Driving device, optical system and lithography device

Abstract

A driving device (100) for driving and measuring an actuator (200) for driving an optical element (310) of an optical system (300), and A driving unit (110) having a frequency-dependent first transfer function (G1), wherein the transfer function is configured to amplify a time-dependent AC voltage signal (W) using at least a first frequency range (F1) and a second frequency range (F2) to form a driving voltage (AS) for an actuator (200), and accordingly, the first frequency range (F1) experiences a higher gain compared to the second frequency range (F2) by a specific factor, the driving unit A voltage measuring unit (120) for providing a measured voltage (U), configured to convolve a time-dependent voltage (u) of an actuator (200) in the time domain with a second transfer function (G2) based on the reciprocal of a first transfer function (G1), and then measure the time-dependent voltage to provide a measured voltage (U), and The apparatus includes a current measuring unit (130) for providing a measured current (I), wherein the current measuring unit is configured to convolve a time-dependent current (i) of an actuator (200) in the time domain with a third transfer function (G3) based on the reciprocal of a first transfer function (G1), and then measure the time-dependent current to provide a measured current (I).

Description

Technology Field

[0001] The present invention relates to a driving device for driving and measuring an actuator of an optical system, an optical system including the driving device, and a lithography device including the optical system.

[0002] The contents of priority application DE 10 2022 203 255.1 are incorporated by reference in their entirety. Background Technology

[0003] For example, microlithography devices equipped with drivable optical elements, such as microlens element arrays or micromirror arrays, are known. Microlithography is used to manufacture microstructural components, such as integrated circuits. The microlithography process is performed using a lithography device equipped with an illumination system and a projection system.

[0004] Driven by the demand for increasingly smaller structures in the production of integrated circuits, EUV lithography devices using light with a wavelength in the range of 0.1 nm to 30 nm, particularly 13.5 nm, are currently under development. Since most materials absorb light of this wavelength, these EUV lithography devices must use reflective optical systems, i.e., mirrors, instead of refractive optical systems, i.e., lenses, as before.

[0005] An image of a mask (reticle) illuminated by a lighting system is projected onto a substrate, for example, a silicon wafer, by a projection system, wherein the substrate is coated with a photosensitive layer (photoresist) and aligned with the image plane of the projection system to transfer the mask structure to the photosensitive coating of the substrate. The mask imaging on the substrate can be enhanced through a driveable optical element. For example, wavefront aberrations during exposure that result in enlarged and / or blurred imaging can be compensated for.

[0006] Such correction through optical elements requires wavefront detection and signal processing to determine the position of each optical element that allows the wavefront to be corrected as desired. In the final step, the driving signal for each optical element is amplified and output to the actuator of the optical element.

[0007] For example, PMN actuators (PMN; lead magnesium niobate) can be used as actuators. PMN actuators enable position setting at distances in the sub-micrometer or sub-nanometer range. In this case, the actuator, in which actuator elements are stacked in layers, experiences a force that causes a specific linear expansion as a DC voltage is applied. The position set by the DC voltage (DC; Direct Current) can be negatively affected by external electromechanical crosstalk at the fundamentally occurring resonance point of the DC-driven actuator. Due to this electromechanical crosstalk, accurate position setting can no longer be achieved in a stable manner. In this case, mechanical resonance increases as the applied DC voltage increases. The resonance point can also change over the long term, for example, as a result of temperature drift, as a result of adhesive drift if the mechanical connection of the adhesive material changes, or as a result of hysteresis or aging. For example, impedance measurements would be helpful in this regard.

[0008] However, conventional impedance measuring devices are often too expensive and, moreover, lack inline capability, so they generally cannot be used in lithography devices. Furthermore, integrated impedance measuring bridges, which are generally designed for excessively high impedance values, have proven unsuitable for the present application in lithography devices because the range of impedance values ​​of interest here covers a size of several times and the range of interest is only a part of the total range.

[0009] In addition, it is a known practice to drive the actuator of a lithography device using respective drive signals having a low-frequency drive component for driving the actuator and a high-frequency measurement signal component for measuring the actuator. Typically, these drive signals are amplified through an output stage with a uniform gain across the frequency and applied to the actuator as a drive voltage. Such conventional output stages induce a uniform gain across the entire frequency range, and thus result in uniform resolution. If a high gain is selected for the gain through the output stage, this high gain degrades the resolution for measuring the impedance of the actuator. However, if a low gain is selected, the low gain is insufficient for applications involving driving the actuator. The problem to be solved

[0010] Against this backdrop, the objective of the present invention is to improve the driving of an actuator of an optical system. means of solving the problem

[0011] According to a first embodiment, a driving device for driving and measuring an actuator of an optical system is proposed. The driving device is:

[0012] A driving unit having a frequency-dependent first transfer function, wherein the transfer function is configured to amplify a time-dependent AC voltage signal using at least a first frequency range and a second frequency range to form a driving voltage for an actuator, and accordingly, the first frequency range experiences a higher gain compared to the second frequency range by a specific factor, the driving unit

[0013] A voltage measuring unit for providing a measurement voltage, configured to convolve a time-dependent voltage of an actuator with a second transfer function based on the reciprocal of a first transfer function in the time domain, and then measure the time-dependent voltage to provide a measurement voltage, and

[0014] The current measuring unit for providing a measuring current is configured to convolve the time-dependent current of an actuator with a third transfer function based on the reciprocal of a first transfer function in the time domain, and then measure the time-dependent current to provide a measuring current.

