particularly advantageous to take into account the temperature and / or a temperature change of the electrostrictive actuator or the individual electrostrictive components of the electrostrictive actuator during the control of the electrostrictive actuator, and to determine a temperature distribution from this. The surface shape of the optically effective surface can thus be influenced with particular precision. The electrostrictive actuator is connected to an optical element, which is part of a projection lens, the projection lens being part of a projection exposure system.

[0098] Regarding further features, designs and advantages, reference is made to the preceding and following explanations concerning the optical device.

[0099] It is advantageous if a parasitic effect on the surface shape of the optically effective surface and / or a change in the refractive index of the optical element can be determined from the measured data.

[0100] In a method, it may be provided that the application of an electrical voltage leads to a lateral deformation of the electrostrictive actuator in the plane of the electrostrictive actuator, and the measured data are used to adjust a value for an m31 or d31 coefficient characterizing the electrostrictive transverse effect for the control of the electrostrictive actuator in such a way that temperature-dependent influences are taken into account.

[0101] It may also be provided that the change in the surface shape of at least one of the surfaces of the optical element, in particular the optically effective surface, at a specific voltage applied to the electrostrictive actuator, in particular by measurable aberrations, is determined and the m31 or d31 coefficient is determined from this.

[0102] Alternatively or additionally, it may be advantageous to determine at least one temperature-dependent parameter of the electrostrictive actuator, in particular a capacitance and / or an electrical resistance and / or a frequency-dependent impedance, and to determine the m31 or d31 coefficient of the electrostrictive actuator from this.

[0103] From the measured or determined temperature data or the data on temperature changes, it is easy to determine the temperature distribution of the electrostrictive actuator or the temperatures and / or temperature changes of the individual electrostrictive components of the electrostrictive actuator and to take their influences into account accordingly.

[0104] As previously explained, the temperature distribution can be used to infer the deformation of the optically effective surface, preferably by simulation, using previously calculated lookup tables, or by calibration. In particular, the simulation can be performed using finite element analysis (FEA) methods based on a material model. The changes in the optically effective surface can be converted into aberrations, which can be done using previously calculated sensitivities.

[0105] Preferably, the inventive method is to be used for correcting imaging errors of a projection exposure system.

[0106] The method according to the invention is particularly suitable for correcting imaging errors of a projection exposure system for semiconductor lithography, in particular an EUV projection exposure system for semiconductor lithography.

[0107] The invention relates to a projection exposure system for semiconductor lithography with an illumination system comprising a radiation source and optics, which includes at least one optical device with an optical element for correcting imaging errors according to any one of claims 1 to 20. The optical device can be configured according to the preceding and following descriptions.

[0108] The invention is particularly suitable for use with microlithographic DUV ("Deep Ultra Violet") and EUV ("Extreme Ultra Violet") projection exposure systems.

[0109] An advantageous use of the invention also relates to immersion lithography, whereby imaging errors can be advantageously corrected.

[0110] It should also be noted that terms such as "comprehensive," "exhibiting," or "with" do not exclude other characteristics or steps. Furthermore, terms such as "a" or "that," which indicate a singular number of steps or characteristics, do not exclude a plurality of characteristics or steps—and vice versa.

[0111] Exemplary embodiments of the invention are described in more detail below with reference to the drawing.

[0112] The figures each show preferred embodiments in which individual features of the present invention are combined with one another. Features of an embodiment can also be implemented independently of the other features of the same embodiment and can therefore be readily combined by a person skilled in the art to form further meaningful combinations and subcombinations with features of other embodiments.

[0113] In the figures, functionally identical elements are provided with the same reference symbols.

[0114] They show schematically: Fig. 1 an EUV projection exposure system; Fig. 2 a DUV projection exposure system; Fig. 3 an immersion lithographic projection exposure system; Fig. 4 a cross-section through an optical device according to the invention comprising an optical element and an electrostrictive actuator; Fig. 5 an enlarged representation of detail V of the Fig. 4; Fig. 6 a representation according to Fig. 5 with one to Fig. 5 alternative arrangements of a temperature sensor; Fig. 7 a schematic representation of a cross-section through an optical element and an electrostrictive actuator; Fig. 8 a schematic representation of an electrostrictive component of an electrostrictive actuator to illustrate a lateral deformation of the electrostrictive component or the electrostrictive actuator; Fig. 9 an exemplary representation of an electrostrictive actuator with a plurality of electrostrictive components; and Fig. 10 a basic representation of an optical device comprising an optical element, an electrostrictive actuator, temperature sensors, a measuring device, a control device and a compensation device.

