Adaptive optical module for microlithographic projection exposure apparatus

Abstract

The invention provides an adaptive optical module (38A) for a microlithographic projection exposure apparatus (10; 210), comprising: an optical surface (32) for interacting with exposure radiation (14) of the projection exposure apparatus; and a plurality of actuators (36n-1, 36n, 36n + 1) for changing the shape of the optical surface. The adaptive optical module has a dielectric (48) deformable by application of a voltage (68), and each actuator comprises a separate control electrode (62n-1, 62n, 62n + 1), each control electrode being arranged to generate a respective electric field in one layer of the dielectric. The control electrodes are connected to one another by means of a weakly electrically conductive structure (60) having an electrical conductivity of at least 0.1 mS / m, and in order to measure the impedance (86n-1, 86n, 86n + 1) of at least one actuator, a measuring electrode (58n-1, 58n, 58n + 1) is arranged between the control electrode of the measured actuator and the dielectric.

Description

[0001] This application claims priority to German patent application 10 2023 210 952.2 dated November 3, 2023. The entire disclosure of that patent application is incorporated herein by reference. Background of the Invention

[0003] The present invention relates to an adaptive optics module for a microlithography projection exposure apparatus having a plurality of actuators, a projection exposure apparatus for microlithography having such an adaptive optics module, and a method for determining the corresponding deflection of the plurality of actuators of the adaptive optics module of the microlithography projection exposure apparatus.

[0004] To image the mask structure onto the wafer with the highest possible accuracy, the projection lenses of the projection exposure equipment used in microlithography need to have the smallest possible wavefront aberrations. Therefore, the projection lenses are equipped with manipulators that can correct wavefront errors by changing the state of the individual optical elements of the projection lens. Examples of such state changes include positional changes in one or more of the six rigid body degrees of freedom of the optical elements involved, as well as deformation of the optical elements.

[0005] For the latter state change, the optical element is typically integrated into an adaptive optics module of the type described above. This adaptive optics module may have one or more piezoelectric or electrostrictive actuators for actuating the optical surface. The operating principle of such actuators is based on deforming a dielectric by applying an electric field. Typically, to determine the desired state change, the aberration characteristics of the projection lens are measured periodically, and, if necessary, the changes in aberration characteristics between measurements are determined through simulation. For example, the heating effect of the lens or mirror can be accounted for through calculation.

[0006] When using piezoelectric or electrostrictive adaptive optics, the problem often lies in the fact that changes in relevant parameters of the actuator material, such as those caused by temperature variations, aging, defects, or drift, can lead to significant inaccuracies in surface shape correction performed by the adaptive optics.

[0007] To correct for or avoid these inaccuracies, for example, as proposed in DE 10 2020 212 743 A1, measuring electrodes for temperature measurement are arranged in the actuator material, and corresponding corrections are performed based on the measurement results. However, this involves indirect measurement of surface shape errors caused by actuator deviations, which is generally not accurate enough.

[0008] The task on which it is based

[0009] The objective of this invention is to provide an adaptive optics module and method of the type described at the beginning, which can solve the aforementioned problems, and in particular, can perform surface shape correction of adaptive optics elements with improved accuracy.

[0010] Solution according to the invention

[0011] The aforementioned task can be accomplished, for example, by an adaptive optics module for a microlithography projection exposure apparatus according to a first aspect of the invention. This adaptive optics module includes an optical surface for interacting with the exposure radiation of the projection exposure apparatus and a plurality of actuators for changing the shape of the optical surface. Furthermore, the adaptive optics module has a dielectric material capable of being deformed by applying a voltage, and each actuator includes a separate control electrode, each control electrode being arranged to generate a corresponding electric field in a layer of the dielectric. Moreover, these control electrodes are interconnected by a weakly conductive structure having a conductivity of at least 0.1 mS / m, i.e., 10⁻⁻⁶. 4 The conductivity is S / m, and in order to measure impedance, a measuring electrode is arranged between the control electrode of the actuator being measured (i.e., the actuator with respect to its impedance) and the dielectric. The actuator being measured should be understood as the actuator with respect to impedance.

[0012] According to one embodiment, a corresponding measuring electrode is arranged between the corresponding control electrode and the dielectric for measuring the impedance of the corresponding actuator. A weakly conductive structure should be understood as a structure with weak conductivity. According to one embodiment, the conductivity of the weakly conductive structure can be at least 0.1 mS / m (i.e., 0.0001 Siemens / m) and less than 1 kS / m. According to other embodiments, the conductivity of the weakly conductive structure is at least 1 mS / m, at least 0.01 S / m, at least 0.1 S / m, or at least 10 S / m. According to different embodiments, the upper limit of the conductivity of the weakly conductive structure can be 1 kS / m, 200 S / m, or 100 S / m.

[0013] Weakly conductive structures, for example, are constructed as layers, through which these actuators are electrically coupled. In other words, these actuators can be used in this way in a coupled network to smooth out the deformation effects when a single actuator is controlled. By using weakly conductive structures, a gradient field appears between the electrodes of the actuators. The statement that each actuator has a separate control electrode should be understood as meaning that each actuator has its own control electrode, i.e., the actuators do not share a single control electrode.

[0014] An electric field is generated within the layer of a dielectric by applying a voltage to it. This causes deformation of the dielectric. Corresponding measuring electrodes are arranged to measure the impedance of the corresponding actuator, i.e., the impedance of the actuator associated with the corresponding control electrode. This impedance can be measured during operation of the projection exposure equipment or during exposure intervals.

[0015] The solution according to the first aspect of the invention enables the determination of the deflection of at least one actuator at at least one operating point based on impedance measurements, i.e., electrical measurements on an adaptive optics module. Compared to, for example, interferometric measurements that depend on the surface shape and operating voltage, the electrical measurements according to the invention can be performed at a high repetition rate and, if necessary, during exposure operation of a microlithography projection exposure apparatus.

[0016] The solution according to the invention is also based on the understanding that when impedance measurement is performed using the control electrode of the actuator to be measured, the measurement results may be distorted because the control electrode is connected to the control electrode of an adjacent actuator through a weakly conductive structure. These distortions may be caused by leakage current between the control electrodes that occurs during impedance measurement. To eliminate this source of error, according to the first aspect of the invention, at least one measuring electrode is arranged between the control electrode of the actuator to be measured and the dielectric. This measuring electrode is not electrically connected to the electrodes of adjacent actuators, particularly to one control electrode or another measuring electrode of an adjacent actuator. Therefore, the adaptive optics module configured according to the first aspect of the invention enables the measurement of the deflection of at least one actuator with high repeatability and high accuracy. This allows for high-precision surface shape correction of the adaptive optics element. In this document, "adjacent actuators" of the reference actuator should be understood as each actuator whose control electrode is connected to the control electrode of the reference actuator through a weakly conductive layer. Therefore, the term "adjacent actuator" includes both actuators directly adjacent to the reference actuator (i.e., actuators directly adjacent to the reference actuator) and actuators one or more further away.

[0017] According to one embodiment, the weakly conductive structure is configured as a layer disposed between the control electrode of the actuator and the dielectric.

[0018] According to another embodiment, a layer composed of a weakly conductive structure extends continuously along the control electrode of the actuator.

[0019] According to another embodiment, the adaptive optics module further includes at least one base electrode arranged as a counter electrode relative to the control electrode and configured to generate a corresponding electric field in the dielectric together with the respective control electrode. Here, a common base electrode or multiple base electrodes can be provided for different actuators.

[0020] The aforementioned task can be solved, for example, by an adaptive optics module for a microlithography projection exposure apparatus according to a second aspect of the invention. This adaptive optics module includes an optical surface for interacting with the exposure radiation of the projection exposure apparatus and a plurality of actuators for changing the shape of the optical surface. Furthermore, the adaptive optics module has a deformable dielectric material that can be deformed by applying a voltage, and each actuator includes a separate control electrode, each control electrode being arranged to generate an electric field in a layer of the dielectric. Moreover, these control electrodes are interconnected by a weakly conductive structure with a conductivity of at least 0.1 mS / m. Furthermore, the adaptive optics module has an evaluation device configured to, when measuring the impedance of at least one actuator, subtract from the measurement results the effect of current flow between the control electrode of the measured actuator and at least one other control electrode caused by the weakly conductive structure on the measurement results.

