Drive device, optical system and lithography apparatus

Abstract

A drive device (100) for driving at least one actuator (200) for actuating an optical element (310) of an optical system (300), comprising an end stage (110) which is configured to boost an input voltage (V1) using a quiescent current (I1) of the end stage (110) to a drive voltage (V2) for the actuator (200), and a supply device (120) which is configured to adjust the quiescent current (I1) for the end stage (110) depending on at least one parameter (E1, E2, E3, E4) that is indicative of the power loss in the optical system (300).

Description

[0001] CONTROL DEVICE, OPTICAL SYSTEM AND LITHOGRAPHY SYSTEM

[0002] The present invention relates to a control device for controlling at least one actuator of an optical system, an optical system with such a control device and a lithography system with such an optical system.

[0003] The content of the priority application DE 10 2023 207 185.1 is incorporated in its entirety by reference.

[0004] Microlithography systems are known that feature actuatable optical elements, such as microlens arrays or micromirror arrays. Microlithography is used to manufacture microstructured components, such as integrated circuits. The microlithography process is carried out using a lithography system that features an illumination system and a projection system.

[0005] Driven by the pursuit of ever smaller structures in the production of integrated circuits, EUV lithography systems are currently being developed that use light with a wavelength in the range of 0.1 nm to 30 nm, particularly 13.5 nm. Since most materials absorb light at this wavelength, such EUV lithography systems must use reflective optics, i.e., mirrors, instead of the previously used refractive optics, i.e., lenses.

[0006] The image of a mask (reticle) illuminated by the illumination system is projected by the projection system onto a substrate coated with a light-sensitive layer (photoresist) and positioned in the image plane of the projection system, such as a silicon wafer, to transfer the mask structure to the light-sensitive coating of the substrate. Actuable optical elements can be used to improve the image of the mask on the substrate. For example, wavefront errors during exposure that lead to enlarged and / or blurred images can be compensated.

[0007] A MEMS actuator (MEMS; Microelectromechanical System) or a PMN actuator (PMN; Lead Magnesium Niobate), for example, can be used as an actuator. A PMN actuator enables distance positioning in the sub-micrometer or sub-nanometer range. When a direct current is applied, the actuator, whose actuator elements are stacked on top of one another, experiences a force that causes a specific linear expansion. The position set by the direct current (DC) voltage can be negatively influenced by external electromechanical crosstalk at the inherently resulting resonance points of the actuator controlled by the direct current. MEMS mirrors and actuators suitable for controlling them are described, for example, in DE 10 2016 213 025 A1.For precise actuator control, such as for a large number of MEMS mirrors, a Class A amplifier is advantageous as the output stage due to its low signal distortion. However, a disadvantage of Class A amplifiers is their high quiescent current, which can lead to significant heat dissipation.

[0008] For example, in MEMS systems, the micromirror arrays are not consistently illuminated. Depending on the lighting setting used, significant differences can arise when illuminating the various MEMS mirrors. The resulting temperature difference can lead to deformations on the mirror surface, since the MEMS mirror surface is coated with a reflective layer that has a different temperature coefficient. Repeated heating and cooling after changing lighting settings can lead to increased material stress and thus a higher probability of failure. Furthermore, such deformations can also affect the system performance of the lithography system.

[0009] Against this background, one object of the present invention is to improve the control of an actuator of an optical system.

[0010] According to a first aspect, a control device for controlling at least one actuator is proposed. The control device comprises: an output stage configured to amplify an input voltage into a control voltage for the actuator using a quiescent current of the output stage, and a supply device configured to adjust the quiescent current for the output stage as a function of at least one parameter indicative of a power loss of the optical system.

[0011] As explained above, the optical system comprises a large number of optical elements, e.g. mirrors, in particular MEMS mirrors, which are not continuously illuminated equally during operation. Because the present provision device sets the quiescent current as a function of the at least one parameter indicative of the power loss of the optical system, the provision device can influence and in particular adjust the temperature of the associated optical element by adjusting the quiescent current. This advantageously allows temperature differences between illuminated and unilluminated optical elements to be reduced or compensated for. Consequently, the provision device, or in the case of a plurality of control devices, a plurality of provision devices, creates a temperature setting, in particular a temperature control.This can provide increased temperature stability of the optical system, which reduces the probability of failure of components of the optical system.

[0012] In the present case, power loss of the optical system means in particular the thermal power loss of the optical system, in particular the heat dissipation. Parameters which are indicative of the thermal power loss of the optical system are, for example, the temperature, in particular the current temperature, of the optical element, the temperature, in particular the current temperature, of the actuator and the temperature, in particular the current temperature, of the control device. In particular, these components, i.e. the control device, the associated actuator and the associated optical element, are thermally coupled to one another. The fact that the control device is thermally coupled to the actuator and the optical element results in the following: If the quiescent current is increased, the thermal power loss in the control device increases and this heats up.Due to the thermal coupling, the actuator and the optical element are also heated. This allows the temperature of these components to be read back and influenced and controlled via the output stage. This control device can also be referred to as a control device with dynamic quiescent current.

[0013] The quiescent current is specifically the current that flows through the power amplifier, even when it is not dynamically active. The quiescent current is used to adjust the operating point at the output node. In this case, this operating point is temporarily shifted by the supply device as required. The quiescent current can also be referred to as bias current.