[0115] Fig. Figure 1 shows an exemplary basic structure of an EUV projection exposure system 400 for semiconductor lithography, for which the invention can be applied. An illumination system 401 of the projection exposure system 400 comprises, in addition to a radiation source 402, an optic 403 for illuminating an object field 404 in an object plane 405. A reticle 406 arranged in the object field 404, which is held by a reticle holder 407 (shown schematically), is illuminated. A projection lens 408 (shown only schematically) serves to image the object field 404 onto an image field 409 in an image plane 410. The image projected onto a structure on the reticle 406 is onto a photosensitive layer of a wafer 411 arranged in the area of ​​the image field 409 in the image plane 410, which is held by a wafer holder 412 (also shown partially).The radiation source 402 can emit EUV radiation 413, particularly in the range between 5 nanometers and 30 nanometers. Optically different and mechanically adjustable optical elements 415, 416, 418, 419, 420 are used to control the radiation path of the EUV radiation 413. The optical elements are located in the Fig. 1 EUV projection exposure system 400 shown as adjustable mirrors in suitable embodiments mentioned below only as examples.

[0116] The EUV radiation 413 generated by the radiation source 402 is aligned by means of a collector integrated in the radiation source 402 such that the EUV radiation 413 passes through an intermediate focus in the region of an intermediate focus plane 414 before striking a field facet mirror 415. After the field facet mirror 415, the EUV radiation 413 is reflected by a pupil facet mirror 416. With the aid of the pupil facet mirror 416 and an optical assembly 417 with mirrors 418, 419, 420, field facets of the field facet mirror 415 are imaged into the object field 404.

[0117] In Fig. Figure 2 shows an exemplary DUV projection exposure system 100. The projection exposure system 100 comprises an illumination system 103, a device called a reticule stage 104 for receiving and precisely positioning a reticule 105, by which the subsequent structures on a wafer 102 are determined, a wafer holder 106 for holding, moving and precisely positioning the wafer 102 and an imaging device, namely a projection lens 107, with several optical elements 108, which are held in a lens housing 140 of the projection lens 107 via mounts 109.

[0118] The optical elements 108 can be designed as individual refractive, diffractive and / or reflective optical elements 108, such as lenses, mirrors, prisms, end plates and the like.

[0119] The basic operating principle of the projection exposure system 100 provides that the structures introduced into the reticule 105 are mapped onto the wafer 102.

[0120] The illumination system 103 provides a projection beam 111 in the form of electromagnetic radiation, which is required for imaging the reticulum 105 onto the wafer 102. A laser, a plasma source, or the like can be used as the source of this radiation. In the illumination system 103, the radiation is shaped by optical elements such that the projection beam 111, upon striking the reticulum 105, exhibits the desired properties with regard to diameter, polarization, wavefront shape, and the like.

[0121] Using the projection beam 111, an image of the reticulum 105 is generated and transferred, appropriately reduced in size, to the wafer 102 by the projection lens 107. The reticulum 105 and the wafer 102 can be moved synchronously, so that areas of the reticulum 105 are mapped onto corresponding areas of the wafer 102 practically continuously during a so-called scan process.

[0122] In Fig. Figure 3 shows a third projection lens 200 in development as an immersion lithographic DUV projection exposure system. For further background information on such a projection lens 200, reference is made, for example, to WO 2005 / 069055 A2, the corresponding content of which is incorporated into the present description by reference; therefore, the exact operating principle is not discussed in detail here.

[0123] It is recognizable as being comparable to the DUV projection exposure system 100 according to Fig. 2, a reticle stage 104, by which the subsequent structures on the wafer 102, which is arranged on the wafer holder 106 or wafer table, are determined. The projection lens 200 of the Fig. 3 also features several optical elements, in particular lenses 108 and mirrors 201.