[0021] The additional control electrode is preferably a control electrode directly adjacent to the control electrode being measured. According to one embodiment, for each actuator impedance measured, based on at least one predetermined coupling resistance between the control electrodes, the relevant current flow between the control electrode of the actuator being measured and at least one additional control electrode is subtracted from the measurement result. The current flow between the control electrodes is substantially or entirely through a weakly conductive structure.

[0022] According to one embodiment, a corresponding measuring electrode is arranged between the corresponding control electrode and the dielectric for measuring the impedance of the corresponding actuator. A weakly conductive structure should be understood as a structure with weak conductivity. According to one embodiment, the conductivity of the weakly conductive structure can be at least 0.1 mS / m (i.e., 0.0001 Siemens / m) and less than 1 kS / m. According to other embodiments, the conductivity of the weakly conductive structure is at least 1 mS / m, at least 0.01 S / m, at least 0.1 S / m, or at least 10 S / m. According to different embodiments, the upper limit of the conductivity of the weakly conductive structure can be 1 kS / m, 200 S / m, or 100 S / m.

[0023] The solution according to the second aspect of the invention, like the solution according to the first aspect of the invention, enables the determination of the deflection of at least one actuator at at least one operating point based on impedance measurement, i.e., electrical measurement on the adaptive optics module. For impedance measurement, the control electrodes of the actuator to be measured can be used. As explained above in conjunction with the solution according to the first aspect of the invention, such electrical measurement can be performed at a high repetition rate, and if necessary, can also be performed during exposure operation of the microlithography projection exposure apparatus.

[0024] The solution according to the invention is also based on the understanding that since the control electrode is electrically connected to the control electrode of an adjacent actuator through a weakly conductive structure, leakage current may cause distortion in the measurement results. According to a second aspect of the invention, these distortions are avoided by subtracting the effect of current flow caused by the weakly conductive structure between the control electrode of the measured actuator and at least one other control electrode on the measurement results. Therefore, the adaptive optics module configured according to the second aspect of the invention enables the measurement of the deflection of at least one actuator with high repeatability and high accuracy. This allows for high-precision surface shape correction of the adaptive optics element.

[0025] According to one embodiment of a second aspect of the invention, the adaptive optics module has at least one current measuring device for measuring current flow between a control electrode of the actuator being measured and the at least one additional control electrode, wherein the evaluation device is configured to subtract the effect from the measurement result based on the measured current flow.

[0026] According to another embodiment of the second aspect of the invention, the control electrode of the actuator being measured is adjacent, particularly directly adjacent, to the control electrodes of at least four, and especially at least eight, other actuators, and the adaptive optics module includes a current measuring device for measuring the corresponding current flow between the control electrode of the actuator being measured and each adjacent control electrode. Furthermore, the evaluation device is configured to subtract the corresponding effect of the measured current flow from the measurement results.

[0027] According to another embodiment of the second aspect of the invention, the weakly conductive structure has a plurality of segments, wherein one segment is disposed at the control electrode of the actuator being measured and another segment is disposed at the at least one other control electrode, and the two segments are conductively connected through the current measuring device.

[0028] According to another embodiment of the second aspect of the invention, these sections of the weakly conductive structure are electrically insulated from each other except through the connection of the current measuring device, for example through an insulating boundary line.

[0029] According to another embodiment of the second aspect of the invention, one segment of the weakly conductive structure is respectively arranged at the control electrode of the actuator being measured and at the control electrodes of all actuators directly adjacent to the actuator being measured, and the segment of the actuator being measured is conductively connected to each segment arranged at the directly adjacent actuators through a respective current measuring device.

[0030] According to another embodiment of the second aspect of the invention, the evaluation device is further configured to subtract the effect from the measurement result based on at least one predetermined coupling resistance between the control electrode of the actuator being measured and the at least one additional control electrode. According to one embodiment, the control electrode of the actuator being measured is adjacent to, and particularly at least eight other control electrodes of actuators, and the evaluation device is configured to subtract the corresponding effect of the predetermined coupling resistance between the control electrode of the actuator being measured and the adjacent control electrodes from the measurement result.

[0031] According to another embodiment of the second aspect of the invention, the adaptive optics module includes at least one current measuring device for measuring the current flow from the additional control electrode when a test voltage is applied to the control electrode of the actuator being measured.

[0032] According to another embodiment of the second aspect of the invention, the adaptive optics element has at least one voltage source connected to at least one of the control electrodes, wherein the evaluation device is configured to subtract the line resistance from the voltage source to the control electrode from the measurement result when measuring the impedance of the at least one control electrode. In general, the adaptive optics module has an impedance measuring device configured to measure the impedance of the at least one control electrode. Such an impedance measuring device may also inject current and measure voltage instead of using a voltage source.

[0033] According to another embodiment of the second aspect of the invention, the adaptive optics module includes an AC voltage source configured to apply an AC voltage of such high frequency to the at least one control electrode, in order to determine the line resistance of the at least one control electrode, that the ohmic equivalent resistance of the actuator associated with the control electrode drops to less than 10%, particularly less than 5%, of the value of the line resistance. This frequency can be, for example, at least 10 kHz, particularly at least 100 kHz or at least 500 kHz. Here, in general, the adaptive optics module may also have an impedance measuring device that injects AC current instead of an AC voltage source.

[0034] According to another embodiment of the second aspect of the invention, the adaptive optics module further includes a measuring device configured to measure the current intensity flowing from a corresponding control electrode while measuring the corresponding impedance of each actuator. When measuring the impedance, an AC voltage is applied to the corresponding control electrode, and the current intensity flowing from the corresponding control electrode is measured.

[0035] According to one embodiment of the first or second aspect of the invention, the adaptive optics module further includes an evaluation device configured to calculate actuator deflection from the measured impedance of one of the actuators. This is achieved, for example, by determining the dielectric susceptibility of the relevant actuator from the measured impedance and performing a linear mapping to determine the actuator deflection.

[0036] According to another embodiment, the adaptive optics module also includes a control unit configured to correct control variables applied to the associated control electrodes based on the calculated actuator deflection.

[0037] According to another embodiment of the first or second aspect of the invention, the weakly conductive structure comprises a rare-earth nickel oxide. Advantageously, the weakly conductive structure is at least 90% or entirely composed of the rare-earth nickel oxide. According to one embodiment, the rare-earth nickel oxide comprises LaNiO3, which may also be referred to as LNO.

[0038] Furthermore, according to the present invention, a projection exposure apparatus for microlithography is provided, the projection exposure apparatus comprising at least one adaptive optics module according to one of the embodiments or variations of the first or second aspect of the present invention.

[0039] Furthermore, according to a first aspect of the invention, a method is provided for determining the corresponding deflection of a plurality of actuators in an adaptive optics module of a microlithography projection exposure apparatus, the actuators being configured to change the shape of an optical surface of the optical module. The adaptive optics module includes a voltage-deformable dielectric, each actuator having a separate control electrode for generating a corresponding electric field in a layer of the dielectric, these control electrodes being interconnected by a weakly conductive structure with a conductivity of at least 0.1 mS / m, and the method comprising the steps of: measuring the impedance of at least one of the actuators by means of a measuring electrode arranged between the control electrode of the actuator being measured and the dielectric, and calculating the deflection of each actuator from the corresponding measured impedance.

[0040] Furthermore, according to a second aspect of the invention, a method is provided for determining the corresponding deflection of a plurality of actuators in an adaptive optics module of a microlithography projection exposure apparatus, the actuators being configured to change the shape of an optical surface of the optical module. Here, the adaptive optics module includes a voltage-deformable dielectric, each actuator having a separate control electrode for generating a corresponding electric field in a layer of the dielectric, these control electrodes being interconnected via a weakly conductive structure with a conductivity of at least 0.1 mS / m, and the method comprising the steps of: measuring the impedance of at least one of the actuators; subtracting from the impedance measurement result the effect of current flow caused by the weakly conductive structure, wherein the current flow occurs between the control electrode of the measured actuator and at least one other control electrode; and calculating the corresponding deflection of each actuator from the corresponding measured impedance.