[0014] The actuator is, in particular, a MEMS actuator, a capacitive actuator, for example, a PMN actuator (PMN; lead magnesium niobate) or a PZT actuator (PZT; lead zirconate titanate) or a LiNbO3 actuator (lithium niobate). The actuator is, in particular, configured to actuate an optical element of the optical system. Examples of such an optical element include lenses, mirrors, and adaptive mirrors.

[0015] The optical system is preferably a projection optics system of the lithography system or projection exposure system. However, the optical system can also be an illumination system. The projection exposure system can be an EUV lithography system. EUV stands for "Extreme Ultraviolet" and refers to a wavelength of the working light between 0.1 nm and 30 nm. The projection exposure system can also be a DUV lithography system. DUV stands for "Deep Ultraviolet" and refers to a wavelength of the working light between 30 nm and 250 nm.

[0016] According to one embodiment, the supply device is configured to adjust, in particular to regulate, the quiescent current for the output stage as a function of the at least one parameter indicative of the power loss of the optical system and as a function of a specific dynamic requirement for the output stage and / or a desired position of the optical element.

[0017] The dynamic requirement specifies in particular the necessary dynamics of the output stage at a specific point in time. For example, if the capacitive actuator to be controlled needs to be recharged quickly, the dynamic requirement is high and the quiescent current increases quickly. The following example can illustrate this. For example, the dynamic requirement is based on a change in the input voltage of the output stage, preferably on a derivative of the input voltage dv / dt. In this example, a high dv / dt corresponds to a high dynamic requirement. Consequently, with a high dv / dt, the quiescent current is increased proportionally. In other words, dv / dt is directly proportional to the change in the quiescent current. With a negative dv / dt, the change and thus the effect is in the other direction. Here, the quiescent current is reduced, which advantageously reduces power consumption.

[0018] In other words, when high dynamic requirements are required, a high quiescent current is set to provide a correspondingly short actuator response time. Otherwise, a low quiescent current can be used to minimize the associated waste heat. Consequently, the temporarily increased quiescent current temporarily provides a high charge transfer rate.

[0019] According to a further embodiment, the at least one parameter indicative of the power loss of the optical system comprises: a determined temperature of the optical element, a determined temperature of the actuator, a determined temperature of the control device, and / or a parameter derived from the measured quiescent current of the output stage.

[0020] According to a further embodiment, the provision device is configured to adjust, in particular to regulate, the quiescent current for the output stage as a function of the determined temperature of the optical element, a target temperature of the optical element, the determined temperature of the actuator, a target temperature of the actuator, the determined temperature of the control device, a target temperature of the control device, a specific dynamic requirement for the output stage and a target position of the optical element.

[0021] According to a further embodiment, the control device comprises a first temperature sensor assigned to the optical element for providing the determined temperature of the optical element, a second temperature sensor assigned to the actuator for providing the determined temperature of the actuator, a third temperature sensor assigned to the control device for providing the determined temperature of the control device, and / or a determination unit which is configured to provide the parameter derived from the measured quiescent current of the output stage.

[0022] According to a further embodiment, the output stage comprises an input node for receiving the input voltage of the output stage, an output node for providing the drive voltage to the actuator, and a transistor coupled between the input node and the output node for amplifying the input voltage into the drive voltage.

[0023] According to a further embodiment, the supply device comprises a supply unit which is configured to adjust the quiescent current for the output stage as a function of the at least one parameter indicative of the power loss of the optical system for the output stage and to feed it into the output node of the output stage.

[0024] According to a further embodiment, the supply device comprises a control unit which is configured to supply a current as a function of the at least one parameter indicative of the power loss of the optical system, the determined dynamic requirement for the output stage and / or the desired position of the optical element, and a current mirror which is configured to mirror the current provided by the control unit to provide the quiescent current and to feed the provided quiescent current into the output node of the output stage.

[0025] The control unit is particularly in software, as a discrete circuit or as

[0026] Implemented by an ASIC. The current provided by the control unit is then mirrored into the quiescent current by the current mirror, which then feeds the provided quiescent current into the output node of the power stage.

[0027] According to a further embodiment, the control unit is configured to provide the current based on a change in the input voltage of the output stage, in particular based on a derivative of the input voltage of the output stage.

[0028] According to a further embodiment, the supply device comprises: a control unit which is configured to provide a voltage as a function of the at least one parameter indicative of the power loss of the optical system, the determined dynamic requirement for the output stage and / or the desired position of the optical element, a voltage-dependent current source which is configured to convert the voltage provided by the control unit into a current proportional thereto, and a current mirror which is configured to mirror the converted proportional current to provide the quiescent current and to feed the provided quiescent current into the output node of the output stage.

[0029] The control unit is implemented, in particular, in software, as a discrete circuit, or as an ASIC. The voltage provided by the control unit is then converted by the voltage-dependent current source into a correspondingly proportional current. This converted current is provided to the current mirror, which mirrors the converted proportional current and feeds it into the output stage as quiescent current. The current mirror can also be referred to as a current mirror circuit. According to a further embodiment, the control unit is configured to provide the voltage provided by the control unit based on a change in the input voltage of the output stage, in particular based on a derivative of the input voltage of the output stage.

[0030] According to another embodiment, the output stage comprises a Class A amplifier. The Class A amplifier has low signal distortion and thus enables precise actuator control.

[0031] According to a further embodiment, the output stage comprises a Class AB amplifier. The Class AB amplifier is a suitable alternative to the proposed Class A amplifier.

