Optical device and lithographic apparatus

Abstract

An optical device (200) for a lithographic apparatus (100A, 100B), comprising: a microsystem (202) having a mirror array (204), wherein respective mirrors (206) of the mirror array (204) are arranged to reflect operating light (108A, 108B) of the lithographic apparatus (100A, 100B) at their front sides (208) and also to reflect measurement beams (L, 224) at their rear sides (220); one or more radiation sources (222), arranged outside the microsystem (202) and arranged to provide respective measurement beams (L, 224); and one or more sensor units (230, 804, 1200), arranged to sense the tilt angles (α) of respective mirrors (206) based on the respective reflected measurement beams (L’, 224’).

Description

Field of the Invention

[0001] The present invention relates to an optical device and a lithographic apparatus.

[0002] Cross-reference to Related Applications

[0003] The content of priority application DE 10 2019 204 165.5 is hereby incorporated by reference in its entirety. Background Art

[0004] Microlithography is used to produce microstructured components, such as integrated circuits. The microlithography process is performed using a lithographic apparatus having an illumination system and a projection system. In this case, an image of a mask (mask blank) illuminated by the illumination system is projected onto a substrate, such as a silicon wafer coated with a photosensitive layer (photoresist) and arranged in the image plane of the projection system, in order to transfer the mask structure onto the photosensitive coating of the substrate.

[0005] In lithographic apparatuses designed for the EUV range (i.e., at a wavelength of, for example, approximately 13 nanometers), mirrors are used as optical components of the imaging process due to the lack of suitable transmissive refractive materials.

[0006] It is known to use faceted mirrors in the illumination system in order to shape EUV light appropriately and direct it to the mask. Such faceted mirrors comprise a plurality of individual mirrors.

[0007] In order to be able to fabricate ever-smaller structures on a substrate (such as a silicon wafer), it is desirable to increase the number of individual mirrors while reducing their size. This can be achieved by producing individual mirrors as microsystems (also known as MEMS or microelectromechanical systems).

[0008] Each individual mirror can be tilted about two mutually perpendicular axes by an actuator. In order to be able to control the corresponding tilt angles appropriately, sensors for sensing the respective actual tilt angles are provided. In this regard, it is known to use capacitive sensors.

[0009] However, especially in EUV systems, it is difficult to achieve a signal-to-noise ratio suitable for controlling the tilt angles. This is because the EUV radiation source generates groups of EUV light pulses (also known as pulse trains). The pulse trains occur at a frequency of approximately 50 to 100 hertz. The pulses in the respective pulse trains have a frequency of approximately 100 kilohertz. The resulting electric fields generate unwanted interference in the frequency range relevant to the control using capacitive sensors.

[0010] In addition, there is the fact that many other components in the vicinity of the sensor operate capacitively. The production of the faceted mirrors of the microsystem and the resulting effect of bringing the components closer to each other further unfavorably increases the capacitive interaction. SUMMARY OF THE INVENTION

[0011] Against this background, it is an object of the present invention to provide an improved optical device and an improved lithography apparatus.

[0012] Accordingly, there is provided an optical device for a lithography apparatus, comprising:

[0013] a microsystem having a mirror array, wherein respective mirrors of the mirror array are arranged to reflect the working light of the lithography apparatus at their front sides and also to reflect a measurement beam at their rear sides,

[0014] one or more radiation sources arranged to provide respective measurement beams, and

[0015] one or more sensor units arranged to sense the tilt angles of respective mirrors based on the respective reflected measurement beams.

[0016] The fact that the tilt angle is sensed by means of the measurement beam means that the tilt angle is sensed optically rather than capacitively and is sensed accordingly in a different (control) domain. The signal-to-noise ratio is thus improved and the sensitivity to electrical interference is reduced. In addition, a higher accuracy can be obtained with an optical measurement system compared to a capacitive measurement system, which is particularly advantageous for the miniaturized structure of the microsystem. Finally, the optical system can also be calibrated more easily.