[0041] According to one embodiment of the method of the second aspect of the invention, the current flow caused by the weakly conductive structure is measured by means of a current measuring device, and the effect is subtracted from the measurement result of the impedance measurement based on the measured current flow.

[0042] According to another embodiment of the second aspect of the invention, a coupling resistance between the control electrode of the actuator being measured and the at least one other control electrode is determined, and this effect is subtracted from the measurement result of the impedance measurement based on the determined coupling resistance. In other words, the coupling resistance is determined before subtracting this effect from the measurement result.

[0043] According to another embodiment of the second aspect of the invention, the line resistance of at least one electrical connection between at least one voltage source and at least one of the control electrodes is determined by applying an AC voltage of such high frequency to the control electrode that the ohmic equivalent resistance of the actuator associated with the control electrode drops to less than 10% of the value of the line resistance. Advantageously, the determined line resistance is subtracted from the measurement result when measuring the impedance of the control electrode.

[0044] According to another embodiment of the first or second aspect of the invention, during the operation of the projection exposure apparatus to expose the substrate, the effect of current flow caused by the weakly conductive structure is subtracted from the measurement results of the impedance measurement. In other words, this subtraction is performed over a period of time from the start of the first field exposure on the substrate (also referred to as the wafer) to the end of the last field exposure on the substrate. That is, the subtraction can be performed during the exposure of one or more fields, or during the brief exposure intervals between the exposures of these fields. Advantageously, the entire method for determining the corresponding deflections of the plurality of actuators of the adaptive optics module according to the first or second aspect of the invention is performed during the operation of the projection exposure apparatus to expose the substrate.

[0045] The features described above regarding the adaptive optics module according to the first or second aspect of the invention, including embodiments, examples, or variations thereof, can be correspondingly adapted to the method according to the first or second aspect of the invention, and vice versa. These and other features of the embodiments of the invention are set forth in the description of the drawings and the claims. Each feature can be implemented individually or in combination as an embodiment of the invention. Furthermore, they can describe advantageous embodiments that are themselves protectable, and whose protection may be claimed during or after the application is pending.

[0046] Brief description of the attached figures

[0047] The above and other advantageous features of the present invention will be described in detail below with reference to the illustrative drawings of exemplary embodiments or implementations of the invention. The drawings show:

[0048] Figure 1 An embodiment of an EUV projection exposure apparatus for microlithography is shown, which includes an adaptive optics module.

[0049] Figure 2 It shows according to Figure 1 One implementation of the adaptive optics module, which is in an initial state and a calibration state.

[0050] Figure 3 An embodiment of an adaptive optics module according to a first aspect of the invention is shown, having a cross-sectional view of an exemplary layer structure having three actuators arranged side by side and an electronic unit.

[0051] Figure 4 An embodiment of an adaptive optics module according to a second aspect of the invention is shown, having a cross-sectional view of an exemplary layer structure having three actuators arranged side-by-side and an electronic unit.

[0052] Figure 5 It shows according to Figure 4 Another cross-sectional view of the adaptive optics module, with the control electrodes of the individual actuators shown from above.

[0053] Figure 6 It shows Figure 8 The diagram shown is an equivalent circuit diagram of an actuator for one embodiment of the adaptive optics module of the second aspect of the present invention.

[0054] Figure 7 It shows according to Figure 6 The equivalent circuit diagram, in which line resistance is additionally considered.

[0055] Figure 8Another embodiment of the adaptive optics module according to a second aspect of the invention is shown, having a cross-sectional view of an exemplary layer structure having three actuators arranged side by side and an electronic unit.

[0056] Figure 9 A view of a DUV projection exposure apparatus for microlithography, featuring the adaptive optics module, is shown.

[0057] Detailed description of embodiments of the present invention

[0058] In the embodiments, implementations, or variations described below, elements that are functionally or structurally similar to each other are indicated by the same or similar reference numerals wherever possible. Therefore, in order to understand the characteristics of the various elements of a particular embodiment, reference should be made to the description of other embodiments or the general description of the invention.

[0059] For ease of description, a Cartesian xyz coordinate system is given in the accompanying drawings, from which the corresponding positional relationships of the components shown in each figure are derived. Figure 1 In the middle, the y-direction is perpendicular to the plane of the drawing when entering it, the x-direction is to the right, and the z-direction is upward.

[0060] Figure 1 An embodiment of a projection exposure apparatus 10 for microlithography according to the present invention is shown. This embodiment is designed to operate in the EUV wavelength range, i.e., using electromagnetic radiation with wavelengths less than 100 nm, particularly about 13.5 nm or about 6.8 nm. Due to this operating wavelength, all optical elements are constructed as mirrors. However, the present invention is not limited to projection exposure apparatuses in the EUV wavelength range. Other embodiments according to the present invention are designed for operating wavelengths in the UV range, such as 365 nm, 248 nm, or 193 nm. In this case, at least some optical elements are constructed as conventional transmission lenses, as described below. Figure 9 As illustrated in the example.

[0061] according to Figure 1 The projection exposure apparatus 10 includes an exposure radiation source 12 for generating exposure radiation 14. In the present case, the exposure radiation source 12 is configured as an EUV source and may include, for example, a plasma radiation source. The exposure radiation 14 first passes through an illumination optics system 16 and is guided by this illumination optics onto a mask 18.

[0062] Mask 18 has mask structures that are imaged onto a wafer-shaped substrate 24 during exposure operations of the projection exposure apparatus 10, and mask 18 is movably supported on mask shift stage 20. Substrate 24 is movably supported on substrate shift stage 26. Mask 18 can be configured as follows: Figure 1The structure shown is a reflective mask, or alternatively, particularly for UV lithography, it can be constructed as a transmissive mask. Figure 1 In this embodiment, the exposure radiation 14 is reflected at the mask 18 and then passes through the projection lens 22, which is configured to image the mask structure onto the substrate 24. The projection exposure apparatus 10 can be configured as a so-called scanner or a so-called stepper. The exposure radiation 14 is guided within the illumination optics system 16 and the projection lens 22 by means of a plurality of optical elements, in the present case, in the form of mirrors.

[0063] In the illustrated embodiment, the illumination optics system 16 includes four optical elements, which are mirror elements 30-1, 30-2, 30-3, and 30-4. The projection lens 22 also includes four optical elements, which are mirror elements 30-5, 30-6, 30-7, and 30-8. Mirror elements 30-1 to 30-8 are arranged to guide the exposure radiation 14 in the exposure beam path 28 of the projection exposure device 10.

[0064] In the illustrated embodiment, mirror element 30-5 is part of adaptive optics module 38, which may also be referred to as an adaptive optics element. The optical surface of mirror element 30-5 serves as the active optical surface 32 of adaptive optics module 38, and its shape can be actively altered to correct local shape errors. In other embodiments, one or more of mirror elements 30-1, 30-2, 30-3, 30-4, 30-5, 30-6, 30-7, and 30-8 may also be configured as part of an adaptive optics module.

[0065] Furthermore, one or more of the mirror elements 30-1, 30-2, 30-3, 30-4, 30-6, 30-7, and 30-8, or the adaptive optics module 38, can be movably supported within the projection exposure apparatus 10. For this purpose, each movably supported mirror element is equipped with a corresponding rigid body manipulator. The rigid body manipulator, for example, allows the associated mirror element to tilt and / or shift substantially parallel to the plane containing the corresponding reflective surface of the optical element. Thus, the position of one or more mirror elements can be changed to correct imaging errors in the projection exposure apparatus 10.

[0066] According to one embodiment, the projection exposure apparatus 10 includes a control device 41 for generating control signals 42 for a configured manipulation unit (such as the rigid body manipulator described above), one or more adaptive optics modules, and / or possibly other manipulators. Figure 1The transmission of control signal 42 to adaptive optics module 38 is illustrated by way of example. According to one embodiment, in order to correct the aberrations of projection lens 22, control device 41 determines control signal 42 based on wavefront deviation 46 of projection lens 22 measured by wavefront measurement device 44 using a feedforward control algorithm.