[0032] According to a further embodiment, the control device comprises a plurality N of output stages for respectively controlling an actuator using a respective control voltage. The current mirror is configured to mirror the current indicative of the specific dynamic requirement N-fold to provide a respective quiescent current and to feed the respectively provided quiescent current into the respective output node of the respective output stage.

[0033] This embodiment is particularly advantageous when a plurality N of optical elements are to be controlled by a corresponding plurality N of actuators. In this embodiment, only a single current mirror is required to control the N actuators, which current mirror N-fold mirrors the current indicative of the specific dynamic requirement, valid for all N actuators, in order to provide a respective quiescent current for the respective output stage. A further advantage, in addition to the use of a smaller number of components, namely only one current mirror, is that the N output stages can be controlled identically. The respective unit, for example the control unit, can be implemented in hardware and / or software. In a hardware implementation, the unit can be designed as a device or as part of a device, for example as a computer or as a microprocessor or as part of the control device.In a software implementation, the unit can be implemented as a computer program product, as a function, as a routine, as part of a program code or as an executable object.

[0034] According to a second aspect, an optical system having a plurality of actuatable optical elements is proposed, wherein each of the actuatable optical elements of the number is assigned an actuator, wherein each actuator is assigned a control device for controlling the actuator according to the first aspect or according to one of the embodiments of the first aspect.

[0035] The optical system comprises in particular a micromirror array and / or a microlens array with a plurality of independently actuatable optical elements.

[0036] In embodiments, groups of actuators can be defined, with all actuators in a group being assigned the same control device.

[0037] According to one embodiment, the optical system is designed as an illumination optics or as a projection optics of a lithography system.

[0038] According to a further embodiment, the optical system comprises a vacuum housing in which the actuatable optical elements, the associated actuators, and the control device are arranged. According to a third aspect, a lithography system is proposed which comprises an optical system according to the second aspect or according to one of the embodiments of the second aspect.

[0039] The lithography system is, for example, an EUV lithography system whose working light lies in a wavelength range from 0.1 nm to 30 nm, or a DUV lithography system whose working light lies in a wavelength range from 30 nm to 250 nm.

[0040] "One" in this case is not necessarily limited to a single element. Rather, multiple elements, such as two, three, or more, may also be included. Any other counting term used here should not be understood as implying a limitation to the exact number of elements mentioned. Rather, numerical deviations upwards and downwards are possible, unless otherwise stated.

[0041] Further possible implementations of the invention also include combinations of features or embodiments described above or below with respect to the exemplary embodiments that are not explicitly mentioned. In this case, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.

[0042] Further advantageous embodiments and aspects of the invention are the subject of the dependent claims and the exemplary embodiments of the invention described below. The invention is explained in more detail below using preferred embodiments with reference to the accompanying figures. Fig. 1 shows a schematic meridional section of a projection coating system for EUV projection lithography;

[0043] Fig. 2 shows a schematic representation of an embodiment of an optical system;

[0044] Fig. 3 shows a schematic block diagram of a first embodiment of a control device for controlling an actuator for actuating an optical element of an optical system;

[0045] Fig. 4 shows a schematic block diagram of a second embodiment of a control device for controlling an actuator for actuating an optical element of an optical system; and

[0046] Fig. 5 shows a schematic block diagram of a third embodiment of a control device for controlling an actuator for actuating an optical element of an optical system.

[0047] In the figures, identical or functionally equivalent elements are provided with the same reference numerals unless otherwise indicated. Furthermore, it should be noted that the representations in the figures are not necessarily to scale.

[0048] Fig. 1 shows an embodiment of a projection exposure system 1 (lithography system), in particular an EUV lithography system. One embodiment of an illumination system 2 of the projection exposure system 1 has, in addition to a light or radiation source 3, an illumination optics 4 for illuminating an object field 5 in an object plane 6. In an alternative embodiment, the light source 3 can also be provided as a separate module from the rest of the illumination system 2. In this case, the illumination system 2 does not include the light source 3.

[0049] A reticle 7 arranged in the object field 5 is exposed. The reticle 7 is held by a reticle holder 8. The reticle holder 8 can be displaced via a reticle displacement drive 9, in particular in a scanning direction.

[0050] For illustrative purposes, Fig. 1 shows a Cartesian coordinate system with an x-direction (x), a y-direction (y), and a z-direction (z). The x-direction (x) runs perpendicular to the drawing plane. The y-direction (y) runs horizontally, and the z-direction (z) runs vertically. The scanning direction in Fig. 1 runs along the y-direction (y). The z-direction (z) runs perpendicular to the object plane (6).

[0051] The projection exposure system 1 comprises a projection optics 10. The projection optics 10 serves to image the object field 5 into an image field 11 in an image plane 12. The image plane 12 runs parallel to the object plane 6. Alternatively, an angle other than 0° between the object plane 6 and the image plane 12 is also possible.

[0052] A structure on the reticle 7 is imaged onto a light-sensitive layer of a wafer 13 arranged in the image plane 12 in the region of the image field 11. The wafer 13 is held by a wafer holder 14. The wafer holder 14 can be displaced, in particular along the y-direction y, via a wafer displacement drive 15. The displacement of the reticle 7, on the one hand, via the reticle displacement drive 9, and the displacement of the wafer 13, on the other hand, via the wafer displacement drive 15, can be synchronized with each other.