[0017] The device is particularly suitable for a lithography apparatus, in particular an EUV or DUV lithography apparatus. However, the device can also be suitably configured for a measurement system for optical measurement of a lithography apparatus or some other optical system.

[0018] The microsystem is here understood to mean a system in which the dimensions (maximum edge length) of the individual components are between 0.001 mm and 5 mm. Another characteristic of microsystems is that they can be produced by semiconductor production methods. This particularly includes etching and spark erosion as well as the use of thin film techniques (such as sputtering).

[0019] The mirror array is understood to mean a micro-mirror array. Each micro-mirror can for example have a mirror area of less than or equal to 5 mm 2 、1 mm 2 or 0.5 mm 2 . For example, a mirror array can have 32x32 or 64x64 mirrors.

[0020] The corresponding mirror is preferably arranged to reflect the working light of the lithographic apparatus (or other light within the optical system of the apparatus) at its front side. The working light refers to the light related to the lithographic apparatus and generated by the structure on the substrate (especially the wafer). This may be EUV or DUV light. In the case of some other optical systems, the working light serves the main purpose of the optical system. For example, if the optical system is formed as a measurement system for optical measurement of a lithographic apparatus, the working light is the corresponding light beam for optical measurement.

[0021] Furthermore, the corresponding mirror is arranged to reflect the provided measurement beam at its rear side. The reflection can occur indirectly or directly at the rear side. Specifically, the provided measurement beam can be reflected at a part of the mounting arranged at the rear side of the mirror, especially the mounting firmly connected to the rear surface of the mirror (this is an example of indirect reflection). This mounting is used for tilting the corresponding mirror to change the tilt angle. As an alternative or in addition, the light can be directly irradiated on the surface at the rear side of the mirror, that is, there is no reflection on other components (such as the mounting) arranged between the rear side and the reflective surface.

[0022] The mirrors in the mirror array can be part of a faceted mirror. The faceted mirror can be arranged in the illumination system of the lithographic apparatus.

[0023] The measurement beam can have light with a wavelength of 100 nanometers to 3000 nanometers, preferably between 380 nanometers and 800 nanometers (visible light) or between 800 nanometers and 1650 nanometers (near-infrared range).

[0024] For example, the use of light-emitting diodes (hereinafter referred to as "LEDs") or lasers, such as the continuously tunable laser from TOPTICA Photonics AG, can be considered. In an embodiment, each microsystem, mirror module or faceted mirror can be precisely provided with a radiation source.

[0025] The sensor unit or the corresponding sensor unit can be formed as a photodiode.

[0026] The tilt angle is the angle obtained when the mirror (single mirror) rotates around an axis located or substantially located within the mirror plane. Usually, two such axes that can be perpendicular to each other are provided. Accordingly, the first tilt angle and / or the second tilt angle are measured by the corresponding sensor unit.

[0027] The radiation source or the corresponding radiation source can be arranged to generate the measurement beam in a phase-modulated or frequency-modulated manner. This can make the measurement less sensitive to the noise described at the beginning.

[0028] According to one embodiment, the microsystem has a substrate on which a mirror array is arranged, wherein the respective mirrors are tiltably mounted on the substrate.

[0029] For mounting purposes, bends may be provided. In each case, the bends may be fixed on the one hand to the substrate and on the other hand to the respective mirrors, in particular being formed integrally with them. Furthermore, preferably, two or more mirrors are tiltably mounted on the same substrate (monolithic substrate). The substrate may be made of semiconductor material. The semiconductor material may include silicon and / or indium phosphide. Silicon is particularly suitable as a carrier material for electronic components, while indium phosphide is particularly suitable as a carrier material for optical components. For example, at least one conductor track for an electric current (in particular for forming an electronic integrated circuit) and / or at least one optical waveguide (in particular for forming a photonic integrated circuit) may be formed in the structure of the semiconductor material.

[0030] According to one embodiment, one or more radiation sources are provided outside the microsystem. Preferably, one or more radiation sources are additionally arranged outside the vacuum region of the device or the lithographic apparatus.