[0124] However, within the scope of the invention, the reticule 105, 406, the reticule stage 104 or the reticule holder 407, the wafer 102, 411, the wafer holder 106, 412 or other elements in the area of ​​the beam path of the projection exposure system 100, 400 or the projection lens 200 can also be referred to as optical elements.

[0125] To correct imaging errors in a projection exposure system, for example, projection exposure systems 100, 400 or projection lens 200, targeted deformation of their optical elements 108, 201, 415, 416, 418, 419, 420 can be suitable. Imaging errors in an EUV projection exposure system 400 can be corrected particularly efficiently by selectively deforming one or more mirrors of the projection lens 408.

[0126] Within the beam path of the projection lens 200, two mirrors 201 are provided, between which an intermediate focal plane 414 is located.

[0127] Although the invention is fundamentally suitable for correcting imaging errors by deforming any optical elements of any projection lens, it can be used particularly advantageously for deforming optical elements 201, 415 adjacent to an intermediate focus plane 414. Accordingly, the mirrors 201 of the immersion lithographic projection lens of the Fig. 3 according to the invention, be designed to be deformable.

[0128] The use of the invention is not limited to use in projection exposure systems 100, 400 or in a projection lens 200, in particular not with the described setup.

[0129] Furthermore, the invention and the following embodiment are not to be understood as being limited to a specific design. The following figures merely illustrate the invention in an exemplary and highly schematic way.

[0130] The Fig. 4 to 7 and the Fig. Figure 10 shows an optical device 1 with an optical element 2 and an electrostrictive actuator 3. The optical device 1 can be part of a projection exposure system 100, 400 or a projection lens 200 for semiconductor lithography, in particular part of an EUV projection exposure system 400 or an immersion lithographic DUV projection exposure system 200.

[0131] The optical element 2 can be, in particular, a lens or a mirror. Preferably, the optical element 2 is an adaptive optical element, in particular a deformable lens or a deformable mirror, especially of projection exposure systems 100, 400 or a projection lens 200, preferably an EUV projection exposure system 400 or an immersion lithographic DUV projection lens 200. Particularly preferably, the optical element 2 is configured as a mirror 201 of the immersion lithographic DUV projection lens 200 or as a mirror 415, 416, 418, 419, 420 of the EUV projection exposure system 400. Most preferably, the optical element 2 is arranged between the reticle 105, 406 and the wafer 102, 411.The optical element 2 is particularly preferably designed as one of the mirrors of the projection lens 408 of the EUV projection exposure system 400, as lens 108 of the DUV projection exposure system 100 or as lens 201 of the immersion lithographic DUV projection lens 200.

[0132] The optical element 2 according to the invention can also be designed as a lens 108 of a DUV projection exposure system 100 or of an immersion lithographic DUV projection lens 200.

[0133] The optical device 1 is preferably part of a device for correcting imaging errors of a projection exposure system 100, 400 or a projection lens 200 and the optical element 1 is designed as a lens or mirror of the projection exposure system 100, 400 or the projection lens 200.

[0134] The optical device 1 with the optical element 2 is described in more detail in the exemplary embodiments using a lens, in particular a mirror, especially for a projection exposure system, but this is not the only possible application. The optical device can be any optical device 1 with any optical element 2. The exemplary embodiments are to be understood accordingly.

[0135] The electrostrictive actuator 3 is designed such that it can be deformed by applying a control voltage. The electrostrictive actuator 3 is functionally connected to the optical element 2 in order to influence the surface shape of an optically active surface 2a of the optical element 2.

[0136] A control unit 4 is provided to supply the electro-strictive actuator 3 with the control voltage. The control unit 4 is in Fig. 10 schematically represented.

[0137] A measuring device 5 is provided, which is configured to directly and / or indirectly measure the temperature and / or any temperature changes of the electrostrictive actuator and / or its surroundings, at least temporarily, while the electrostrictive actuator 3 is influencing the optically effective surface 2a of the optical element 2. Based on the data or measured quantities, a temperature-dependent influence on the control of the electrostrictive actuator 3 can then be taken into account.

[0138] The control unit 4 is set up to adjust a desired deformation of the optically effective surface 2a, taking into account the data of the measuring unit 5, and to control the electrostrictive actuator accordingly.

[0139] The measuring device 5 is shown schematically in the Fig. 10 shown.