[0053] The light source 3 is an EUV radiation source. The light source 3 emits, in particular, EUV radiation 16, which is also referred to below as useful radiation, illumination radiation, or illumination light. The useful radiation 16 has, in particular, a wavelength in the range between 5 nm and 30 nm. The light source 3 can be a plasma source, for example, an LPP source (Laser Produced Plasma, plasma generated with the aid of a laser) or a DPP source (Gas Discharged Produced Plasma, plasma generated by gas discharge). It can also be a synchrotron-based radiation source. The light source 3 can be a free-electron laser (FEL).

[0054] The illumination radiation 16 emanating from the light source 3 is focused by a collector 17. The collector 17 can be a collector with one or more ellipsoidal and / or hyperboloidal reflection surfaces. The at least one reflection surface of the collector 17 can be exposed to the illumination radiation 16 at grazing incidence (Gl), i.e., at angles of incidence greater than 45°, or at normal incidence (NI), i.e., at angles of incidence less than 45°. The collector 17 can be structured and / or coated, on the one hand, to optimize its reflectivity for the useful radiation and, on the other hand, to suppress stray light.

[0055] After the collector 17, the illumination radiation 16 propagates through an intermediate focus in an intermediate focal plane 18. The intermediate focal plane 18 can represent a separation between a radiation source module, comprising the light source 3 and the collector 17, and the illumination optics 4.

[0056] The illumination optics 4 comprises a deflecting mirror 19 and, downstream of this in the beam path, a first facet mirror 20. The deflecting mirror 19 can be a flat deflecting mirror or, alternatively, a mirror with a beam-influencing effect beyond the pure deflection effect. Alternatively or additionally, the deflecting mirror 19 can be designed as a spectral filter that separates a useful light wavelength of the illumination radiation 16 from stray light of a different wavelength. If the first facet mirror 20 is arranged in a plane of the illumination optics 4 that is optically conjugate to the object plane 6 as the field plane, it is also referred to as a field facet mirror. The first facet mirror 20 comprises a plurality of individual first facets 21, which can also be referred to as field facets. Only a few of these first facets 21 are shown in Fig. 1 as examples.

[0057] The first facets 21 can be designed as macroscopic facets, in particular as rectangular facets or as facets with an arcuate or partially circular edge contour. The first facets 21 can be designed as flat facets or, alternatively, as convexly or concavely curved facets.

[0058] As is known, for example, from DE 10 2008 009 600 A1, the first facets 21 themselves can also be composed of a plurality of individual mirrors, in particular a plurality of micromirrors. The first facet mirror 20 can, in particular, be designed as a microelectromechanical system (MEMS system). For details, reference is made to DE 10 2008 009 600 A1.

[0059] Between the collector 17 and the deflecting mirror 19, the illumination radiation 16 runs horizontally, i.e. along the y-direction y.

[0060] In the beam path of the illumination optics 4, a second facet mirror 22 is arranged downstream of the first facet mirror 20. If the second facet mirror 22 is arranged in a pupil plane of the illumination optics 4, it is also referred to as a pupil facet mirror. The second facet mirror 22 can also be arranged at a distance from a pupil plane of the illumination optics 4. In this case, the combination of the first facet mirror 20 and the second facet mirror 22 is also referred to as a specular reflector. Specular reflectors are known from US 2006 / 0132747 A1, EP 1 614 008 B1, and US Pat. No. 6,573,978.

[0061] The second facet mirror 22 comprises a plurality of second facets 23. In the case of a pupil facet mirror, the second facets 23 are also referred to as pupil facets.

[0062] The second facets 23 can also be macroscopic facets, which can, for example, be round, rectangular, or hexagonal, or alternatively facets composed of micromirrors. Reference is also made to DE 10 2008 009 600 A1 in this regard.

[0063] The second facets 23 can have planar or alternatively convex or concave curved reflection surfaces.

[0064] The illumination optics 4 thus form a double-faceted system. This basic principle is also known as a honeycomb condenser (EnglJ Fly's Eye Integrator).

[0065] It may be advantageous to arrange the second facet mirror 22 not exactly in a plane that is optically conjugate to a pupil plane of the projection optics 10. In particular, the second facet mirror 22 can be arranged tilted relative to a pupil plane of the projection optics 10, as described, for example, in DE 10 2017 220 586 A1.

[0066] With the help of the second facet mirror 22, the individual first facets

[0067] 21 into the object field 5. The second facet mirror 22 is the last bundle-forming or actually the last mirror for the illumination radiation 16 in the beam path in front of the object field 5.

[0068] In a further embodiment of the illumination optics 4 (not shown), a transmission optics can be arranged in the beam path between the second facet mirror 22 and the object field 5, which transmission optics contributes in particular to the imaging of the first facets 21 into the object field 5. The transmission optics can have exactly one mirror, but alternatively also two or more mirrors, which are arranged one behind the other in the beam path of the illumination optics 4. The transmission optics can in particular comprise one or two mirrors for normal incidence (Ni mirrors, normal incidence mirrors) and / or one or two mirrors for grazing incidence (Gl mirrors, grazing incidence mirrors).

[0069] In the embodiment shown in Fig. 1, the illumination optics 4 has exactly three mirrors after the collector 17, namely the deflection mirror 19, the first facet mirror 20 and the second facet mirror 22.