[0015] The driving device of the present invention advantageously enables high gain in a first frequency range for driving an actuator, and at the same time enables high resolution in a second frequency range for measuring the actuator, particularly for measuring the impedance of the actuator.

[0016] In this case, the driving voltage component of the first frequency range serves to drive the actuator, that is, specifically to control the deflection of the actuator. In this process, the first frequency range experiences higher gain compared to the second frequency range to properly drive the actuator. Prior to each measurement, that is, prior to voltage and current measurements, the first frequency range is attenuated and the second frequency range is amplified, thereby providing high resolution for measuring the actuator in the second frequency range.

[0017] The driving device of the present invention may also be referred to as a frequency-dependent amplifier stage for driving an actuator using integrated current and voltage measurements.

[0018] As a result of providing the measured voltage and measured current of the actuator, the driving device of the present invention enables the impedance behavior of the actuator, in particular the determination of the impedance of an actuator installed in a lithography device, to be determined in a fast and inline-capable manner.

[0019] Based on the determined impedance behavior of the actuator, appropriate solutions or countermeasures, particularly active inline correction or inline damping, can also be implemented through the driving signal.

[0020] In particular, the actuator is 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 configured to drive optical elements of an optical system in particular. Examples of such optical elements include lens elements, mirrors, and adaptive mirrors.

[0021] The optical system is preferably a projection optical unit of a lithography device or a projection exposure device. However, the optical system may also be an illumination system. The projection exposure device may be an EUV lithography device. EUV stands for "extreme ultraviolet" and represents an operating light wavelength of 0.1 nm to 30 nm. The projection exposure device may also be a DUV lithography device. DUV stands for "deep ultraviolet" and represents an operating light wavelength of 30 nm to 250 nm.

[0022] According to an embodiment, the driving device further comprises a determination unit coupled to a voltage measuring unit and a current measuring unit. The determination unit is configured to determine the impedance of the actuator based on a provided measured voltage and a provided measured current. In particular, this embodiment of the driving device may also be referred to as a frequency-dependent amplifier stage for driving and measuring the impedance of the actuator.

[0023] According to another embodiment, the first frequency range is located at 0 Hz to 1 kHz, preferably 0 Hz to 500 Hz, more preferably 0 Hz to 300 Hz.

[0024] According to another embodiment, the second frequency range is located at 5 kHz to 100 kHz, preferably 10 kHz to 100 kHz, more preferably 10 kHz to 60 kHz.

[0025] According to another embodiment, the specific factor is 100 to 2000, preferably 500 to 1500, more preferably 800 to 1200.

[0026] According to another embodiment, the driving unit includes an amplifier circuit, in particular a differential amplifier.

[0027] According to another embodiment, the amplifier circuit of the driving unit includes an input node for supplying an AC voltage signal, an output node for providing a driving voltage for an actuator, and an operational amplifier coupled between the input node and the output node. Here, to provide a first transfer function, a first circuit is coupled to the input node, the negative supply voltage of the driving device, and the non-inverting input of the operational amplifier, and a second circuit is coupled to the inverting input of the operational amplifier, ground, and the output node.

[0028] According to another embodiment, the first circuit and the second circuit each include a resistor circuit for adjusting gain in a first frequency range and for adjusting gain in a second frequency range, and each circuit further includes a frequency-dependent connectable circuit including a frequency-dependent component and a resistor. The frequency-dependent connectable circuit including the frequency-dependent component and the resistor is, for example, in the form of a capacitor and a resistor connected in series.

[0029] In this case, the capacitance of the capacitor is selected such that, in particular, the capacitor is conductive only at frequencies in the second frequency range, and thus the connectable circuit is connected frequency-dependently at frequencies in the second frequency range. Each frequency range may also be referred to as a frequency band.

[0030] According to another embodiment, the voltage measuring unit includes an amplifier circuit, in particular a differential amplifier.

[0031] According to another embodiment, the amplifier circuit of the voltage measurement unit includes an input node coupled to the output node of the amplifier circuit of the driving unit and serving to receive the time-dependent voltage of the actuator, an output node for providing a measurement voltage, and an operational amplifier coupled between the input node and the output node. Here, to provide a second transfer function, the first circuit is coupled to the output node, the negative supply voltage of the driving device and the inverting input of the operational amplifier, and the second circuit is coupled to the input node, the non-inverting input of the operational amplifier and ground.

[0032] According to another embodiment, the first circuit and the second circuit each include a resistor circuit for providing a component of the second transfer function in a first frequency range and a component of the second transfer function in a second frequency range, and each circuit further includes a frequency-dependent connectable circuit including a frequency-dependent component and a resistor.

[0033] For example, a connectable circuit takes the form of a capacitor and a resistor connected in series. In this case, the capacitance of the capacitor is selected such that the capacitor is conductive only at frequencies within a second frequency range, and thus the connectable circuit is connected frequency-dependently at frequencies within the second frequency range.

[0034] According to another embodiment, the second circuit of the amplifier circuit of the driving unit and the second circuit of the amplifier circuit of the voltage measuring unit are formed by a single circuit. This advantageously saves component parts and thus saves space in the optical system.

[0035] The voltage measurement unit can also be connected to different channels or different actuators via a multiplexer. In this case, while it is impossible to measure all actuators simultaneously, fewer circuits are required.