[0140] In the exemplary embodiments, it is provided that the measuring device 5 measures at least one of the following quantities, - the temperature and / or the temperature change of the electrostrictive actuator 3 and / or - the temperature and / or the temperature change in the environment of the electrostrictive actuator 3 and / or - temperature-dependent properties of the electrostrictive actuator, and / or - the change in the surface shape of at least one of the surfaces 2a of the optical element 2 when a specific electrical voltage is applied to the electrostrictive actuator 3, in order to detect and, if necessary, correct a sensor deviation of the temperature sensors by measuring the surface shape through a comparison with known setpoints (for example, from a lookup table, etc.).

[0141] The measurement of the temperature and / or temperature change in the vicinity of the electrostrictive actuator means that the measurement is taken so close to the electrostrictive actuator that the measured temperature or temperature change still allows conclusions to be drawn about the temperature or temperature change of the electrostrictive actuator, for example through simulations or previously calculated tables.

[0142] Preferably, the measuring device 5 is configured to measure continuously during the operation of the electrostrictive actuator 3. The measurement can also be performed during operational breaks of the projection exposure system 100, 400 or the projection lens 200, such as when changing the semiconductor substrate, in particular the wafer 411, 102 or the mask of the projection exposure system 100, 400.

[0143] It can also be provided that the measuring device 5 only measures temporarily, while the electrostrictive actuator 3 influences the optically effective surface 2a of the optical element 2.

[0144] In the exemplary embodiments, it is provided that the measuring device 5 measures or determines a temperature distribution of the electrostrictive actuator 3, for which purpose the measuring device 5 is set up accordingly and a corresponding number of measuring points are provided.

[0145] In the exemplary embodiments, the electrostrictive actuator 3 is designed such that the application of an electrical voltage leads to a lateral deformation of the electrostrictive actuator 3 in the plane of the electrostrictive actuator 3.

[0146] The control unit 4 is set up to adjust a value for an m31 or d31 coefficient characterizing the electrostrictive transverse effect for controlling the electrostrictive actuator 3, based on the data determined by the measuring unit 5, in order to take into account the temperature-dependent influence.

[0147] The m31 or d31 coefficient, or its effect (lateral deformation) on the electrostrictive actuator, is in principle in the Fig. 7 and Fig. 8 shown. In the Fig. Figure 7 also shows an m33 or d33 coefficient, but this is only for the sake of completeness. In the exemplary embodiments, it is intended that the m31 or d31 coefficient, rather than the m33 or d33 coefficient, is taken into account.

[0148] The control unit 5 is designed to take into account thermal changes in material parameters within the electrostrictive actuator 3 and / or components in the vicinity of the electrostrictive actuator 3.

[0149] As in the Fig. 4 to 7 and the Fig. As shown in Figure 10, the electrostrictive actuator 3 can preferably be attached to the optical element 2 by means of an adhesive 6. Other attachment methods are also possible, in particular a soldered connection; however, attachment by means of an adhesive 6 or an adhesive layer has proven to be particularly suitable. The optical element is part of a projection lens, which is part of a projection exposure system.

[0150] In the exemplary embodiments, the electrostrictive actuator 3 is arranged on a rear side 2b of the optical element 2 facing away from the optically effective surface 2a.

[0151] Alternatively and / or additionally, the electrostrictive actuator 3 can also be arranged on the optically effective surface 2a of the optical element outside a light area or on a side surface of the optical element 2 (neither is shown).

[0152] The electrostrictive actuator 3 can extend over a section or a partial area of ​​the back surface 2b of the optical element 2, or even over the entire back surface 2b of the optical element 2. It is also possible to use several electrostrictive actuators 3, each distributed over a partial area, preferably a partial area, of the back surface 2b of the optical element 2.

[0153] Within the framework of the solution according to the invention, it can also be provided that the electrostrictive actuator 3 influences only a section of the optically effective surface 2a of the optical element 2.

[0154] In the exemplary embodiments, the control unit 4 is configured to take into account the thermal change in stiffness and the thermal expansion of the adhesive 6 when controlling the electrostrictive actuator 3. The control of the electrostrictive actuator 3 can thus be carried out considering the effect of temperature changes in the adhesive 6, so that the effects of temperature changes in the adhesive 6 on the optically effective surface 2a of the optical element 2 are taken into account when controlling the electrostrictive actuator 3. Similarly, a thermally induced change in the expansion or stiffness of a soldered joint and / or the substrate of the optical element can also be taken into account.