[0070] In a further embodiment of the illumination optics 4, the deflection mirror 19 can also be omitted, so that the illumination optics 4 can then have exactly two mirrors after the collector 17, namely the first facet mirror 20 and the second facet mirror 22.

[0071] The imaging of the first facets 21 by means of the second facets 23 or with the second facets 23 and a transmission optics into the object plane 6 is usually only an approximate imaging.

[0072] The projection optics 10 comprises a plurality of mirrors Mi, which are numbered according to their arrangement in the beam path of the projection exposure system 1. In the example shown in Fig. 1, the projection optics 10 comprises six mirrors M1 to M6. Alternatives with four, eight, ten, twelve or a different number of mirrors Mi are also possible. The projection optics 10 is a doubly obscured optic. The penultimate mirror M5 and the last mirror M6 each have a passage opening for the illumination radiation 16. The projection optics 10 has an image-side numerical aperture that is greater than 0.5 and can also be greater than 0.6 and can be, for example, 0.7 or 0.75.

[0073] Reflection surfaces of the mirrors Mi can be designed as freeform surfaces without a rotational symmetry axis. Alternatively, the reflection surfaces of the mirrors Mi can be designed as aspherical surfaces with exactly one rotational symmetry axis of the reflection surface shape. The mirrors Mi, like the mirrors of the illumination optics 4, can have highly reflective coatings for the illumination radiation 16. These coatings can be designed as multilayer coatings, in particular with alternating layers of molybdenum and silicon.

[0074] The projection optics 10 has a large object-image offset in the y-direction y between a y-coordinate of a center of the object field 5 and a y-coordinate of the center of the image field 11. This object-image offset in the y-direction y can be approximately as large as a z-distance between the object plane 6 and the image plane 12.

[0075] The projection optics 10 can, in particular, be anamorphic. They have, in particular, different image scales ßx, ßy in the x and y directions x, y. The two image scales ßx, ßy of the projection optics 10 are preferably (ßx, ßy) = (+ / - 0.25, / +- 0.125). A positive image scale ß means an image without image inversion. A negative sign for the image scale ß means an image with image inversion. The projection optics 10 thus leads to a reduction in the ratio 4'1 in the x direction x, i.e., in the direction perpendicular to the scanning direction.

[0076] The projection optics 10 leads to a reduction of 8D in the y-direction y, i.e. in the scanning direction.

[0077] Other magnifications are also possible. Magnifications with the same sign and absolutely identical in the x and y directions (x, y), for example, with absolute values ​​of 0.125 or 0.25, are also possible.

[0078] The number of intermediate image planes in the x- and y-directions x, y in the beam path between the object field 5 and the image field 11 can be the same or can be different, depending on the design of the projection optics 10. Examples of projection optics with different numbers of such intermediate images in the x- and y-directions x, y are known from US 2018 / 0074303 A1.

[0079] Each of the second facets 23 is assigned to exactly one of the first facets 21 to form a respective illumination channel for illuminating the object field 5. This can, in particular, result in illumination according to the Köhler principle. The far field is divided into a plurality of object fields 5 using the first facets 21. The first facets 21 generate a plurality of images of the intermediate focus on the second facets 23 assigned to them.

[0080] The first facets 21 are each imaged onto the reticle 7 by an associated second facet 23, superimposed on one another, to illuminate the object field 5. The illumination of the object field 5 is, in particular, as homogeneous as possible. It preferably has a uniformity error of less than 2%. Field uniformity can be achieved by superimposing different illumination channels.

[0081] By arranging the second facets 23, the illumination of the entrance pupil of the projection optics 10 can be geometrically defined. By selecting the illumination channels, in particular the subset of the second facets 23 that guide light, the intensity distribution in the entrance pupil of the projection optics 10 can be adjusted. This intensity distribution is also referred to as the illumination setting or illumination pupil fill.

[0082] A likewise preferred pupil uniformity in the area of ​​defined illuminated sections of an illumination pupil of the illumination optics 4 can be achieved by redistributing the illumination channels.

[0083] Further aspects and details of the illumination of the object field 5 and in particular of the entrance pupil of the projection optics 10 are described below.

[0084] The projection optics 10 can, in particular, have a homocentric entrance pupil. This can be accessible. It can also be inaccessible.

[0085] The entrance pupil of the projection optics 10 cannot usually be precisely illuminated with the second facet mirror 22. When imaging the projection optics 10, which telecentrically images the center of the second facet mirror 22 onto the wafer 13, the aperture rays often do not intersect at a single point. However, a surface can be found in which the pairwise determined distance of the aperture rays is minimized. This surface represents the entrance pupil or a surface conjugated to it in spatial space. In particular, this surface exhibits a finite curvature. It is possible for the projection optics 10 to have different positions of the entrance pupil for the tangential and for the sagittal beam path. In this case, an imaging element, in particular an optical component of the transmission optics, should be provided between the second facet mirror 22 and the reticle 7.With the help of this optical element, the different positions of the tangential entrance pupil and the sagittal entrance pupil can be taken into account.

[0086] In the arrangement of the components of the illumination optics 4 shown in Fig. 1, the second facet mirror 22 is arranged in a surface conjugate to the entrance pupil of the projection optics 10. The first facet mirror 20 is arranged tilted relative to the object plane 6. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the deflection mirror 19. The first facet mirror 20 is arranged tilted relative to an arrangement plane defined by the second facet mirror 22.