[0067] Adaptive optics module 38 Figure 2 One embodiment is shown in the figure. Figure 2 The upper part of the diagram shows the adaptive optics module 38 in its initial state, where the shape of the optical surface 32 has an initial shape, which is a planar shape. Figure 2 The lower part of the illustration shows the adaptive optics module 38 in a correction state, wherein the shape of the optical surface 32 has a modified shape, here a convex curved shape.

[0068] The adaptive optics module 38 includes a support element 34 in the form of a backplate and a mirror element 30-5. The top side of the mirror element 30-5 forms an active optical surface 32 for reflecting exposure radiation 14. A plurality of actuators 36, also referred to as manipulators, are arranged along the bottom side of the mirror element 30-5. These actuators are preferably positioned along the bottom side of the mirror element 30-5 in a two-dimensional arrangement, both in the x and y directions. Actuators 36—in Figure 2 For readability reasons, only some of these are indicated by reference numerals—connecting support element 34 to mirror elements 30-5. Actuator 36 is configured to change its extension along its longitudinal direction upon actuation. Figure 2 In this embodiment, the actuator 36 can be actuated laterally or perpendicularly to the optical surface 32. Here, the actuators 36 are each individually controlled and therefore can be actuated independently of each other. The adaptive optics module 38 can have a higher... Figure 2 Showing more or fewer actuators 36. In Figure 2 In the correction state shown in the lower part of the diagram, the actuator 36 arranged in the center is actuated to increase its length, thereby obtaining the convex curved shape of the optical surface 32.

[0069] For simplicity, the following figures exemplarily refer to three actuators 36n-1, 36n, and 36n+1 arranged side by side. Here, n represents the counting variable of the actuator. Figure 2 In the illustration shown, n=4. In other words, the illustrations of actuators 36n-1, 36n, and 36n+1 in the following figures are used to exemplarily illustrate an adaptive optics module 38 having at least three of the actuators, wherein additional actuators 36 are preferably present.

[0070] Figure 3 An embodiment 38A according to the first aspect of the invention is exemplarily shown. Figure 2 An adaptive optics element 38 is provided, having the aforementioned three actuators 36n-1, 36n, and 36n+1. The adaptive optics element 38A includes a dielectric 48 extending across the actuators 36n-1, 36n, and 36n+1, which can be deformed by an applied electric field. It can be a piezoelectric material or an electrostrictive material. For piezoelectric materials, the deformation is based on the piezoelectric effect; for electrostrictive materials, the deformation is based on the electrostrictive effect. In this document, the electrostrictive effect is understood as the portion of dielectric deformation associated with the applied electric field, where the deformation is independent of the direction of the applied electric field and, in particular, proportional to the square of the electric field. In contrast, a linear response of deformation to an electric field is referred to as the piezoelectric effect.

[0071] In the following embodiment, actuator 36 is configured as a ferroelectric actuator, wherein dielectric 48 comprises a perovskite-based ceramic and is based on the electrostrictive effect, i.e., the deformation of dielectric 48 caused by the application of an electric field is based on the electrostrictive effect. Ferroelectric actuators are particularly suitable for shape correction of active optical surfaces 32 because they have very low drift and small hysteresis.

[0072] exist Figure 3 The adaptive optics module 38A shown includes a layer structure 39A and an electronic unit 40A. The layer structure 39A includes a support element 34 in the form of a substrate, an actuator section 52 containing actuators 36n-1, 36n, and 36n+1, and a mirror element 30-5. The structure of the actuator section 52, starting from the support element 34, includes: an insulating layer 54, a base electrode 56, the aforementioned dielectric 48, a measuring electrode 58, a weakly conductive structure 60 (here in the form of an LNO layer), and a control electrode 62. The LNO layer has a conductivity of approximately 20 S / m at 30°C. Typically, the weakly conductive layer has a conductivity of at least 0.1 mS / m, particularly at least 1 mS / m, at least 0.01 S / m, at least 0.1 S / m, or at least 10 S / m, but less than 1 kS / m, particularly less than 200 S / m or less than 100 S / m. Advantageously, an insulating layer (not shown in the figures) is arranged between the measuring electrode 58 and the weakly conductive layer 60.

[0073] Each actuator 36n-1, 36n, and 36n+1 includes a separate control electrode 62. The control electrode 62 is also referred to as the upper electrode OE, with actuator 36n-1 including the upper electrode OE. n-1 (62n-1), the actuator 36n includes the upper electrode OE n (62n), actuator 36n+1 includes upper electrode OE n+1(62n+1). In the illustrated embodiment, the base electrode 56 is grounded, serves as the counter electrode to the control electrode 62, and is also constructed as continuous, i.e., monolithic, in the current embodiment. Alternatively, the base electrode 56 may be divided into multiple individual electrodes, for example, one individual electrode for each actuator 36. These individual electrodes can then be connected by wires to maintain them at the same potential. The combination of the corresponding control electrode 62 and the base electrode is used to generate an electric field in the dielectric 48 to change the extension of the individual actuators 36.

[0074] An insulating layer 54 is used to electrically insulate the base electrode 56 relative to the support element 34. For this purpose, the insulating layer can be made of, for example, CNO (CNiO3). A weakly conductive structure 60, in the form of an LNO layer, is arranged below the control electrode 62 and extends continuously along the control electrode 62. It is used to smooth the deformation effect when controlling a single actuator 36. In this case, the actuators can be said to be arranged in the form of a coupling network. When different voltages are applied to the control electrode 62, leakage current occurs between the individual control electrodes 62 due to the weakly conductive LNO layer, thus generating a gradient field. LNO stands for LaNiO3, a material with a conductivity of approximately 864 siemens / cm.

[0075] Due to the aforementioned leakage current, impedance measurements of actuators 36n-1, 36n, and 36n+1 performed on control electrode 62 will result in distortion. To avoid this, in Figure 3 In the illustrated embodiment, each actuator 36n-1, 36n, and 36n+1 further includes a measuring electrode 58n-1, 58n, or 58n+1 for measuring the impedance of the relevant actuator. The measuring electrodes 58 are respectively disposed directly below the LNO layer 60.

[0076] The mirror element 30-5 includes a multilayer arrangement 64, also referred to as a multilayer film, and a smoothing and insulating layer 65. The smoothing and insulating layer 65 is applied to the control electrode 62 of the actuator section 52 to create a smooth contact surface for the multilayer arrangement 64 and to electrically insulate the multilayer arrangement 64 relative to the control electrode 62. The top side of the multilayer arrangement 64 forms the active optical surface 32 of the adaptive optics module 38A.

[0077] Control electrodes 62n-1, 62n, and 62n+1 are respectively connected to the voltage generator 66 of the electronic unit 40A, thereby generating a controllable operating voltage 68 (represented by reference numeral 68) relative to the base electrode 56. , or In other words, the operating voltage 68 is a variable voltage value U. A DC voltage.

[0078] In addition to the voltage generator 66, the electronic unit 40A also includes a control unit 72, a measuring device 80, and an evaluation device 88A. The electronic unit 40A, or only some parts thereof, may be part of the adaptive optics module 38A as described herein, or it may be arranged outside the adaptive optics element 38A, for example, as part of the control device 41 of the projection exposure apparatus 10.

[0079] When an operating voltage 68 other than 0 V is applied, the total change in the length extension (in the z-direction) of a single actuator 36 is called the deflection S. The corresponding deflections S for actuators 36n-1, 36n, and 36n+1 are... n-1 S n or S n+1 (See also the attached figures 43n-1, 43n, and 43n+1) Visible on the top side of the multi-layered arrangement 64. Deflection S n-1 S n-1 or S n+1 This leads to a change in the morphology 32s of the optical surface 32.

[0080] Prior to the adaptive optics module 38A being put into operation, the deflection S versus the operating voltage U is optionally measured for each actuator 36n-1, 36n, and 36n+1 in so-called reference mode. A The reference characteristic curve 70 is used. In reference mode, the operating voltage U is set. A Different values, i.e., operating voltage U A The different operating points, and for each of these values, the corresponding deflection S of the optical surface 32 of the relevant actuator 36 is measured by means of a reference measurement module in the form of an interferometer. R .