[0155] In the exemplary embodiment, the electrostrictive actuator 3 is provided to have a plurality of electrostrictive components 7. This is exemplified in the Fig. 4 to 7, the Fig. 10 and especially the Fig. Figure 9 shows the electrostrictive actuator 3, preferably designed as an electrostrictive mat. One or more actuators 3 can be mounted beneath the mirror substrate. The actuators 3 can also be grouped into one or more units. The distribution of the electrostrictive components 7 of the electrostrictive actuator 3, particularly in a mat embodiment, is preferably regular, as illustrated in Figure 9. Fig. 9 is an example of this, but not a limiting one.

[0156] According to the invention, the measuring device 5 can be provided to measure temperature-dependent properties of the electrostrictive actuator 3, in particular a capacitance and / or an electrical resistance and / or a frequency-dependent impedance of the electrostrictive actuator.

[0157] In the exemplary embodiment, the measuring device 5 can also include an infrared camera for temperature detection and / or an electrical bridge circuit for measuring temperature-dependent properties of the electrostrictive actuator 3. While the aforementioned variants are not shown in the exemplary embodiments, they are feasible for a person skilled in the art. The aforementioned measuring methods can be used alternatively or in addition to one another.

[0158] In the exemplary embodiment, as in the Fig. 4 to 7 and in the Fig. Figure 10 shows that the measuring device comprises 5 temperature sensors 8 which measure the temperature and / or the temperature change and / or the temperature distribution of the electrostrictive actuator and / or its environment.

[0159] According to the invention, it can be provided that each electrostrictive component 7 or a group of electrostrictive components is assigned a temperature sensor 8. In the Fig. 4, Fig. 5 and Fig. Figure 6 shows one temperature sensor 8 as an example; however, several temperature sensors 8 may also be provided, in particular, each of the electrostrictive components 7 may be assigned a temperature sensor 8.

[0160] In the embodiment according to the Fig. 4 and Fig. Figure 5 provides that the temperature sensors are arranged on a rear side 3a of the electrostrictive actuator 3 facing away from the optical element 2. In the exemplary embodiment, the temperature sensor 8 is specifically located on the rear side 3a of one of the electrostrictive components 7 of the electrostrictive actuator 3.

[0161] In the Fig. Figure 6 shows an alternative positioning. In the embodiment shown below. Fig. 6 The temperature sensor 8 is positioned on one side of the optical element 2, in the exemplary embodiment on the rear side 2b of the optical element 2 facing the electrostrictive actuator 3, between electrostrictive components 7 of the electrostrictive actuator 3. This is an alternative and / or supplementary placement of the temperature sensors 8, which can also be used in combination with the placement as shown in the Fig. 4 and Fig. 5 is shown, and can be used.

[0162] The temperature sensors 8, which are located in the Fig. The embodiment shown in 6 can be arranged between electrostrictive components 7, provided that the electrostrictive actuator 3 is designed accordingly or similarly to the one shown in Fig. The variant shown in 9 is arranged in gaps or free spaces 3b of the electrostrictive actuator 3.

[0163] The temperature sensors 8 can be configured to enable resistance-based measurement, in particular by having a material whose resistance measurably varies with temperature. Preferably, the temperature sensors 8 are configured to reliably detect temperature changes of 0.1 K, more preferably 0.03 K, and more preferably 0.01 K.

[0164] In the exemplary embodiments, it is provided that supply lines 9, to supply the electrostrictive actuator 3 or its electrostrictive components 7 with the control voltage, and supply lines 10, to supply the temperature sensors 8 with an operating voltage for measurement, are at least partially routed together or combined into a single conductor track.

[0165] In the exemplary embodiments, it can be provided that the control device 4 determines an expected wavefront effect based on the data of the measuring device 5 by the change in surface shape and / or a change in refractive index, and takes the wavefront effect into account when controlling the electrostrictive actuator 3 and / or at least one compensation means 11.

[0166] A compensatory means 11 is schematically represented in the Fig. 10 shown.