[0087] Fig. 2 shows a schematic representation of an embodiment of an optical system 300 for a lithography system or projection exposure system 1, as shown, for example, in Fig. 1. Furthermore, the optical system 300 of Fig. 2 can also be used, for example, in a DUV lithography system.

[0088] The optical system 300 of Fig. 2 has a plurality of actuatable optical elements 310. The optical system 300 is embodied here as a micromirror array, wherein the optical elements 310 are micromirrors. Each micromirror 310 is actuatable by means of an associated actuator 200. For example, a respective micromirror 310 can be tilted about two axes and / or displaced in one, two, or three spatial axes by means of the associated actuator 200. For reasons of clarity, the reference numerals are only shown for the top row of these elements. The control device 100 controls the respective actuator 200, for example, with a control voltage V2 (see Figs. 3 to 5). This sets a position of the respective micromirror 310. The control device 100 is described in particular with reference to Figs. 3 to 5.

[0089] Figure 3 shows a schematic block diagram of a first embodiment of a control device 100 for controlling an actuator 200 for actuating an optical element 310 of an optical system 300. In the embodiments of Figures 3 to 5, the actuator 200 is a capacitive actuator and is depicted as a capacitor in these Figures 3 to 5.

[0090] The control device 100 according to Fig. 3 comprises an output stage 110 and a supply device 120.

[0091] The output stage 110 is configured to amplify an input voltage VI using a quiescent current II of the output stage 110 into a drive voltage V2 for the actuator 200. The output stage 110 is preferably designed as a class-A amplifier and includes a transistor TI. The transistor TI is, for example, a field-effect transistor (FET). Alternatively, the transistor TI can also be designed as a bipolar transistor. As an alternative to the class-A amplifier, the output stage 110 can also be designed as a class-AB amplifier.

[0092] The output stage 110 comprises an input node K1 for receiving the input voltage VI, an output node K2 for providing the drive voltage V2 to the actuator 200, and the transistor T1 coupled between the input node K1 and the output node K2 for amplifying the input voltage VI into the drive voltage V2. The supply device 120 of Fig. 3 is configured to adjust the quiescent current II for the output stage 110 as a function of at least one parameter E1, E2, E3, P1 indicative of a power loss of the optical system 300. Examples of the at least one parameter E1, E2, E3, PI indicative of the power loss of the optical system 300 include a determined temperature E1 of the optical element 310, a determined temperature E2 of the actuator 200, a determined temperature E3 of the control device 100 and / or a parameter PI derived from the measured quiescent current II of the output stage 110.

[0093] To determine the temperature E1, in particular the current temperature E1, of the optical element 310, a temperature sensor 131 assigned to the optical element 310 can be used (see Figs. 4 and 5). Alternatively, the temperature E1 of the optical element 310 can be derived from another temperature measured in the optical system 300. Accordingly, the temperature E2 of the actuator 200 can be determined via a temperature sensor 132 assigned to the actuator 200 (see Figs. 4 and 5). Alternatively, the temperature E2 of the actuator 200, that is to say in particular the current temperature E2 of the actuator 200, can also be derived from another temperature measured in the optical system 300. The temperature E3 of the control device 100 can be measured via a temperature sensor 133 assigned to the control device 100 (see Figs. 4 and 5).Alternatively, the temperature E3, in particular the current temperature E3, of the control device 100 can be derived from another temperature measured in the optical system 300. To provide the parameter PI, for example, the quiescent current II flowing into the output node K2 is measured, and a temperature or the resulting waste heat is determined. The resulting waste heat can correspond in particular to the derived parameter PI. As illustrated in Fig. 3, the provision device 120 has a provision unit 121. The provision unit 121 of Fig.3 receives the determined temperature E1 of the optical element 310, the determined temperature E2 of the actuator 200, the determined temperature E3 of the control device 100, the parameter PI derived from the measured quiescent current II of the output stage 110, a desired position SP of the optical element 310 and a specific dynamic requirement DA for the output stage 110.

[0094] The supply unit 121 is configured to adjust, in particular to regulate, the quiescent current II for the output stage 110 as a function of the determined temperature E1 of the optical element 310, the determined temperature E2 of the actuator 200, the determined temperature E3 of the control device 100, the parameter PI derived from the measured quiescent current E1 of the output stage 110, the determined dynamic requirement DA for the output stage 110, and / or the target position SP of the optical element 310. Furthermore, the supply unit 121 is also configured to provide the input voltage VI for the output stage 110 based on the received parameters, namely E1, E2, E3, PI, SP, and / or DA.

[0095] The dynamic requirement DA can be specified or can be specified, for example, by a control device (not shown) of the optical system 300.

[0096] Fig. 4 shows a schematic block diagram of a second embodiment of a control device 100 for controlling an actuator 200 for actuating an optical element 310 of an optical system 300.

[0097] The second embodiment according to Fig. 4 differs from the first embodiment according to Fig. 3 in the design of the provision device 120. The provision device 120 according to Fig. 4 comprises a control unit 122 and a current mirror 123. The current mirror 123 can also be referred to as a current mirror circuit.