[0036] According to a second embodiment, an optical system comprising a plurality of drivable optical elements is proposed, an actuator is assigned to each of the said number of drivable optical elements, and a driving device for driving an actuator according to the first embodiment or one of the embodiments of the first embodiment is assigned to each actuator.

[0037] The optical system, in particular, includes a micro-mirror array and / or a micro-lens element array having a number of optical elements that can be driven independently of each other.

[0038] In an embodiment, an actuator group may be defined, and the same driving device is assigned to all actuators in the group.

[0039] According to the embodiment, the optical system is in the form of an illumination optical unit of a lithography device or a projection optical unit.

[0040] According to another embodiment, the optical system has a vacuum housing, and a driveable optical element, an assigned actuator, and a driving device are arranged within the vacuum housing.

[0041] According to a third aspect, a lithography device having an optical system according to a second aspect or an optical system according to one of the embodiments of the second aspect is proposed.

[0042] The lithography device is, for example, an EUV lithography device in which the wavelength range of the working light is 0.1 nm to 30 nm, or a DUV lithography device in which the wavelength range of the working light is 30 nm to 250 nm.

[0043] In this example, the singular expression should not be understood as being limited to exactly one element. Rather, multiple elements, such as two, three, or more, may also be provided. Any other number used herein should not be understood as implying a limitation on the precisely specified number of elements. Rather, unless otherwise specified, numerical variations are possible in both upward and downward directions.

[0044] Additional possible embodiments of the present invention also include combinations of features or embodiments not explicitly mentioned above or below in connection with exemplary embodiments. In such cases, those skilled in the art will also add individual aspects as improvements or supplements to each basic form of the present invention.

[0045] Further advantageous configurations and aspects of the present invention are the subject of the dependent claims and also of the exemplary embodiments of the present invention described below. The present invention will be described in more detail below based on preferred embodiments with reference to the accompanying drawings. Brief explanation of the drawing

[0046] FIG. 1 illustrates a schematic meridional cross-section of a projection exposure apparatus for EUV projection lithography; FIG. 2 illustrates a schematic diagram of an embodiment of an optical system; FIG. 3 illustrates a schematic block diagram of an embodiment of a driving device for driving and measuring an actuator for driving an optical element in an optical system; FIG. 4 illustrates the block diagram of FIG. 3 with the transfer function plotted; FIG. 5 illustrates a schematic block diagram having an embodiment of a driving unit and a voltage measuring unit of a driving device for driving and measuring an actuator for driving an optical element in an optical system. Unless otherwise specified, identical or functionally identical elements in the drawings are given the same reference numerals. Additionally, it should be noted that the examples in the drawings are not necessarily faithful to actual scale. Specific details for implementing the invention

[0047] FIG. 1 illustrates an embodiment of a projection exposure apparatus (1) (lithography apparatus), particularly an EUV lithography apparatus. One embodiment of the illumination system (2) of the projection exposure apparatus (1) has, in addition to a light source or radiation source (3), an illumination optical unit (4) for illuminating an object field (5) on an object plane (6). In an alternative embodiment, the light source (3) may 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).

[0048] A reticle (7) arranged in an object field (5) is exposed. The reticle (7) is held by a reticle holder (8). The reticle holder (8) can be displaced, particularly in the scanning direction, by a reticle displacement drive device (9).

[0049] FIG. 1 illustrates a Cartesian coordinate system having an x ​​direction (x), a y direction (y), and a z direction (z) for illustrative purposes. The x direction (x) extends orthogonally to the drawing plane. The y direction (y) extends horizontally, and the z direction (z) extends vertically. The scanning direction of FIG. 1 extends along the y direction (y). The z direction (z) extends orthogonally to the object plane (6).

[0050] The projection exposure device (1) includes a projection optical unit (10). The projection optical unit (10) serves to image an object field (5) into an image field (11) of an image plane (12). The image plane (12) extends 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.

[0051] The structure on the reticle (7) is imaged onto the photosensitive layer of the wafer (13) arranged in the area of ​​the image field (11) of the image plane (12). The wafer (13) is held by a wafer holder (14). The wafer holder (14) can be displaced by a wafer displacement drive device (15), particularly along the y-direction. Displacing the reticle (7) first through the reticle displacement drive device (9) and displacing the wafer (13) second through the wafer displacement drive device (15) can be implemented to be mutually synchronized.

[0052] The light source (3) is an EUV radiation source. The light source (3) emits EUV radiation (16), which is specifically referred to as radiation, illumination radiation, or illumination light as used below. Specifically, the radiation (16) used has a wavelength in the range of 5 nm to 30 nm. The light source (3) may be a plasma source, for example, an LPP (abbreviation: laser produced plasma) source or a DPP (abbreviation: gas-discharge produced plasma) source. It may also be a synchrotron-based radiation source. The light source (3) may be a FEL (abbreviation: free-electron laser).

[0053] Illuminating radiation (16) from a light source (3) is focused by a collector (17). The collector (17) may be a collector having one or more elliptical and / or hyperbolic reflective surfaces. At least one reflective surface of the collector (17) may collide with the illuminating radiation (16) at a grazing incidence (abbreviated: GI), i.e., an angle of incidence greater than 45°, or at a normal incidence (abbreviated: NI), i.e., an angle of incidence less than 45°. The collector (17) may be structured and / or coated to optimize reflectivity for the radiation used on one hand, and to suppress external light on the other.