[0081] In control mode 74, control unit 72 reads a target deflection magnitude S. s Target deflection slack S s (Figure 43s) is included from Figure 1 The control signal 42 issued by the control device 41 includes the deflection S n-1 S n-1 and S n+1 The target value. The information flow in control mode 74 is... Figure 3 The dashed line indicates the direction. The control unit 72 stores a conversion scheme 69 for switching from a predetermined target deflection amount S. s Determine the operating voltages , or The preset vector U A .

[0082] Conversion scheme 69 can be particularly effective through the operating voltage U of each actuator 36.A With target deflection S s The changing relationship curves are formed. Prior to the operation of the adaptive optics module 38A, these relationship curves are advantageously determined based on the reference characteristic curves 70 defined in reference mode, which give the S-values ​​of each actuator 36. R Follow U A The process of change. Alternatively, conversion scheme 69 can be determined by calibration mode 76, which is described in more detail below. During operation, conversion scheme 69 is continuously calibrated, as described in more detail below.

[0083] For the read target deflection S s The control device 41 determines the working voltage vector U according to the conversion scheme 69. A The corresponding control value is determined, thereby controlling the voltage generator 66. The operating voltage applied by the voltage generator 66 to the control electrodes 62n-1, 62n, and 62n+1... , or Actuators 36n-1, 36n, and 36n+1 deflect accordingly. Each time a new operating voltage U is set using voltage generator 66... A At specific times, or at specific time intervals, calibration mode 76 is applied to calibrate conversion scheme 69. The information flow in calibration mode 76... Figure 3 The middle part is represented by a dotted line.

[0084] In order to perform calibration mode 76, Figure 3 The embodiment of the adaptive optics element 38A shown includes the aforementioned measurement device 80, which is assigned to the actuators 36n-1, 36n, and 36n+1 shown. The measurement device 80 includes an AC voltage source 82 applied between the measurement electrodes 58n-1, 58n, and 58n+1 and the base electrode 56, respectively, for generating an AC voltage U. W The electrical measurement voltage 83 is in the form of a uniform AC voltage source 82. According to another embodiment, instead of a uniform AC voltage source 82, separate AC voltage sources can be applied to the respective measuring electrodes 58n-1, 58n, and 58n+1.

[0085] The measuring device 80 also includes a plurality of current measuring devices 84, namely, one current measuring device 84n-1, 84n, and 84n+1 for each measuring electrode 58n-1, 58n, and 58n+1, for measuring the current due to the applied AC voltage U. W The current intensity flowing into each measuring electrode 58 , as well as The measuring device 80 is based on AC voltage U. W and the measured current intensity , as well as Determine the resulting impedance Z separately. This applies to multiple operating voltages U. A This process is performed so that the determined result is the voltage-dependent impedance Z for each actuator 36n-1, 36n, and 36n+1. n-1 (U A Z n (U A ) and Z n +1 (U A (See attached figures labeled 86n-1, 86n, and 86n+1). This forms the vector Z(U). A The impedances 86n-1, 86n, and 86n+1 are transmitted to the aforementioned evaluation device 88A.

[0086] In the evaluation device 88A, the impedance Z is measured for different actuators 36n-1, 36n, and 36n+1. n-1 (U A Z n (U A ) and Z n+1 (U A Converted into the corresponding deflection characteristic curve S n-1 (U A ), S n-1 (U A ) and S n+1 (U A Deflection characteristic curve S n-1 (U A ), S n-1 (U A ) and S n+1 (U A )exist Figure 3 In the vector S(U) A (See reference numeral 90) are summarized, one of which is exemplarily shown in schematic diagram 90d. Each deflection characteristic curve S n-1 (U A ), S n-1 (U A ) and S n+1 (U A The deflection of each actuator 36n-1, 36n, and 36n+1, and the deflection of 43n-1, 43n, or 43n+1 relative to the operating voltage U are indicated. A The relationship. In other words, the evaluation device 88A is configured to calculate at least one actuator deflection from the measured impedances 86n-1, 86n, and 86n+1.

[0087] The evaluation device measures the Z-axis. n-1 (U AZ n (U A ) and Z n+1 (U A Convert to deflection characteristic curve S n-1 (U A ), S n-1 (U A ) and S n+1 (U A In addition to other algorithms known to those skilled in the art, the capacitance C of the relevant actuator 36 can be calculated from the measured impedance Z. For this purpose, each actuator 36 is represented by an equivalent circuit diagram, for example, a series circuit consisting of a capacitor and an ohmic resistor. If the capacitance change caused by small deformation Δd is ignored, the polarizability χ can be directly derived from the capacitance C. The polarization intensity P in the dielectric and the deflection S of the actuator can then be determined by the following relationship: and S ~ P 2 , where E represents the electric field strength in the dielectric.

[0088] Deflection characteristic curve S(U) A The signal is transmitted to the comparison module 91 of the control unit 72. This comparison module executes the deflection characteristic curve S(U)... A The control unit 72 compares the deflection characteristic curve 70 with the reference characteristic curve 70, and prompts a corresponding correction 92 to the conversion scheme 69 of the control unit 72 when a deviation is found. Alternatively, the control unit 72 directly uses the deflection characteristic curve S(U) to convert the deflection characteristic curve 69 to the reference characteristic curve 70. A ) Calculate conversion scheme 69. In any case, control unit 72, in control mode 74, calculates the conversion scheme based on the determined deflection characteristic curve S(U). A Determine the operating voltage U for voltage generator 66 A The control value. In other words, the control unit 72 is configured to be based on the calculated deflection characteristic curve S(U) A The actuator deflection is in the form of a ) to correct the operating voltage applied to the associated control electrodes 62n-1, 62n, and 62n+1, respectively. , or Control variables in the form of [formula missing].

[0089] Figure 4 An embodiment 38B according to a second aspect of the present invention is exemplarily shown. Figure 2 The adaptive optics element 38 has three actuators 36n-1, 36n, and 36n+1. Here, embodiment 38B includes a layer structure 39B and an electronic unit 40B. The layer structure 39B is related to... Figure 3The difference in the layer structure of implementation 38A is that the measuring electrode 58 is not provided in the actuators 36n-1, 36n and 36n+1, and the configuration of the weakly conductive structure 60 is different.

[0090] Electronic unit 40B is configured to perform impedance measurements of actuators 36n-1, 36n, and 36n+1 directly on control electrodes 62n-1, 62n, and 62n+1. The effect of current flow between adjacent control electrodes 62 caused by the weakly conductive structure 60 (i.e., the aforementioned leakage current) on the measurement results is subtracted from the measurement results of the relevant impedance measurements by electronic unit 40B. In this document, adjacent control electrodes of the reference control electrode should be understood as each control electrode connected to the reference control electrode through a weakly conductive layer. Therefore, the term "adjacent control electrode" includes both the control electrode directly adjacent to the reference control electrode, i.e., the control electrode directly adjacent to the reference control electrode, and the control electrode neighbor that is one step below or further away.

[0091] Therefore, the weakly conductive structure 60 is divided into segments respectively assigned to one of the control electrodes 62. Figure 4 The diagram shows segments 60n-1, 60n, and 60n+1. This design is also... Figure 5 The diagram is shown as a cross-section parallel to the xy plane. For example... Figure 5 As shown, in the illustrated design, the weakly conductive segments are each square in shape, with an area exceeding that of the corresponding control electrode 62, and are centered relative to the respective control electrode 62. Thus, segments 60n-1, 60n, and 60n+1 are respectively positioned relative to the control electrode OE. n-1 (See attached diagram 62n-1), OE n or OE n+1 Centered. Similarly, in the first row of actuators, segments 60m-1, 60m, and 60m+1 are positioned relative to the control electrode OE. m-1 OE m or OE m+1 Centered. This arrangement can be continued accordingly to the left, right, down, and up, such as... Figure 4 As indicated by the continuation point.