[0098] Furthermore, Fig. 4 shows the first temperature sensor 131 assigned to the optical element 310 for providing the determined temperature E1 of the optical element 310, the second temperature sensor 132 assigned to the actuator 200 for providing the determined temperature E2 of the actuator 200, the third temperature sensor 133 assigned to the control device 100 for providing the determined temperature E3 of the control device 100, and a determination unit 134 configured to provide the parameter PI derived from the measured quiescent current II of the output stage 110. The first temperature sensor 131, the second temperature sensor 132, the third temperature sensor 133, and the determination unit 134 are coupled to the control unit 122 and provide the parameters E1, E2, E3, and PI to it.Furthermore, the control unit 122 receives a target temperature S1 of the optical element 310, a target temperature S2 of the actuator 200, a target temperature S3 of the control device 100, the target position SP of the optical element 310, and the determined dynamic requirement DA for the output stage 110. The received target temperatures Si, S2, S3 are used for comparison with the respective currently determined temperatures E1, E2, E3. In the embodiment according to Fig. 4, the determined temperature E1, the determined temperature E2, the determined temperature E3, and the derived parameter PI form the parameters E1, E2, E3, PI indicative of the thermal power loss of the optical system 300.

[0099] Here, the control unit 122 is configured to provide a current I2 for the output stage 110 as a function of the parameters E1, E2, E3, P1 indicative of the thermal power loss of the optical system 300, the target temperatures S1, S2, S3 as a reference, the target position SP of the optical element 310, and / or the determined dynamic requirement DA. Similarly, the control unit 122 is configured to also provide the input voltage VI for the output stage 110 at the input node K1 of the output stage 110.

[0100] The current mirror 123 is supplied with a positive supply voltage V4 and is configured by means of its transistors T1 and T2 to mirror the current I2 provided by the control unit 122 to provide the quiescent current II and to feed the provided quiescent current II into the output node K2 of the output stage 110.

[0101] Figure 5 shows a schematic block diagram of a third embodiment of a control device 100 for controlling an actuator 200 for actuating an optical element 310 of an optical system 300. The third embodiment according to Figure 5 differs from the embodiments according to Figures 3 and 4 in the design of the provision device 120.

[0102] The supply device 120 according to Fig. 5 comprises a control unit 124, a voltage-dependent current source 125 and a current mirror 123.

[0103] The control unit 124 is configured to provide a voltage V3 as a function of the parameters E1, E2, E3, PI indicative of the power loss of the optical system 300, the target temperatures Si, S2, S3, the target position SP, the determined dynamic requirement DA and / or the derived parameter PI.

[0104] The voltage-dependent current source 125 is configured to convert the voltage V3 provided by the control unit 124 into a current I2 proportional thereto. Furthermore, the control unit 124 is also configured to provide the input voltage VI for the output stage 110 at the input node K1 of the output stage 110 depending on the received parameters E1-E3, S1-S3, SP, DA, and / or PI.

[0105] The voltage-dependent current source 125 comprises an operational amplifier O1, which is supplied by a supply voltage V5, a transistor T4, for example a field-effect transistor, and a resistor RI. The resistor RI is coupled to the inverting input of the operational amplifier O1 and to the transistor T4, as shown in Fig. 5. The transistor T4 provides the converted proportional current I2 to the current mirror 123 on the output side. The current mirror 123 is designed as explained for Fig. 4. Consequently, the current mirror 123 is configured to mirror the converted proportional current I2 to provide the quiescent current II and to feed the provided quiescent current II into the output node K2 of the output stage 110.

[0106] Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

[0107] LIST OF REFERENCE SYMBOLS

[0108] 1 projection exposure system

[0109] 2 lighting system

[0110] 3 Light source

[0111] 4 Lighting optics

[0112] 5 Object field

[0113] 6 Object level

[0114] 7 reticles

[0115] 8 reticle age

[0116] 9 Reticle displacement drive

[0117] 10 Projection optics

[0118] 11 Image field

[0119] 12 Image plane

[0120] 13 wafers

[0121] 14 wafer holders

[0122] 15 Wafer relocation drive

[0123] 16 Illumination radiation

[0124] 17 Collector

[0125] 18 Intermediate focal plane

[0126] 19 Deflecting mirrors

[0127] 20 first facet mirror

[0128] 21 first facet

[0129] 22 second facet mirror

[0130] 23 second facet

[0131] 100 control device

[0132] 110 power amplifier

[0133] 120 Provisioning device

[0134] 121 Provisioning Unit

[0135] 122 Control unit 123 Current mirror

[0136] 124 Control unit

[0137] 125 voltage-dependent current source

[0138] 131 Temperature sensor

[0139] 132 Temperature sensor

[0140] 133 Temperature sensor

[0141] 134 Investigation Unit

[0142] 200 actuator

[0143] 300 optical system

[0144] 310 optical element

[0145] DA dynamic requirement

[0146] E 1 determined temperature of the optical element

[0147] E2 determined temperature of the actuator

[0148] E3 determined temperature of the control device

[0149] 11 Quiescent current

[0150] 12 indicative current

[0151] Kl input node of the power amplifier

[0152] K2 Output node of the power amplifier

[0153] ml mirror

[0154] M2 mirror

[0155] M3 mirror

[0156] M4 mirror

[0157] M5 mirror

[0158] M6 mirror

[0159] 01 Operational amplifier

[0160] RI resistance

[0161] 51 Target temperature of the optical element

[0162] 52 Target temperature of the actuator

[0163] 53 Target temperature of the control device SP Target position of the optical element