[0167] The compensation means 11 can be designed, in a manner not shown in detail, as elements that can be displaced in the direction of light or perpendicular to it, and / or as elements rotatable about the direction of light or about axes perpendicular to it, and / or as deformable elements, and / or as locally heated elements, and / or as locally cooled elements, and / or as elements that can be displaced relative to each other, preferably as aspherized plates, and / or as interchangeable elements.

[0168] In the Fig. Figure 10 schematically illustrates that the data from the temperature sensors 8 (or the data from another measuring method or other measuring points) are acquired by the measuring device 5 and made available to the control unit 4. The control unit 4 can then control the electrostrictive actuator 3, in particular by providing a value for an m31 or d31 coefficient characterizing the electrostrictive transverse effect for controlling the electrostrictive actuator 3, taking temperature-dependent influences into account. Alternatively or additionally, as shown in Fig. Figure 10 also shows that the data from the control unit 4 are used to appropriately control a compensation device 11 for low aberrations, so that the temperature-dependent influences can be taken into account accordingly. In the Fig. Figure 8 shows an example of a lateral deformation of the electrostrictive actuator 3 corresponding to the m31 or d31 coefficient. The dashed line in Fig. Figure 8 shows the state of the electrostrictive actuator 3 or an electrostrictive component 7 in a top view, for example, of the back side 3a, after a voltage has been applied. The solid line then shows the state of the electrostrictive actuator 3 or the electrostrictive component 7 before the voltage was applied.

[0169] The Fig. Figure 4 shows an advantageous setup of the optical device 1, to which the solution according to the invention is not limited.

[0170] As already shown, the optical element 2 is preferably connected to the back side 2b of the optical element 2 via an adhesive 6 or an adhesive layer; this is also shown enlarged in Fig. 5 and Fig. 6 shown accordingly.

[0171] In the exemplary embodiment, the electrostrictive actuator 3 is composed of a plurality of electrostrictive components 7. The electrostrictive actuator 3 can be designed as an electrostrictive mat.

[0172] The electrostrictive actuator 3, or its electrostrictive components 7, are supplied with voltage via supply lines 9 or an electrical contact. The supply line 9 may lead directly to the electrostrictive components 7. Alternatively, for direct contact of the electrostrictive components 7, an electrical contact or an electrically conductive layer may be formed on their rear surface 3a, which in turn contacts electrical supply lines, as shown in Fig. 5 and Fig. 6 shown.

[0173] On the rear side 3a of the electrostrictive actuator 3 or its electrostrictive components 7, in the embodiments according to the Fig. 4 to 6 an additional insulating layer 12 is provided, which at least partially shields the electrical contact or the electrically conductive layer 9 from the outside.

[0174] In Fig. Figure 5 shows an arrangement of the temperature sensors 8 on the rear side 3a of the electrostrictive actuator 3. The power supply is provided by supply lines 10, which are at least partially shared with the supply lines 9.

[0175] The Fig. Figure 6 shows an alternative representation in which the temperature sensors 8 are arranged in gaps or spaces 3b between electrostrictive components 7 on the back 2b of the optical element 2.

[0176] There are also mixtures of the Fig. 5 and Fig. 6 possible, in particular it may be provided that more temperature sensors 8 are used, in particular that each of the electrostrictive components 7 or a group of electrostrictive components 7 is assigned a temperature sensor 8.

[0177] As in the Fig. 5 and Fig. As shown in Figure 6, the temperature sensors 8 can preferably be attached to the rear side 2b of the optical element 2 or to the rear side 3a of the electrostrictive actuator 3 or its electrostrictive components 7 by means of an adhesive layer 6a. The thermal change in stiffness and / or the thermal expansion of the adhesive 6a and / or other components involved during the actuation of the electrostrictive actuator can optionally also be taken into account during the actuation of the electrostrictive actuator. This can be advantageous for drift reduction or drift correction.

[0178] The present embodiment also serves to illustrate an optical element 2 for use in an optical device 1, as described in claim 20.