[0054] Downstream of the collector (17), the illumination radiation (16) propagates through the intermediate focus at the intermediate focal plane (18). The intermediate focal plane (18) may represent a separation between the radiation source module having the light source (3) and the collector (17) and the illumination optical unit (4).

[0055] The illumination optical unit (4) includes a deflection mirror (19) and a first facet mirror (20) arranged downstream therefrom in the beam path. The deflection mirror (19) may be a planar deflection mirror, or alternatively, a mirror having a beam influence effect beyond a pure deflection effect. Alternatively or additionally, the deflection mirror (19) may be in the form of a spectral filter that separates the used light wavelength of the illumination radiation (16) from the external light of a wavelength that deviates from it. When the first facet mirror (20) is arranged in the plane of the illumination optical unit (4) that is optically conjugated to the object plane (6) as a field plane, it is also referred to as a field facet mirror. The first facet mirror (20) includes a plurality of individual first facets (21), which may also be referred to as field facets. In FIG. 1, only some of these first facets (21) are shown as examples.

[0056] The first facet (21) may be embodied as a macroscopic facet, in particular as a rectangular facet or an arched edge contour or a facet having an edge contour of part of a circle. The first facet (21) may be embodied as a flat facet or alternatively as a convex or concave curved facet.

[0057] For example, as known from DE 10 2008 009 600 A1, the first facet (21) itself may also be composed of a plurality of individual mirrors, in particular a plurality of micro-mirrors, in each case. In particular, the first facet mirror (20) may be embodied as a microelectromechanical system (MEMS system). For details, refer to DE 10 2008 009 600 A1.

[0058] Between the collector (17) and the deflection mirror (19), the illumination radiation (16) travels horizontally, that is, along the y direction (y).

[0059] In the beam path of the illumination optical unit (4), the second faceted mirror (22) is arranged downstream of the first faceted mirror (20). If the second faceted mirror (22) is arranged in the pupil plane of the illumination optical unit (4), it is also referred to as a pupil faceted mirror. The second faceted mirror (22) may also be arranged at a distance from the pupil plane of the illumination optical unit (4). In this case, the combination of the first faceted mirror (20) and the second faceted 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 6,573,978.

[0060] The second facet mirror (22) includes a plurality of second facets (23). In the case of a pupil facet mirror, the second facet (23) is also referred to as a pupil facet.

[0061] The second facet (23) may likewise be a macroscopic facet that may have, for example, circular, rectangular, or hexagonal boundaries, or alternatively be a facet composed of micro-mirrors. In this regard, reference likewise is made to DE 10 2008 009 600 A1.

[0062] The second facet (23) may have a flat reflective surface, or alternatively, a reflective surface having a convex or concave curvature.

[0063] Therefore, the illumination optical unit (4) forms a double faceted system. This basic principle is also referred to as a fly eye condenser (or integrator).

[0064] It may be advantageous not to arrange the second faceted mirror (22) exactly on a plane that is optically conjugated to the pupil plane of the projection optical unit (10). In particular, the second faceted mirror (22) may be arranged to be tilted with respect to the pupil plane of the projection optical unit (10), for example, as described in DE 10 2017 220 586 A1.

[0065] With the help of the second facet mirror (22), individual first facets (21) are imaged into the object field (5). The second facet mirror (22) is the final beam-forming mirror, or actually the final mirror for the illumination radiation (16) upstream of the beam path of the object field (5).

[0066] In another embodiment (not shown) of the illumination optical unit (4), a transfer optical unit, which contributes particularly to imaging the first facet (21) into the object field (5), may be arranged in the beam path between the second facet mirror (22) and the object field (5). The transfer optical unit may have exactly one mirror or, alternatively, two or more mirrors arranged back-and-forth with each other in the beam path of the illumination optical unit (4). The transfer optical unit may specifically include one or two vertical incident mirrors (NI mirrors) and / or one or two grazing incident mirrors (GI mirrors).

[0067] In the embodiment illustrated in FIG. 1, the illumination optical unit (4) has exactly three mirrors downstream of the collector (17), specifically a deflection mirror (19), a first faceted mirror (20), and a second faceted mirror (22).

[0068] In another embodiment of the illumination optical unit (4), since the deflection mirror (19) is also not required, the illumination optical unit (4) may have exactly two mirrors, specifically a first faceted mirror (20) and a second faceted mirror (22), downstream of the collector (17).

[0069] Imaging the first facet (21) into the object plane (6) by the second facet (23) or by using the second facet (23) and a transfer optical unit is often only approximate imaging.

[0070] The projection optical unit (10) includes a plurality of mirrors (Mi) numbered in succession according to their arrangement in the beam path of the projection exposure device (1).

[0071] In the example illustrated in FIG. 1, the projection optical unit (10) comprises six mirrors (M1 to M6). Alternatives having four, eight, ten, twelve, or any other number of mirrors (Mi) are similarly possible. The projection optical unit (10) is a double-shielded optical unit. The second-to-last mirror (M5) and the last mirror (M6) each have a passage opening for illumination radiation (16). The projection optical unit (10) has an image-side aperture number greater than 0.5 and can also be greater than 0.6, and may be, for example, 0.7 or 0.75.