[0164] TI Transistor

[0165] T2 transistor

[0166] T3 Transistor T4 Transistor

[0167] VI Input voltage

[0168] V2 control voltage

[0169] V3 indicative voltage

[0170] V4 Supply voltage V5 Supply voltage

Claims

PATENT CLAIMS 1. A control device (100) for controlling at least one actuator (200) for actuating an optical element (310) of an optical system (300), comprising an output stage (110) configured to amplify an input voltage (V1) using a quiescent current (V1) of the output stage (110) into a control voltage (V2) for the actuator (200), and a supply device (120) configured to adjust the quiescent current (V1) for the output stage (110) as a function of at least one parameter (E1, E2, E3, P1) indicative of a power loss of the optical system (300), wherein the supply device (120) is configured to adjust the quiescent current (V1) for the output stage (110) as a function of the determined temperature (E1) of the optical element (310), a target temperature (S1) of the optical element (310), the determined temperature (E2) of the actuator (200), a target temperature (S2) of the actuator (200),the determined temperature (E3) of the control device (100), a target temperature (S3) of the control device (100), a specific dynamic requirement (DA) for the output stage (110) and a target position (SP) of the optical element (310), in particular to regulate.

2. Control device according to claim 1, wherein the provision device (120) is configured to set, in particular to regulate, the quiescent current (11) for the output stage (110) as a function of the at least one parameter (E1, E2, E3, P1) indicative of the power loss of the optical system (300) and as a function of a specific dynamic requirement (DA) for the output stage (110) and / or a desired position (SP) of the optical element (310).

3. Control device according to claim 2, wherein the at least one parameter (El, E2, E3, Pl) indicative of the power loss of the optical system (300) comprises: a determined temperature (El) of the optical element (310), a determined temperature (E2) of the actuator (200), a determined temperature (E3) of the control device (100), and / or a parameter (Pl) derived from the measured quiescent current (Il) of the output stage (110).

4. Control device according to claim 1 or 3, further comprising: a first temperature sensor (131) assigned to the optical element (310) for providing the determined temperature (El) of the optical element (310), a second temperature sensor (132) assigned to the actuator (200) for providing the determined temperature (E2) of the actuator (200), a third temperature sensor (133) assigned to the control device (100) for providing the determined temperature (E3) of the control device (100), and / or a determination unit (134) which is configured to provide the parameter (Pl) derived from the measured quiescent current (Il) of the output stage (110).

5. Control device according to one of claims 1 to 4, wherein the output stage (110) has an input node (Kl) for receiving the input voltage (Vl) of the output stage (110), an output node (K2) for providing the control voltage (V2) to the actuator (200) and a transistor (Tl) coupled between the input node (Kl) and the output node (K2) for amplifying the input voltage (Vl) into the control voltage (V2).

6. Control device according to claim 5, wherein the supply device (120) has a supply unit (121) which is configured to set the quiescent current (11) for the output stage (110) as a function of the at least one parameter (TI, T2, T3, I1) indicative of the power loss of the optical system (300) for the output stage (110) and to feed it into the output node (K2) of the output stage (110).

7. Control device according to claim 5, wherein the provision device (120) comprises: a control unit (122) which is configured to provide a current (12) as a function of the at least one parameter (E1, E2, E3, P1) indicative of the power loss of the optical system (300) and the determined dynamic requirement (DA) for the output stage (110) and / or the desired position (SP) of the optical element (310), and a current mirror (123) which is configured to mirror the current (12) provided by the control unit (122) to provide the quiescent current (11) and to feed the provided quiescent current (11) into the output node (K2) of the output stage (110).

8. Control device according to claim 7, wherein the control unit (122) is configured to provide the current (12) based on a change in the input voltage (Vl) of the output stage (110), in particular based on a derivative of the input voltage (Vl) of the output stage (110).

9. Control device according to claim 5, wherein the provision device (120) comprises: a control unit (124) which is configured to generate a voltage (V3) as a function of the at least one parameter (E1, E2, E3, P1) indicative of the power loss of the optical system (300) and the specific dynamic requirement (DA) for the power amplifier (110) and / or the target Position (SP) of the optical element (310), a voltage-dependent current source (125) which is configured to convert the voltage (V3) provided by the control unit (124) into a current (I2) proportional thereto, and a current mirror (123) which is configured to mirror the converted proportional current (I2) to provide the quiescent current (I1) and to feed the provided quiescent current (I1) into the output node (K2) of the output stage (110).

10. Control device according to claim 9, wherein the control unit (124) is configured to provide the voltage (V3) provided by the control unit (124) based on a change in the input voltage (Vl) of the output stage (110), in particular based on a derivative of the input voltage (Vl) of the output stage (110).

11. Control device according to one of claims 7 to 10, wherein the control device (100) comprises a plurality N of output stages (110) for respectively controlling an actuator (200) by means of a respective control voltage (V2), wherein the current mirror (123) is configured to mirror the current (12) N-fold to provide a respective quiescent current (11) and to feed the respectively provided quiescent current (11) into the respective output node (K2) of the respective output stage (110).

12. Optical system (300) with a plurality of actuatable optical elements (310), wherein each of the actuatable optical elements (310) of the number is assigned an actuator (200), wherein each actuator (200) is assigned a control device (100) for controlling the actuator (200) according to one of claims 1 to 11.

13. The optical system according to claim 12, wherein the optical system (300) is designed as an illumination optics (4) or as a projection optics (10) of a lithography system (1).

14. The lithography system (1) with an optical system (300) according to claim 12 or 13.

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