[0092] The weakly conductive segments 60 are separated from their respective directly adjacent segments, specifically, they are separated from each other by electrically insulating separators 93. Thus, separators 93 extend around segment 60n, making this segment electrically insulated from segments 60n-1, 60n+1, 60m, and any segments that may be connected above it. The corresponding current flow between these segments occurs only through the corresponding current measuring device 94. This current flow between two segments is the leakage current mentioned above between the relevant control electrodes 62. In the embodiment described herein, this leakage current can be accurately measured by means of the current measuring device 94.

[0093] For this purpose, the current measuring device 94 is connected to each section via current conductors 95 through contact points 61 respectively arranged at the edges of relevant sections of the weakly conductive structure 60. For example, it is used to measure leakage current. The current measuring device 94 is connected to the contact point 96 on section 60n-1 and section 60n via corresponding current conductors 95.

[0094] according to Figure 4 The electronic unit 40B and according to Figure 3 The difference in the electronic unit 40A is that it has a current measuring device 94 for measuring leakage current 97, and that the AC voltage source 82 and the current measuring device 84 are not connected according to... Figure 3 The measuring electrode 58 is not connected between the base electrode 56 and the measuring electrode 58, but rather between the control electrodes 62n-1, 62n, and 62n+1 and the base electrode 56. The impedance Z, measured by the measuring device 80, is... n-1 (U A Z n (U A ) and Z n+1 (U A The determination of ) is similar to that of a reference. Figure 4 The described method is based on an AC voltage U applied by an AC voltage source 82. W and the current intensity determined by current measuring devices 84n-1, 84n, and 84n+1. , as well as It was carried out.

[0095] according to Figure 4 The function and basis of the evaluation device 88B Figure 3 The difference between evaluation device 88A and evaluation device 88B is that evaluation device 88B, when determining the deflection characteristic curve 90 from the impedance 86 related to the operating voltage, considers the leakage current 97 measured by the current measuring device 94. The overall leakage current 97 is... Figure 4 Leakage current vector I L The leakage current 97 is considered in the evaluation device 88B as follows: from the impedance Zn-1 (U A Z n (U A ) and Z n+1 (U A The measurement results, such as those obtained by subtracting the influence of leakage current on the current flow measured by current measuring device 84, are then used to determine the influence of leakage current on the current intensity. , as well as The effects of (see attached figures labeled 85n-1, 85n, 85n+1) are considered. This corrected impedance is then used to determine the deflection characteristic curve 90.

[0096] Figure 8 An exemplary embodiment 38C according to another aspect of the invention is shown. Figure 2 The adaptive optics element 38 has three actuators 36n-1, 36n, and 36n+1. Here, embodiment 38C includes a layer structure 39C and an electronic unit 40C. The layer structure 39C is related to... Figure 4 The difference in the layer structure of implementation 39B lies only in that the weakly conductive structure 60, as according to Figure 3 The layer is constructed as in embodiment 39A, extending continuously along the control electrode 52.

[0097] Electronic unit 40C and according to Figure 4 Like electronic unit 40B, it is configured to perform impedance measurements of actuators 36n-1, 36n, and 36n+1 directly on control electrodes 62n-1, 62n, and 62n+1. Furthermore, electronic unit 40C is also designed to subtract the effect of leakage current between adjacent control electrodes 62 caused by the weakly conductive structure 60 from the measurement results of the relevant impedance measurements. Unlike electronic unit 40B, where the subtraction is based on a measurement of the actual flowing leakage current 97, electronic unit 40C subtracts the effect of leakage current based on a predetermined coupling resistance RK (reference numeral 100) between each control electrode 62 and each adjacent control electrode 62.

[0098] exist Figure 8In the illustrated embodiment, the current measuring device 98 and the resistance determining device 99 for determining the coupling resistance 100 are integrated into the electronic unit 40C. As previously mentioned, the determination of the coupling resistance 100 is performed in calibration mode 76 before the adaptive optics module 38C is activated, which is performed within the exposure operating range of the projection exposure device 10. The determination of the coupling resistance 100 is performed in qualification mode 78, in which an electronic unit independent of the electronic unit 40C can also be used. Therefore, in another embodiment not shown in the figures, the electronic unit 40C may be designed only to perform control mode 74 and calibration mode 76, and thus configured without the current measuring device 98 and the resistance determining device 99.

[0099] exist Figure 6 The equivalent circuit diagram of actuators 36n-1, 36n, and 36n+1 of the adaptive optics module 38C is shown to explain the method for determining the coupling resistance 100. Wherein, Z... n-1 Z n and Z n+1 This indicates the impedance of actuators 36n-1, 36n, and 36n+1. and This indicates a coupling resistance of 100 between control electrodes 62n-1 and 62n, and between control electrodes 62n and 62n+1. To determine the coupling resistance... and In identification mode 78, a DC voltage is applied to the control electrode 62n by means of a corresponding voltage generator 66. Simultaneously, set the voltage on control electrodes 62n-1 and 62n+1, as well as all other adjacent control electrodes (if present), to 0V. =0V, =0V). Then, the DC current is measured using the current measuring device 98. as well as These DC currents correspond to the current flowing through the coupling resistor. and Leakage current as well as .

[0100] The resistance determination device then proceeds as follows based on the leakage current. and Determine the coupling resistance and : as well as The coupling resistance of the other adjacent control electrodes 62 is calculated similarly.

[0101] The coupling resistance is thus determined to be 100 (in Figure 8 It is also represented as a vector RK The data is transmitted to the evaluation device 88C and stored there. According to... Figure 8 The function and basis of the evaluation device 88C Figure 4 The difference between the evaluation device 88B and the evaluation device 88C is that, when determining the deflection characteristic curve 90 from the impedance 86 related to the operating voltage, the evaluation device 88C considers a predetermined coupling resistance 100 instead of directly measuring the leakage current 97. The consideration of the coupling resistance 100 in the evaluation device 88C is as follows: from the impedance Z... n-1 (U A Z n (U A ) and Z n+1 (U A The effects of each leakage current generated by the coupling resistor on the current flow measured by the current measuring device 84 are subtracted from the measurement results. The corrected impedance is then used to determine the deflection characteristic curve 90.

[0102] In the evaluation device 88C, based on Figure 6 The equivalent circuit diagram shown determines the leakage current based on the coupling resistor 100. For example, this leads to the current intensity I of actuator 36n. Zn as follows:

[0103]

[0104] Here, I n It is the current intensity of the adjacent actuator, U n It is the voltage on the adjacent actuator, U i It is the voltage on actuator 36n.

[0105] Optionally, the evaluation device 88C can also be configured to take into account the line resistance of the power supply lines to the control electrodes 62n-1, 62n, or 62n+1 when determining the deflection characteristic curve 90 from the impedance 86 related to the operating voltage. , as well as (See figure 102). The consideration of line resistance 102 is made by deducting their respective contributions to impedance Z. n-1 (U A Z n (U A ) and Z n+1 (U A The influence of measurement results such as those of [other parameters] is considered. The corrected impedance is then used to determine the deflection characteristic curve.

[0106] Line resistance , as well as This should be understood as the resistance of the connection lines from the voltage generator 66 and the AC voltage source 82 to the control electrodes 62n-1, 62n, or 62n+1, including the contact resistance generated when the connection lines contact the control electrodes 62n-1, 62n, or 62n+1. Line resistance 102 in... Figure 7 The equivalent circuit diagram is shown.

[0107] To determine the line resistance 102, the frequency of the AC voltage source 82 is set so high that the corresponding ohmic equivalent resistances of actuators 36n-1, 36n, and 36n+1 approach zero, meaning that the ohmic equivalent resistances become negligible compared to the value of the relevant line resistance 102. This implies that the corresponding ohmic equivalent resistances are less than 10% of the relevant line resistance value, and particularly less than 5% of the relevant line resistance value. The frequency set for the AC voltage source 82 at this time can be, for example, at least 10 kHz, and particularly at least 100 kHz. According to one embodiment, this frequency is in the range of 100 kHz to 1 MHz.