[0031] Due to defects, light-emitting diodes and lasers, which are radiation sources, often need to be replaced. Due to the fact that the radiation sources are now arranged outside the microsystem or even outside the vacuum region, access and subsequent replacement become quite easy. The vacuum region in particular refers to the region within an EUV lithographic apparatus having a beam path. This region (also called a mini-environment) must be kept particularly clean. In the vacuum region, there is a pressure of, for example, 0.1 Pa.

[0032] According to another embodiment, the microsystem has an integrated optical unit which is arranged to direct a provided measurement beam to the respective mirror.

[0033] The production of a microsystem having an integrated optical unit allows this step to be taken in the form of low-cost mass production. At the same time, the size of the integrated optical unit is very small. The integrated optical unit (also called a photonic integrated circuit) is understood in this example to be an optical unit having at least two photonic functional units (light input coupling, light output coupling, radiation source, waveguide, beam splitter, intensity or phase modulator, filter, switch, etc.) provided in or on the substrate. The functional units use light in the visible or near-infrared range and, as described above, for or to perform their respective functions. The functional units form a monolithic part with the substrate. The substrate may be the substrate on which the mirror array is arranged. In particular, the integrated optical unit is arranged to direct the provided measurement beam to the rear side of the respective mirror.

[0034] According to one embodiment, the integrated optical unit is arranged to direct the respectively reflected measurement beams or signals generated based on the respectively reflected measurement beams to one or more sensor units.

[0035] For this purpose, the integrated optical unit preferably has at least one optical waveguide that directs the reflected measurement beam or the generated signal to one or more sensor units. In particular, the signal can also be generated based on the respectively provided measurement beams. For example, the signal can be the time difference between the emission of the provided measurement beam and the reception of the reflected measurement beam, or a signal representing this time difference. This time difference can in particular be determined by measuring the wavelength difference between the provided measurement beam (with a time-varying wavelength) and the reflected measurement beam, as will be explained in more detail below for the FMCW-LIDAR method. The signal can in particular be an interference signal between the provided measurement beam and the reflected measurement beam.

[0036] According to another embodiment, the microsystem has an integrated circuit comprising one or more sensor units.

[0037] The sensor units can advantageously be produced in a cost-effective and space-saving manner as part of the integrated circuit. The integration of one or more sensor units in the microsystem also avoids data transmission to the outside, which can be advantageous in terms of data processing speed. This also allows a closed-loop control circuit to be provided within the microsystem itself, which is less susceptible to interference compared to transmitting data to an external circuit (external to the microsystem) to provide the control circuit. In the present case, the integrated circuit is understood to mean a circuit applied to a substrate comprising a semiconductor material, in particular silicon. The circuit and the substrate form a monolithic component. The substrate can be a substrate on which a mirror array is arranged.

[0038] In particular, it can be provided that the microsystem has a first substrate and a second substrate, one above the other. The first substrate contains the integrated optical unit, and the second substrate contains the integrated circuit. The mirror array can be arranged on the first substrate or the second substrate, i.e., its mirrors can be tiltably mounted on the first substrate or the second substrate. Preferably, the mirror array is arranged on the first substrate, and the second substrate is arranged below the first substrate. In this case, it is allowed for the respectively reflected measurement beams or the generated signals to pass through corresponding openings (light incidence regions) in the first substrate to reach the second substrate and be sensed by the corresponding sensor units at the second substrate.

[0039] According to another embodiment, the microsystem includes a substrate having both an integrated optical unit and an integrated circuit. That is, the substrate forms a monolithic component with the optical functional unit and the circuit.

[0040] According to another embodiment, one or more sensor units are provided outside the microsystem.

[0041] This reduces the complexity of the microsystem.

[0042] According to another embodiment, the radiation source is arranged to provide a measurement beam with a wavelength varying over time, wherein one or more filters are assigned to the respective mirrors, the filters being arranged to allow the reflected measurement beam or the signal generated thereby to pass only through a predetermined wavelength passband and reach one or more sensor units, the wavelength passbands of the filters being different from one another.