[0179] The present embodiment also serves to illustrate a method for influencing the surface shape of an optically effective surface 2a of an optical element 2, according to which, at least partially, while the electrostrictive actuator 3 influences the optically effective surface 2a of the optical element 2, the temperature and / or a temperature change and / or a temperature distribution of the electrostrictive actuator 3 and / or its surroundings is directly measured and / or indirectly determined in order to take into account a temperature-dependent influence on the control of the electrostrictive actuator 3. Preferably, the aforementioned measurement is carried out at least temporarily while the actuator 3 is actively influencing the surface 2a of the optical element 2, i.e., while an electrical voltage is applied to the actuator 3.From the measured data, a parasitic effect on the surface shape of the optically effective surface 2a and / or a change in the refractive index of the optical element 2 can then be determined.

Claims

[1] Projection exposure system (400, 100) comprising a projection lens (408, 107, 200) wherein the projection lens (408, 107, 200) comprises an optical device (1), wherein the optical device (1) comprises an optical element (2) with an optically effective surface (2a) and at least one electrostrictive actuator (3) which is deformable by applying a control voltage, wherein the electrostrictive actuator (3) is functionally connected to the optical element (2) in order to influence the surface shape of the optically effective surface (2a), wherein a control device (4) is provided to supply the electrostrictive actuator (3) with the control voltage, and wherein a measuring device (5) is provided. characterized by, that the measuring device (5) is configured to directly measure and / or indirectly determine the temperature and / or a temperature change of the electrostrictive actuator (3) and / or its environment, at least temporarily, while the electrostrictive actuator (3) influences the optically effective surface (2a) of the optical element (2), in order to take into account a temperature-dependent influence when the electrostrictive actuator (3) is controlled by the control device (4), wherein the measuring device (5) comprises temperature sensors (8) that measure the temperature and / or the temperature change and / or the temperature distribution of the electrostrictive actuator (3) and / or its environment, and wherein the temperature sensors (8) are arranged on a rear side (3a) of the electrostrictive actuator (3) facing away from the optical element (2). [2] Projection exposure system (400,100) according to claim 1, characterized by, that the measuring device (5) measures at least one of the following quantities in order to indirectly determine the temperature and / or the temperature change, - temperature-dependent properties of the electrostrictive actuator (3), and / or - the change in the surface shape of at least one of the surfaces (2a, 2b) of the optical element (2) when a specific control voltage is applied to the electrostrictive actuator (3). [3] Projection exposure system (400,100) according to claim 1 or 2, characterized by , that the measuring device (5) continuously measures or determines the temperature and / or the temperature change during the operation of the electrostrictive actuator (3). [4] Projection exposure system (400,100) according to claim 1, 2 or 3, characterized by, that the electrostrictive actuator (3) is designed such that the application of a control voltage leads to a lateral deformation of the electrostrictive actuator (3) in the plane of the electrostrictive actuator (3). [5] Projection exposure system (400,100) according to one of claims 1 to 4, characterized by , that the control device (4) is set up to adjust a value for an m31 or d31 coefficient characterizing the electrostrictive transverse effect for controlling the electrostrictive actuator (3) on the basis of the data determined by the measuring device (5) in order to take into account the temperature-dependent influence. [6] Projection exposure system (400,100) according to one of claims 1 to 5, characterized by , that the control device (4) is set up to take into account thermal changes of material parameters within the electrostrictive actuator (3) and / or of components in the vicinity of the electrostrictive actuator (3). [7] Projection exposure system (400,100) according to one of claims 1 to 6, characterized by , that the electrostrictive actuator (3) is attached to the optical element (2) by means of an adhesive (6) or a soldered connection and the control device (4) is set up to take into account the thermal change in the stiffness and / or elongation of the adhesive (6) or the soldered connection when controlling the electrostrictive actuator (3). [8] Projection exposure system (400,100) according to one of claims 1 to 7, characterized by , that the electrostrictive actuator (3) is arranged on a rear side (2b) of the optical element (2) facing away from the optically effective surface (2a). [9] Projection exposure system (400,100) according to one of claims 1 to 8, characterized by, that the electrostrictive actuator (3) is arranged on the optically effective surface (2a) of the optical element (2) outside of a light area or on a side surface of the optical element. [10] Projection exposure system (400,100) according to one of claims 1 to 9, characterized by , that the electrostrictive actuator (3) has a plurality of