[0108] After setting the aforementioned high frequency on the AC voltage source 82, the corresponding test voltages are sequentially set on the individual control electrodes 62n-1, 62n, and 62n+1 using the voltage generator 66. , or The corresponding, generated test current intensity is measured by means of a current measuring device 98. , or Resistance determining device 99 usage relationship Determine the line resistance , as well as .

[0109] The measurement function of line resistance 102 and its consideration in determining the deflection characteristic curve 90 can optionally be integrated into the system based on... Figure 4 In the adaptive optics module 38B. In this embodiment, besides Figure 4 In addition to the configuration shown, the optical module 38B also includes... Figure 8 The current measuring device 98 shown in the figure and the resistance determining device having the function of determining the line resistance 102 are also shown in the figure.

[0110] Figure 9A schematic diagram of a microlithography projection exposure apparatus 210 configured to operate in the DUV wavelength range is shown, comprising an illumination optics system in the form of a beamforming and illumination system 216 and a projection lens 222. Here, DUV stands for "deep ultraviolet," indicating that the wavelength of the exposure radiation 214 used in the projection exposure apparatus 210 is between 100 nm and 250 nm. The beamforming and illumination system 216 and the projection lens 222 may be arranged in a vacuum housing and / or surrounded by a machine chamber with corresponding drive mechanisms.

[0111] The DUV projection exposure apparatus 210 has a DUV exposure radiation source 212. For this purpose, an ArF excimer laser can be provided, for example, which emits exposure radiation 214 in the DUV range, for example, about 193 nm.

[0112] Figure 9 The beamforming and illumination system 216 shown directs exposure radiation 214 onto a photomask 218. The photomask 218 is configured as a transmission optical element and can be disposed outside systems 216 and 222. The photomask 218 has a structure that is imaged in reduced size onto a substrate 224, which is in the form of a wafer or similar, by means of a projection lens 222. The substrate 224 is movably supported on a substrate shifting stage 226.

[0113] The projection lens 222 has a plurality of optical elements 230 in the form of lenses and / or mirrors for imaging the photomask 218 onto the substrate 224. In the illustrated embodiment, the optical elements 230 include lenses 230-1, 230-4, and 230-5, a mirror 230-3, and another mirror 230-2 configured as an adaptive optics module 38. The individual lenses and / or mirrors of the projection lens 222 can be arranged symmetrically with respect to the optical axis 223 of the projection lens 222. It should be noted that the number of lenses and mirrors in the DUV projection exposure apparatus 210 is not limited to the number shown. More or fewer lenses and / or mirrors may also be provided. Furthermore, the mirrors are typically bent at their front side for beam shaping.

[0114] The air gap between the last lens 230-5 and the substrate 224 can be replaced by a liquid medium 231 with a refractive index >1. The liquid medium 231 can be, for example, high-purity water. This configuration is also known as immersion lithography and offers improved lithographic resolution. The medium 231 can also be referred to as an immersion liquid.

[0115] exist Figure 9 In the illustrated embodiment, the adaptive optics module 38 is similar to that according to Figure 1 It is constructed using an adaptive optics module 38, which of course includes... Figure 1Another different mirror element. The adaptive optics module 38 is designed such that the shape of the surface 232 of the mirror 230-2 can be actively changed to correct local shape errors. Therefore, the mirror surface is also referred to as the active optics mirror surface 232. Here, according to Figure 9 The adaptive optics module 38 can be in Figure 2 , 3 Configured as one of the embodiments shown in 4 and 8. Therefore, the preceding reference Figures 1 to 8 All statements regarding the adaptive optics module 38 can be transferred to... Figure 9 On the adaptive optics module 38.

[0116] Similar to according to Figure 1 The projection exposure device 10, according to Figure 9 The adaptive optics module 38 is controlled by control signals 42, which are determined by the control device 41 based on the wavefront deviation 46 of the projection lens 222 measured by means of the wavefront measurement device 44. Without limiting generality, Figure 9 Only one actuator device is shown, but it should be understood that multiple actuator devices are preferred, each of which can be individually controlled and / or adjusted.

[0117] The above description of exemplary embodiments, implementation methods, or variations should be understood as exemplary. This disclosure enables those skilled in the art to understand the invention and its related advantages, and also covers obvious changes and modifications to the described structures and methods that are within the understanding of those skilled in the art. Therefore, all such changes and modifications, as long as they fall within the scope of the invention as defined in the appended claims, and their equivalents, should be covered by the scope of the claims.

[0118] List of reference numerals

[0119] 10. Projection Exposure Equipment

[0120] 12. Exposure of radiation sources

[0121] 14. Exposure to radiation

[0122] 16 Illumination Optical System

[0123] 18 Masks

[0124] 20 Mask shifting stage

[0125] 22 Projection lens

[0126] 24 substrate

[0127] 26. Substrate shifting stage

[0128] 28 Exposure beam path

[0129] 30-1, 30-2, 30-3, 30-4, 30-5, 30-6, 30-7, 30-8 Reflecting Mirror Elements

[0130] 32 Active optical surfaces

[0131] 34 Supporting elements

[0132] 36, 36n-1, 36n, 36n+1 actuators

[0133] 38, 38A, 38B, 38C Adaptive Optics Modules

[0134] 39A layer structure

[0135] 39B layer structure

[0136] 39C layer structure

[0137] 40A Electronic Unit

[0138] 40B Electronic Unit

[0139] 40C Electronic Unit

[0140] 41 Control equipment

[0141] 42 Control Signals

[0142] 43 Deflection

[0143] 43s Target deflection

[0144] 44 Wavefront Measurement Device

[0145] 46 Wavefront deviation

[0146] 48 Dielectric

[0147] 52 Actuator Section

[0148] 54 Insulation layer

[0149] 56 Basic Electrode

[0150] 58, 58n-1, 58n, 58n+1 Measuring electrodes

[0151] 60 Weakly conductive structure

[0152] 62, 62n-1, 62n, 62n+1 control electrodes

[0153] 64 Multi-layer layout

[0154] 65 Smooth and insulating layer

[0155] 66 Voltage Generator

[0156] 68 Operating voltage

[0157] 69 Conversion Scheme

[0158] 70 Reference Characteristic Curve

[0159] 72 Control Unit

[0160] 74 Control Mode

[0161] 76 Calibration Modes

[0162] 78 Identification Mode

[0163] 80 Measuring device

[0164] 82 AC voltage source

[0165] 83. Measuring Voltage

[0166] 84, 84n-1, 84n, 84n+1 Current measuring devices

[0167] Current intensity of 85n-1, 85n, 85n+1

[0168] Impedances of 86n-1, 86n, and 86n+1 related to the operating voltage

[0169] 88A Evaluation Device

[0170] 88B Evaluation Device

[0171] 88C Evaluation Device

[0172] 90° deflection characteristic curve

[0173] Schematic diagram of 90d deflection characteristic curve

[0174] 91 Comparison Module

[0175] 92 Correction

[0176] 93 Electrically Insulated Separator

[0177] 94 Current measuring device

[0178] 95 Current Conductor

[0179] 96 contact points

[0180] 97 Leakage Current

[0181] 98 Current measuring device

[0182] 99 Resistance Determination Device

[0183] 100 coupling resistor

[0184] 102 Line Resistance

[0185] 210 Projection Exposure Equipment

[0186] 212 Exposure of Radiation Source

[0187] 214 Exposure Radiation

[0188] 216 Beam shaping and illumination systems

[0189] 218 Photomask

[0190] 222 Projection lens

[0191] 223 optical axis

[0192] 224 substrate

[0193] 226 Substrate Transfer Stage

[0194] 230 Optical Components

[0195] 230-1, 230-4, 230-5 lenses

[0196] 230-2 Adaptive Optics Module

[0197] 230-3 Reflector

[0198] 231 Liquid Medium

[0199] 232 Active optical mirror surface

Claims

1. An adaptive optics module (38A) for a microlithography projection exposure apparatus (10; 210) having an optical surface (32) for interacting with the exposure radiation (14) of the projection exposure apparatus and a plurality of actuators (36n-1, 36n, 36n+1) for changing the shape of the optical surface. in, The adaptive optics module has a dielectric (48) that can be deformed by applying a voltage (68), and each actuator includes a separate control electrode (62n-1, 62n, 62n+1), each control electrode being arranged to generate a corresponding electric field in a layer of the dielectric. The control electrodes are interconnected via a weakly conductive structure (60) with a conductivity of at least 0.1 mS / m, and In order to measure the impedance (86n-1, 86n, 86n+1) of at least one actuator, measuring electrodes (58n-1, 58n, 58n+1) are arranged between the control electrode of the actuator being measured and the dielectric.