[0072] The reflective surface of the mirror (Mi) can be embodied as a freeform surface without a rotational symmetry axis. Alternatively, the reflective surface of the mirror (Mi) can be designed as an aspherical surface having exactly one rotational symmetry axis of the reflective surface shape. Like the mirror of the illumination optical unit (4), the mirror (Mi) can have a high-reflection coating against illumination radiation (16). Such a coating can be designed as a multilayer coating, in particular, with alternating layers of molybdenum and silicon.

[0073] The projection optical unit (10) has a large object-image offset in the y direction (y) between the y coordinate of the center of the object field (5) and the y coordinate of the center of the image field (11). This object-image offset in the y direction (y) may be approximately the same size as the z distance between the object plane (6) and the image plane (12).

[0074] In particular, the projection optical unit (10) may have an anamorphic shape. In particular, the projection optical unit has different imaging scales (βx, βy) in the x and y directions (x, y). The two imaging scales (βx, βy) of the projection optical unit (10) are preferably (βx, βy) = (+ / -0.25, + / -0.125). A positive imaging scale (β) signifies imaging without image inversion. A negative sign of the imaging scale (β) signifies imaging with image inversion.

[0075] As a result, the projection optical unit (10) causes a size reduction of 4:1 in the x direction (x), that is, in a direction orthogonal to the scanning direction.

[0076] The projection optical unit (10) causes a size reduction of 8:1 in the y direction (y), that is, in the scanning direction.

[0077] Other imaging scales are also possible. Imaging scales having the same sign and the same absolute value in the x direction (x) and the y direction (y), for example, with an absolute value of 0.125 or 0.25, are also possible.

[0078] The number of intermediate image planes in the x direction (x) and y direction (y) in the beam path between the object field (5) and the image field (11) may be the same or different depending on the embodiment of the projection optical unit (10). An example of a projection optical unit having different numbers of such intermediate images in the x and y directions (x, y) is known from US 2018 / 0074303 A1.

[0079] In each case, one of the second facets (23) is assigned to exactly one of the first facets (21) to form a lighting channel for illuminating the object field (5). This can produce lighting based on the Köhler principle in particular. The far field is decomposed into multiple object fields (5) with the help of the first facet (21). The first facet (21) generates multiple images of intermediate focus on the second facet (23) each assigned to it.

[0080] Through the assigned second facet (23), the first facet (21) is imaged onto the reticle (7) in a manner that overlaps each other to illuminate the object field (5) in each case. The illumination of the object field (5) is particularly homogeneous as much as possible. A uniformity error of less than 2% is desirable. Field uniformity can be achieved through the overlap of different illumination channels.

[0081] The illumination of the entry pupil of the projection optical unit (10) can be geometrically defined by an arrangement of second facets (23). The intensity distribution of the entry pupil of the projection optical unit (10) can be set by selecting a subset of the second facets (23), in particular, an illumination channel that guides the light. This intensity distribution is also referred to as illumination setting or illumination pupil filling.

[0082] Likewise, desirable pupil uniformity in the section area of ​​the lighting pupil of the lighting optical unit (4) that is illuminated in a defined manner can be achieved by redistributing the lighting channels.

[0083] Further aspects and details regarding the illumination of the object field (5) and, in particular, the entry pupil of the projection optical unit (10) are described below.

[0084] The projection optical unit (10) may have a hollow entry cavity, in particular. The latter may be accessible. It may also be inaccessible.

[0085] The entry pupil of the projection optical unit (10) often cannot be accurately illuminated using the second faceted mirror (22). In the case of imaging of the projection optical unit (10) telecentrically imaging the center of the second faceted mirror (22) on the wafer (13), the aperture rays often do not intersect at a single point. However, it is possible to find an area where the spacing between the determined pairs of aperture rays is minimized. This area represents the entry pupil or an area of ​​real space conjugated thereto. In particular, this area has a finite curvature.

[0086] The projection optical unit (10) may have different orientations of the entry pupil for the tangential beam path and the sagittal beam path. In this case, the imaging element, specifically the optical component part of the transmission optical unit, must be provided between the second faceted mirror (22) and the reticle (7). With the help of this optical element, the different orientations of the tangential entry pupil and the sagittal entry pupil can be taken into account.

[0087] In the arrangement of components of the illumination optical unit (4) illustrated in FIG. 1, the second faceted mirror (22) is arranged in an area conjugated to the entry pupil of the projection optical unit (10). The first faceted mirror (20) is arranged to be tilted with respect to the object plane (6). The first faceted mirror (20) is arranged to be tilted with respect to the arrangement plane defined by the deflection mirror (19). The first faceted mirror (20) is arranged to be tilted with respect to the arrangement plane defined by the second faceted mirror (22).

[0088] FIG. 2 illustrates a schematic diagram of an embodiment of an optical system (300) for a lithography device or a projection exposure device (1), for example, as shown in FIG. 1. Additionally, the optical system (300) of FIG. 2 can also be used in a DUV lithography device, for example.

[0089] The optical system (300) of FIG. 2 has a plurality of drivable optical elements (310). The optical system (300) is designed here as a micro-mirror array, and the optical elements (310) are micro-mirrors. Each micro-mirror (310) is drivable via an assigned actuator (200). For example, each micro-mirror (310) may be tilted about two axes and / or displaced along one, two, or three spatial axes via an assigned actuator (200). For clarity, only the reference numeral of the top row of these elements is shown.