[0043] Based on the wavelength of the reflected measurement beam allowed to pass, based on the different tilt angles of the mirrors to which the filters are assigned and possibly to different mirrors, and based on the actual intensity of the reflected measurement beam allowed to pass, the tilt angle can be derived and possibly the respective mirror having this tilt angle. Preferably, the following embodiment is envisaged here: the reflected measurement beam has an intensity distribution, in particular a Gaussian intensity distribution, on the sensor unit or the light incidence area. The intensity distribution spans at least two, three, preferably four sensor units or light incidence areas. By measuring the actual intensity in each sensor unit and performing a downstream centroid determination of the (Gaussian) intensity distribution, the tilt angle of the mirror assigned to the sensor unit or the light incidence area can be determined.

[0044] According to another embodiment, the microsystem has a multiplexer which is arranged to multiplex the reflected measurement beam or the signal generated thereby onto an optical waveguide, and wherein a demultiplexer is also provided which is arranged to demultiplex the measurement beam or the signal multiplexed onto the optical waveguide (in particular outside the microsystem).

[0045] In this way, the number of optical waveguides required can be reduced. For the purpose of signal transmission, the connection of the microsystem to its surroundings is simplified accordingly. The optical waveguide is connected to a sensor unit which senses the respectively multiplexed measurement beam or the multiplexed signal. In this case, the sensor units can be easily arranged outside the microsystem and can be arranged outside the vacuum area.

[0046] According to another embodiment, one or more sensor units are arranged to sense the tilt angle of the respective mirror based on the deflection of the reflected measurement beam relative to the provided measurement beam.

[0047] For example, the sensor units are arranged at different positions in a plane below the respective mirror. Depending on the tilt angle, the reflected measurement beam or the generated signal will fall on different sensor units, depending on its centroid. The sensor units can be provided in the form of a charge-coupled device (CCD) image sensor. Since there are thus multiple sensor units, the tilt angle can be sensed relatively accurately.

[0048] According to another embodiment, the microsystem has a first substrate with a plurality of light incidence regions and a second substrate with a plurality of sensor units, wherein the plurality of light incidence regions are arranged to direct reflected measurement light beams to the plurality of sensor units.

[0049] The light incidence regions can be formed as holes, glass inserts, glass vias, and / or grating couplers in the first substrate. Alternatively, an optical waveguide can be provided in the first substrate, which optically connects the respective light incidence regions to the respective sensor units in the second substrate. The first substrate and the second substrate can be arranged one above the other and adjacent to each other. The optical waveguide can be formed as an integrated optical unit in the first substrate, and the sensor units can be formed as integrated circuits in the second substrate.

[0050] According to another embodiment, the plurality of light incidence regions include filters with different wavelength passbands.

[0051] This allows for the above multiplexing to be easily accomplished: different channels are provided by the filters. The light intensity or signal intensity of each channel can be used to determine the aforementioned centroid of the light intensity distribution and thus the tilt angle of the corresponding mirror.

[0052] According to another embodiment, one or more sensor units are arranged to sense the tilt angle of the corresponding mirror by means of a distance measurement that depends on the provided and reflected measurement light beam.

[0053] Contrary to the deflection sensing of the measurement light beam, the distance measurement is based on the measurement of the signal transit time. In different cases, the distance measurement is preferably performed between at least two (preferably three) points on the rear side of the mirror (especially the surface on the rear side of the mirror) and a reference point on the substrate. These two points may be particularly located in the corners on the rear side of the mirror. The measurement here is usually better than that performed in the middle of the rear side of the mirror because the rear side is usually occupied by the mounting for the tiltable fixation of the mirror (especially in the form of one or more bends), and thus is not easily available for the reflection of the measurement light beam. The rear side of the mirror can be roughened in the region of the corresponding points to allow the provided measurement light beam to be reflected (partially diffusely) into the designated light incidence region or the designated sensor unit.