electrostrictive components (7). [11] Projection exposure system (400,100) according to one of claims 1 to 10, characterized by , that the measuring device (5) measures a capacitance and / or an electrical resistance and / or a frequency-dependent impedance of the electrostrictive actuator (3) in order to determine the temperature and / or the temperature change. [12] Projection exposure system (400,100) according to one of claims 1 to 11, characterized by, that the measuring device (5) includes an infrared camera for temperature detection and / or an electrical bridge circuit for measuring temperature-dependent properties of the electrostrictive actuator (3). [13] Projection exposure system (400,100) according to one of claims 1 to 12, characterized by , that the temperature sensors (8) are arranged on one side (2b) of the optical element (2) between electrostrictive components (7) of the electrostrictive actuator (3). [14] Projection exposure system (400,100) according to one of claims 1 to 13, characterized by , that the temperature sensors (8) are configured to measure a temperature change of 0.1 K and greater, preferably of 0.03 K and greater, more preferably of 0.01 K and greater. [15] Projection exposure system (400,100) according to one of claims 1 to 14, characterized by, that supply lines (9) to supply the electrostrictive actuator (3) with the control voltage and supply lines (10) to supply the temperature sensors (8) with operating voltage are at least partially run together and / or are functionally and / or physically combined into a single conductor path and / or are identical. [16] Projection exposure system (400,100) according to one of claims 1 to 15, characterized by , that the control device (4) determines an expected wavefront effect based on the data from the measuring device (5) by changing the surface shape and / or the refractive index, and takes the wavefront effect into account when controlling the electrostrictive actuator (3) and / or at least one compensation means (11). [17] Projection exposure system (400,100) according to claim 16, characterized by, that the compensation means (11) are designed as elements that can be displaced in the direction of light or perpendicular to it and / or as elements that can be rotated about the direction of light or about axes perpendicular to it and / or as deformable elements and / or as locally heated elements and / or as locally cooled elements and / or as elements that can be displaced from one another, preferably as aspherized plates, and / or as interchangeable elements. [18] Projection exposure system (400,100) according to one of claims 1 to 17, characterized by , that the optical element (2) is a mirror, in particular a locally deformable mirror. [19] Method for correcting temperature influences in a projection exposure system (400, 100) according to one of claims 1 to 18, by influencing the surface shape of an optically effective surface (2a) of an optical element (2) which is arranged in the projection exposure system (400, 11), wherein the optical element (2) is functionally connected to an electrostrictive actuator (3), wherein the electrostrictive actuator (3), when supplied with a control voltage, is suitable to influence the surface shape of the optically effective surface (2a), characterized by, that at least temporarily, while the electrostrictive actuator (3) influences the optically effective surface (2a) of the optical element (2), the temperature and / or a temperature change of the electrostrictive actuator (3) and / or its environment is directly measured and / or indirectly determined in order to take into account a temperature-dependent influence on the control of the electrostrictive actuator (3). [20] Method according to claim 19, characterized by , that from the measured data a parasitic effect on the surface shape of the optically effective surface (2a) and / or a change in the refractive index of the optical element (2) is determined. [21] Method according to claim 19 or 20, characterized by, that the application of the control voltage leads to a lateral deformation of the electrostrictive actuator (3) in the plane of the electrostrictive actuator (3), and the measured data are used to adjust a value for an m31 or d31 coefficient characterizing the electrostrictive transverse effect for the control of the electrostrictive actuator (3) in such a way that temperature-dependent influences are taken into account. [22] Method according to claim 21, characterized by , that the change in surface shape of at least one of the surfaces (2a, 2b) of the optical element (2), in particular the optically effective surface (2a), is determined when a specific control voltage is applied to the electrostrictive actuator (3), in particular by measurable aberrations, and the m31 or d31 coefficient is determined from this. [23] Method according to one of claims 21 or 22, characterized by, that at least one temperature-dependent parameter of the electrostrictive actuator (3), in particular a capacitance and / or an electrical resistance and / or a frequency-dependent impedance, is determined and the m31 or d31 coefficient of the electrostrictive actuator (3) is determined from this. [24] Method according to any one of claims 21 to 23, characterized by , that the method for correcting imaging errors of a projection lens (107, 403, 200), wherein the projection lens (107, 403, 200) is part of a projection exposure system (400, 100), is used.

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