[0090] The driving device (100) drives each actuator (200) using, for example, a driving voltage (AS). This sets the position of each micro mirror (310). The driving device (100) is described with particular reference to FIGS. 3 through 5.

[0091] FIG. 3 illustrates a schematic block diagram of an embodiment of a driving device (100) for driving and measuring an actuator (200) for driving an optical element (310) in an optical system (300). To this end, FIG. 4 illustrates the block diagram of FIG. 3 with transfer functions (G1 to G4) plotted.

[0092] The driving device (100) according to FIGS. 3 and 4 includes a driving unit (110) for driving an actuator (200), a voltage measuring unit (120) coupled to the actuator (200), a current measuring unit (130) coupled to the actuator (200), and a determining unit (140) coupled to the voltage measuring unit (120) and the current measuring unit (130).

[0093] The driving unit (110) has a frequency-dependent first transfer function (G1) (see FIG. 4), which is configured to amplify a time-dependent AC voltage signal (W) using at least a first frequency range (F1) and a second frequency range (F2) to form a driving signal (AS) for an actuator (200), so that the first frequency range (F1) experiences a higher gain compared to the second frequency range (F2) by a certain factor. As illustrated in an exemplary manner in FIG. 4, the first transfer function (G1) has a first frequency range (F1) having a low frequency and a second frequency range (F2) having a high frequency. For example, the first frequency range is located at 0 Hz to 1 kHz, preferably 0 Hz to 500 Hz, more preferably 0 Hz to 300 Hz. The second frequency range (F2) is preferably located at 5 kHz to 100 kHz, more preferably at 10 kHz to 100 kHz, and particularly preferably at 10 kHz to 60 kHz. The specific gain factor is particularly 100 to 2000, preferably 500 to 1500, and more preferably 800 to 1200.

[0094] A voltage measuring unit (120) is configured to convolve a time-dependent voltage (u) of an actuator (200) in the time domain with a second transfer function (G2) based on the reciprocal of a first transfer function (G1), and then measure the time-dependent voltage to provide a measured voltage (U). To this end, FIG. 4 illustrates a second transfer function (G2) of the voltage measuring unit (120), said second transfer function is based on the reciprocal of the first transfer function (G1), as indicated by a comparison between the transfer functions (G2 and G1). As illustrated by the comparison between the transfer functions (G1 and G2) in FIG. 4, the first transfer function (G1) induces high gain in the frequency range (F1), whereas the second transfer function (G2) induces low gain in the first frequency range (F1). In contrast, the first transfer function (G1) produces a low gain in the second frequency range (F2), whereas the second transfer function (G2) produces a higher gain in the second frequency range (F2).

[0095] The components of the driving signal (AS) in the first frequency range (F1) serve to drive the actuator (200). Consequently, the first frequency range (F1) experiences high gain to properly drive the actuator (200). Prior to each measurement, i.e., prior to voltage measurement and current measurement, the first frequency range (F1) is attenuated and the second frequency range (F2) is amplified, so that high resolution is provided for measuring the actuator (200) in the second frequency range (F2).

[0096] In this case, the second transfer function (G2) provides high resolution in the second frequency range (F2) important for measurement, thereby providing high requirements in terms of accuracy.

[0097] The current measuring unit (130) is configured to convolve the time-dependent current (i) of the actuator (200) in the time domain with a third transfer function (G3) based on the reciprocal of the first transfer function (G1), and then measure the time-dependent current to provide a measured current (I). Convolution in the time domain corresponds to multiplication in the frequency range.

[0098] To this end, FIG. 4 illustrates a third transfer function (G3). In a manner similar or identical to the second transfer function (G2), the third transfer function (G3) produces a low gain in the first frequency range (F1) and a higher gain in the second frequency range (F2).

[0099] A determination device (140) coupled to a voltage measurement unit (120) and a current measurement unit (130) is configured to determine the impedance (Z) or impedance behavior of an actuator (200) based on a provided measured voltage (U) and a provided measured current (I).

[0100] To this end, the transfer function (G4) for the impedance (Z) of the actuator (200) according to FIG. 4 shows high resolution in a second frequency band (F2), which can also be referred to as a measurement frequency band.

[0101] Furthermore, FIG. 5 illustrates a schematic block diagram having an embodiment of a driving unit (110) and a voltage measuring unit (120) of a driving device (100) for driving and measuring an actuator (200) for driving an optical element (310) in an optical system (300). An example of the driving device (100) is illustrated in FIG. 3 and FIG. 4.

[0102] The driving unit (110) of FIG. 5 includes an amplifier circuit (111), in particular a differential amplifier.

[0103] The amplifier circuit (111) of the driving unit (110) includes an input node (K1) for supplying an AC voltage signal (W) (see also FIG. 3 and FIG. 4), an output node (K2) for providing a driving voltage (AS) for an actuator (200) (see also FIG. 2 to FIG. 4), and an operational amplifier (112) coupled between the input node (K1) and the output node (K2). To provide a first transfer function (G1) (see FIG. 4), a first circuit (113) is coupled to the input node (K1), the negative supply voltage (VSS) of the driving device (100), and the non-inverting input of the operational amplifier (112), and a second circuit (114) is coupled to the inverting input of the operational amplifier (112), ground (GND), and the output node (K2).