[0054] According to another embodiment, one or more sensor units are arranged to perform a distance measurement according to the FMCW-LIDAR method.

[0055] FMCW stands for frequency-modulated continuous wave and describes the measurement of distance by comparing a frequency-modulated transmission signal with an echo reflected by the target object (here the rear side of the mirror). The frequency comparison between the transmitted signal and the echo at a given point in time is easier in terms of signal transmission than just performing the transit time measurement between the transmission of the transmitted signal and the reception of the echo.

[0056] LIDAR stands for Light Imaging Detection and Ranging, which means scanning a target object with light. Therefore, light is used here as the transmission signal to perform the FMCW method. The frequency comparison or wavelength comparison can be done, for example, by interferometry.

[0057] The FMCW-LIDAR method is understood and described in detail, for example, in the doctoral thesis "Optoelectronic Swept Lasers and Their Applications in Range Finding, 3D Imaging, and Coherent Beam Combining of Chirped Seed Amplifiers" by Arseniy Vasilev of the California Institute of Technology published in 2013.

[0058] Furthermore, a lithographic apparatus having the above-described optical device is provided.

[0059] In the current context, "a; an" does not necessarily have to be understood as being limited to one element. On the contrary, multiple elements can also be provided, for example, two, three, or more. Any other numbers used here should not be understood as being limited to the stated number of elements. Rather, numerical deviations upwards and downwards are possible, unless there is an indication to the contrary.

[0060] The embodiments and features described for the optical device apply correspondingly to the proposed lithographic apparatus, and vice versa.

[0061] Other possible embodiments of the present invention also include combinations of features or embodiments not explicitly mentioned above or below with respect to the exemplary embodiments. In this case, those skilled in the art will also add multiple individual aspects as improvements or supplements to the corresponding basic form of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Other 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. Hereinafter, the present invention will be explained in more detail with reference to the drawings, based on the preferred embodiments.

[0063] Figure 1A A schematic diagram of an exemplary embodiment of an EUV lithographic apparatus is shown;

[0064] Figure 1B A schematic diagram of an exemplary embodiment of a DUV lithographic apparatus is shown;

[0065] Figure 2A The optical device of a lithographic apparatus according to a first exemplary embodiment is schematically shown in a plan view;

[0066] Figure 2B Shows a cross-section taken from Figure 2A II-II;

[0067] Figure 3A The optical device according to the second exemplary embodiment is schematically shown in a plan view;

[0068] Figure 3B It shows a III-III cross section taken from Figure 3A ;

[0069] Figure 4 The optical device according to the third exemplary embodiment is shown in a plan view;

[0070] Figure 5A The optical device according to the fourth exemplary embodiment is schematically shown in a plan view;

[0071] Figure 5B It shows a V-V cross section taken from Figure 5A ;

[0072] Figure 6 A graph showing the relationship between wavelength and time is shown by way of example;

[0073] Figure 7 A radiation source according to an exemplary embodiment is schematically shown;

[0074] Figure 8 The optical device according to the fifth exemplary embodiment is shown in a plan view;

[0075] Figure 9A A microsystem taken from Figure 8 is schematically shown in a plan view;

[0076] Figure 9B It shows a IX-IX cross section taken from Figure 9A ;

[0077] Figure 10A A microsystem according to another exemplary embodiment is schematically shown in a plan view;

[0078] Figure 10B It shows a X-X cross section taken from Figure 10A ;

[0079] Figure 11 The parts of the FMCW-LIDAR method are shown; and

[0080] Figure 12 An arrangement taken from Figure 10A and 10B using a plurality of microsystems according to a variant is shown, and an arrangement of the FMCW-LIDAR method according to Figure 8 is shown. Also shown is an arrangement of the FMCW-LIDAR method according to Figure 11 .