2. The adaptive optics module according to claim 1, in, The weakly conductive structure (60) is configured as a layer disposed between the control electrodes (62n-1, 62n, 62n+1) of the actuator and the dielectric (48).

3. The adaptive optics module according to claim 1 or 2, in, The layer composed of the weakly conductive structure (60) extends continuously along the control electrodes (62n-1, 62n, 62n+1) of the actuator.

4. The adaptive optics module according to any one of the preceding claims, It also includes at least one base electrode (56) arranged as a counter electrode relative to the control electrodes (62n-1, 62n, 62n+1) and configured to generate a corresponding electric field in the dielectric (48) together with the respective control electrodes.

5. An adaptive optics module (38B; 38C) for a microlithography projection exposure apparatus (10; 210) having an optical surface for interacting with the exposure radiation (14) of the projection exposure apparatus and a plurality of actuators (36n-1, 36n, 36n+1) for changing the shape of the optical surface. in, The adaptive optics module has a dielectric (48) that can be deformed by applying a voltage (68), and each actuator includes a separate control electrode (62n-1, 62n, 62n+1), each control electrode being arranged to generate an electric field in a layer of the dielectric. The control electrodes are interconnected via a weakly conductive structure (60) with a conductivity of at least 0.1 mS / m, and The adaptive optics module further includes an evaluation device (88B, 88C) configured to subtract from the measurement results, when measuring the impedance (86n-1, 86n, 86n+1) of at least one actuator, the effect of the current flow (97) between the control electrode (62n) of the actuator being measured and at least one other control electrode (62n+1) caused by the weakly conductive structure.

6. The adaptive optics module according to claim 5, It also includes at least one current measuring device (94) for measuring the current flow (97) between the control electrode (62n) of the actuator being measured and at least one additional control electrode (62n+1), wherein, The evaluation device (88B) is configured to subtract the effect from the measurement results based on the measured current flow (97).

7. The adaptive optics module according to claim 6, in, The weakly conductive structure (60) has multiple segments (60n-1, 60n, 60n+1), wherein one of the segments is arranged at the control electrode (62n) of the actuator being measured and at the at least one other control electrode (62n+1), and the two segments are conductively connected through the current measuring device (94).

8. The adaptive optics module according to claim 6, in, The weakly conductive sections (60n-1, 60n, 60n+1) are electrically insulated from each other except through the connection of the current measuring device (94).

9. The adaptive optics module according to claim 7 or 8, in, One segment of the weakly conductive structure (60n-1, 60n, 60n+1) is respectively arranged at the control electrode (62n) of the actuator being measured and at the control electrodes (62n-1, 62n+1, 62m) of all actuators directly adjacent to the actuator being measured, and the segment of the actuator being measured is conductively connected to each segment arranged at the directly adjacent actuators through their respective current measuring devices (94).

10. The adaptive optics module according to claim 5, in, The evaluation device (88C) is also configured to subtract from the measurement results the effect of a coupling resistance (100) based on at least one predetermined coupling resistance between the control electrode (62n) of the actuator being measured and the at least one additional control electrode (62n+1).

11. The adaptive optics module according to claim 10, It includes at least one current measuring device (98) for measuring the current flow from the additional control electrode (62n+1) when a test voltage is applied to the control electrode (62n) of the actuator under test.

12. The adaptive optics element according to any one of claims 5 to 11, It includes at least one voltage source (66, 82) connected to at least one of the control electrodes (62n-1, 62n, 62n+1), wherein, The evaluation device (88b, 88C) is configured to subtract the line resistance (102) from the voltage source to the control electrode from the measurement result when measuring the impedance (86) of the at least one control electrode.

13. The adaptive optics element according to claim 12, It includes an AC voltage source (82) configured to apply an AC voltage (83) of such high frequency to the at least one control electrode in order to determine the line resistance (102) of the at least one control electrode, such that the ohmic equivalent resistance of the actuator associated with the control electrode drops to less than 10% of the value of the line resistance (102).

14. The adaptive optics module according to any one of claims 5 to 13, It also includes a measuring device (80) configured to measure the current intensity (85n-1, 85n, 85n+1) flowing from the respective control electrode when measuring the respective impedance of each actuator.

15. The adaptive optics element according to any one of the preceding claims, It also includes evaluation devices (88A, 88B, 88C) configured to calculate actuator deflection (90°) from the measured impedance (86n-1, 86n, 86n+1) of one of the actuators.

16. The adaptive optics element according to claim 15, It also includes a control unit (72) configured to correct the control variable (68) applied to the associated control electrode based on the calculated actuator deflection.

17. A projection exposure apparatus (10; 210) for microlithography, having at least one adaptive optics module (38A, 38B, 38C) according to any one of the preceding claims.

18. A method for determining the corresponding deflections of a plurality of actuators (36n-1, 36n, 36n+1) of an adaptive optics module (38A) of a microlithography projection exposure apparatus (10; 210), the actuators being configured to change the shape of an optical surface (32) of the optical module, wherein, The adaptive optics module includes a dielectric (48) capable of being deformed by voltage, each actuator having a separate control electrode (62n-1, 62n, 62n+1) for generating a corresponding electric field in a layer of the dielectric, the control electrodes being interconnected by a weakly conductive structure (60) with a conductivity of at least 0.1 mS / m, and the method comprising the following steps: - The impedance (86n-1, 86n, 86n+1) of at least one actuator in the actuators is measured using measuring electrodes (58n-1, 58n, 58n+1) arranged between the control electrode and the dielectric of the actuator being measured. - Calculate the corresponding deflection of each actuator (43n-1, 43n, 43n+1) from the corresponding measured impedance.

19. A method for determining the corresponding deflection of a plurality of actuators of an adaptive optics module (38B; 38C) of a microlithography projection exposure apparatus (10; 210), the actuators being configured to change the shape of an optical surface (32) of the optical module, wherein, The adaptive optics module includes a dielectric (48) capable of being deformed by voltage, each actuator having a separate control electrode (62n-1, 62n, 62n+1) for generating a corresponding electric field in a layer of the dielectric, the control electrodes being interconnected by a weakly conductive structure (60) with a conductivity of at least 0.1 mS / m, and the method comprising the following steps: - Measure the impedance (86n-1, 86n, 86n+1) of at least one of the actuators. - Subtract the effect of current flow caused by the weakly conductive structure (60) from the impedance measurement results, wherein the current flow occurs between the control electrode of the actuator being measured and at least one other control electrode, and - Calculate the corresponding deflection of each actuator (43n-1, 43n, 43n+1) from the corresponding measured impedance.

20. The method according to claim 19, in, The current flow caused by the weakly conductive structure (60) is measured by means of a current measuring device (94), and the effect is subtracted from the measurement result of the impedance measurement based on the measured current flow (97).

21. The method according to claim 19, in, The coupling resistance (100) between the control electrode (62n) of the actuator being measured and the at least one additional control electrode (62n+1) is determined, and the effect is subtracted from the measurement result of the impedance measurement based on the determined coupling resistance.

22. The method according to any one of claims 19 to 21, in, By applying an AC voltage (83) of such a high frequency to the control electrode, such that the ohmic equivalent resistance of the actuator associated with the control electrode drops to less than 10% of the value of the line resistance (102), the line resistance (102) of at least one electrical connection between at least one voltage source and at least one control electrode is determined.

23. The method according to any one of claims 19 to 22, in, During the exposure of the substrate by the projection exposure equipment (10; 210), the effect of current flow caused by the weakly conductive structure (60) is subtracted from the measurement results of the impedance measurement.

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