[0104] The first circuit (113) and the second circuit (114) each have a resistor circuit (115, 116) for controlling gain in a first frequency range (F1) and for controlling gain in a second frequency range (F2) according to a first transfer function (G1), and each circuit additionally has a frequency-dependent connectable circuit (117, 118) including frequency-dependent component parts (C1, C2) and resistors (R5, R6).

[0105] The resistor circuit (115) of the first circuit (113) includes a resistor (R3) connected between the input node (K1) and the non-inverting input of the operational amplifier (112), and a resistor (R4) connected between the negative supply voltage (VSS) and the non-inverting input of the operational amplifier (112). Additionally, the connectable circuit (117) of the first circuit (113) includes a capacitor (C1) and a resistor (R5) connected in series. In this case, the capacitance of the capacitor (C1) is selected such that the capacitor (C1) is conductive only at a frequency of the second frequency range (F2), and thus the circuit (117) is connected frequency-dependently at a frequency of the second frequency range (F2).

[0106] The resistor circuit (116) of the second circuit (114) includes a resistor (R1) connected between ground (GND) and the inverting input of the operational amplifier (112), and a resistor (R2) connected between the inverting input of the operational amplifier (112) and the output node (K2). The connectable circuit (118) of the second circuit (114) has a capacitor (C2) and a resistor (R6) connected in series.

[0107] The connectable circuit (118) has the same function as the connectable circuit (117). In this case, the capacitance of the capacitor (C2) is selected such that the capacitor (C2) is conductive only at a frequency in the second frequency range, and thus the circuit (118) is connected frequency-dependently at a frequency in the second frequency range.

[0108] This completes the detailed description of the driving unit (110) according to FIG. 5. Now, attention is paid to the detailed description of the voltage measuring unit (120) according to FIG. 5. The voltage measuring unit (120) of FIG. 5 includes an amplifier circuit (121), in particular a differential amplifier.

[0109] The amplifier circuit (121) of the voltage measurement unit (120) includes an input node (K3) that is coupled to the output node (K2) of the amplifier circuit (111) of the driving unit (110) and serves to receive the time-dependent voltage (u) of the actuator (200), an output node (K4) for providing the measured voltage (U), and an operational amplifier (122) coupled between the input node (K3) and the output node (K4). To provide a second transfer function (G2), the first circuit (123) is coupled to the output node (K4), the negative supply voltage (VSS) of the driving device (100), and the inverting input of the operational amplifier (122), and the second circuit (124) is coupled to the input node (K3), the non-inverting input of the operational amplifier (122), and ground (GND). In the embodiment according to FIG. 5, the second circuit (114) of the amplifier circuit (111) of the driving unit (110) and the second circuit (124) of the amplifier circuit (121) of the voltage measuring unit (120) are formed by a single circuit, that is, they are identical. This advantageously saves components, and in particular saves space for the optical system (300).

[0110] As illustrated in FIG. 5, the first circuit (123) and the second circuit (124) of the amplifier circuit (121) of the voltage measuring unit (120) each have a resistor circuit (125, 116) that provides a portion of the second transfer function (G2) in a first frequency range (F1) and a portion of the second transfer function (G2) in a second frequency range (F2), and each circuit additionally has a frequency-dependently connectable circuit (127, 118).

[0111] Since the second circuit (124) of the voltage measuring unit (120) corresponds to the second circuit (114) of the driving unit (110), to avoid repetition, only the first circuit (123) of the amplifier circuit (121) of the voltage measuring unit (120) is described in detail below. The first circuit (123) has a resistor circuit (125) comprising a resistor (R1) coupled between the output node (K4) and the inverting input of the operational amplifier (122), and a resistor (R2) coupled between the inverting input of the operational amplifier (122) and the negative supply voltage (VSS). The resistance values ​​of the resistors (R1, R2) of the resistor circuit (116) and the resistance values ​​of the resistors (R1, R2) of the resistor circuit (125) may be the same or different depending on the application.

[0112] The connectable circuit (127) of the first circuit (123) includes a capacitor (C3) and a resistor (R7) connected in series between the inverting input of the operational amplifier (122) and the negative supply voltage (VSS). In this case, the capacitance of the capacitor (C3) is selected so that the capacitor (C3) is conductive only at a frequency of the second frequency range (F2).

[0113] Although the present invention has been described with reference to exemplary embodiments, it can be modified in various ways. Explanation of the symbols

[0114] 1 Projection exposure device 2 lighting systems 3 light sources 4 lighting optical units 5 Object Field 6 Object Plane 7 Reticle 8 Reticle Holders 9 Reticle Displacement Drive Unit 10 Projection Optical Units 11 Image Field 12 image plane 13 wafers 14 wafer holders 15 Wafer Displacement Driving Device 16 Illuminating radiation 17 Collectors 18 intermediate focus plane 19 Biased Mirror 20 First Faceted Mirror 21 First Facet 22 Second Faceted Mirror 23 Second Facet 100 driving devices 110 drive unit 111 Differential Amplifier 112 operational amplifier 113 First circuit 114 Second circuit 115 Resistance Circuit 116 Resistance Circuit 117 Connectable circuits 118 connectable circuits 120 voltage measuring unit 121 Differential Amplifier 122 Operational Amplifier 123 First circuit 124 Second circuit 125 resistor circuit 127 Connectable Circuits 130 Current Measurement Unit 200 actuators 300 Optical System 310 optical element Amplitude AS driving voltage C1 capacitor C2 capacitor C3 capacitor f frequency F1 first frequency range F2 Second frequency range G1 transfer function G2 transfer function G3 transfer function G4 transfer function GND ground I measured current i Actuator current K1 input node K2 output node K3 input node K4 output node M1 mirror M2 mirror M3 mirror M4 mirror M5 mirror M6 mirror R1 resistor R2 resistor R3 resistor R4 resistor R5 resistor R6 resistor R7 resistor U measured voltage voltage of the u actuator VSS negative supply voltage W AC voltage signal Z impedance

Claims

Claim 1 A driving device (100) for driving and measuring an actuator (200) for driving an optical element (310) of an optical system (300), and a driving unit (110) having a frequency-dependent first transfer function (G1), wherein the transfer function is configured to amplify a time-dependent AC voltage signal (W) using at least a first frequency range (F1) and a second frequency range (F2) to form a driving voltage (AS) for the actuator (200), and accordingly, the first frequency range (F1) experiences a higher gain compared to the second frequency range (F2) by a specific factor, and a voltage measuring unit (120) for providing a measurement voltage (U), wherein in the time domain, the time-dependent voltage (u) of the actuator (200) is convolved with a second transfer function (G2) based on the reciprocal of the first transfer function (G1), and subsequently the time-dependent voltage A driving device comprising a voltage measuring unit configured to measure and provide a measured voltage (U), and a current measuring unit (130) configured to provide a measured current (I), wherein the current measuring unit convolves a time-dependent current (i) of an actuator (200) in the time domain with a third transfer function (G3) based on the reciprocal of a first transfer function (G1), and then measures the time-dependent current to provide a measured current (I). Claim 2 A driving device according to claim 1, further comprising a determining unit (140) coupled to a voltage measuring unit (120) and a current measuring unit (130) and configured to determine the impedance (Z) of an actuator (200) based on a provided measured voltage (U) and a provided measured current (I). Claim 3 A driving device according to claim 1 or 2, wherein the first frequency range (F1) is located at 0 Hz to 1 kHz or 0 Hz to 500 Hz or 0 Hz to 300 Hz, and the second frequency range (F2) is located at 5 kHz to 100 kHz or 10 kHz to 100 kHz or 10 kHz to 60 kHz. Claim 4 A driving device according to claim 1 or 2, wherein the specific factor is 100 to 2000 or 500 to 1500 or 800 to 1200. Claim 5 In claim 1 or 2, the driving unit (110) is a driving device having an amplifier circuit (111) or a differential amplifier. Claim 6 In claim 5, the amplifier circuit (111) of the driving unit (110) has an input node (K1) for supplying an AC voltage signal (W), an output node (K2) for providing a driving voltage (AS) for an actuator (200), and an operational amplifier (112) coupled between the input node (K1) and the output node (K2), and to provide a first transfer function (G1), a first circuit (113) is coupled to the input node (K1), the negative supply voltage (VSS) of the driving device (100), and the non-inverting input of the operational amplifier (112), and a second circuit (114) is coupled to the inverting input of the operational amplifier (112), ground (GND), and the output node (K2), a driving device. Claim 7 A driving device according to claim 6, wherein the first circuit (113) and the second circuit (114) each have a resistor circuit (115, 116) for adjusting gain in a first frequency range (F1) and for adjusting gain in a second frequency range (F2), and each circuit further has a frequency-dependent connectable circuit (117, 118) including frequency-dependent component parts (C1, C2) and resistors (R5, R6). Claim 8 In claim 1 or 2, the voltage measuring unit (120) is a driving device having an amplifier circuit (121) or a differential amplifier. Claim 9 In claim 8, the amplifier circuit (121) of the voltage measurement unit (120) is coupled to the output node (K2) of the amplifier circuit (111) of the driving unit (110) and has an input node (K3) that serves to receive a time-dependent voltage (u) of the actuator (200), an output node (K4) for providing a measurement voltage (U), and an operational amplifier (112) coupled between the input node (K3) and the output node (K4), and to provide a second transfer function (G2), the first circuit (123) is coupled to the output node (K4), the negative supply voltage (VSS) of the driving device (100) and the inverting input of the operational amplifier (122), and the second circuit (124) is coupled to the input node (K3), the non-inverting input of the operational amplifier (122) and ground (GND). Claim 10 A driving device according to claim 9, wherein the first circuit (123) and the second circuit (124) each have a resistor circuit (125, 116) for providing a component of the second transfer function (G2) in a first frequency range (F1) and a component of the second transfer function (G2) in a second frequency range (F2), and each circuit further has a frequency-dependent connectable circuit (127, 118) including frequency-dependent component parts (C3, C2) and resistors (R7, R6). Claim 11 In claim 9, the second circuit (114) of the amplifier circuit (111) of the driving unit (110) and the second circuit (124) of the amplifier circuit (121) of the voltage measuring unit (120) are formed by a single circuit, the driving device. Claim 12 An optical system (300) comprising a plurality of drivable optical elements (310), wherein an actuator (200) is assigned to each of the number of drivable optical elements (310), and a driving device (100) for driving the actuator (200) according to claim 1 or 2 is assigned to each actuator (200). Claim 13 In paragraph 12, the optical system (300) is an optical system in the form of an illumination optical unit (4) of a lithography device (1) or a projection optical unit (10). Claim 14 A lithography device (1) including an optical system (300) according to paragraph 12.

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