[0081] Identical elements or elements having the same function are provided with the same reference numerals in the drawings, unless indicated to the contrary. It should also be noted that the illustrations in the figures are not necessarily to scale. Detailed Description

[0082] Figure 1A A schematic view of an EUV lithography apparatus 100A including a beam shaping and illumination system 102 and a projection system 104 is shown. In this case, EUV represents "extreme ultraviolet", indicating that the working wavelength of the light is between 0.1 nanometers and 30 nanometers. The beam shaping and illumination system 102 and the projection system 104 are respectively provided in a vacuum housing (not shown), and each vacuum housing is evacuated by means of a vacuum pumping device (not shown). The vacuum housing is surrounded by a machine room (not shown), in which drive devices for mechanically moving or setting optical elements are provided. In addition, an electrical controller and the like can also be provided in this machine room.

[0083] The EUV lithography apparatus 100A has an EUV radiation source 106A. A plasma source (or synchrotron) that emits radiation 108A in the EUV range (extreme ultraviolet range), that is, for example, emits radiation in a wavelength range of 5 nanometers to 20 nanometers, can be provided as the EUV radiation source 106A. In the beam shaping and illumination system 102, the EUV radiation 108A is focused, and the desired working wavelength is filtered out from the EUV radiation 108A. The EUV radiation 108A generated by the EUV radiation source 106A has a relatively low transmittance in air. Therefore, the beam guiding spaces in the beam shaping and illumination system 102 and the projection system 104 are evacuated.

[0084] Figure 1A The illustrated beam shaping and illumination system 102 has five mirrors 110, 112, 114, 116, 118. After passing through the beam shaping and illumination system 102, the EUV radiation 108A is guided onto a photomask (mask blank) 120. The photomask 120 is also formed as a reflective optical element and can be arranged outside the systems 102, 104. In addition, the EUV radiation 108A can be guided onto the photomask 120 by a mirror 122. The photomask 120 has a structure that is imaged onto a wafer 124 etc. in a reduced manner by means of the projection system 104.

[0085] The projection system 104 (also referred to as a projection lens) has six mirrors M1 to M6 for imaging the photomask 120 onto the wafer 124. In this case, the individual mirrors M1 to M6 of the projection system 104 can be arranged symmetrically with respect to the optical axis 126 of the projection system 104. It should be noted that the number of mirrors M1 to M6 of the EUV lithography apparatus 100A is not limited to the number shown. A greater or lesser number of mirrors from M1 to M6 can also be provided. In addition, the mirrors M1 to M6 are generally curved on their front sides for beam shaping.

[0086] Figure 1B A schematic view of a DUV lithography apparatus 100B is shown, which includes a beam shaping and illumination system 102 and a projection system 104. In this case, DUV stands for "deep ultraviolet" and represents a working light wavelength between 30 nanometers and 250 nanometers. As already referenced Figure 1A described, the beam shaping and illumination system 102 and the projection system 104 can be arranged in a vacuum enclosure and / or surrounded by a machine room with corresponding drive devices.

[0087] The DUV lithography apparatus 100B has a DUV radiation source 106B. For example, an ArF excimer laser that emits radiation 108B in the DUV range, such as 193 nanometers, can be provided as the DUV radiation source 106B.

[0088] Figure 1B The illustrated beam shaping and illumination system 102 directs the DUV radiation 108B onto the photomask 120. The photomask 120 is formed as a transmissive optical element and can be arranged outside the systems 102, 104. The photomask 120 has a structure that is imaged in a reduced manner onto the wafer 124, etc., by means of the projection system 104.

[0089] The projection system 104 has a plurality of lens elements 128 and / or mirrors 130 for imaging the photomask 120 onto the wafer 124. In this case, the individual lens elements 128 and / or mirrors 130 of the projection system 104 can be arranged symmetrically with respect to the optical axis 126 of the projection system 104. It should be noted that the number of lens elements 128 and mirrors 130 of the DUV lithography apparatus 100B is not limited to the number shown. A greater or lesser number of lens elements 128 and / or mirrors 130 can also be provided. In addition, the mirrors 130 are generally curved on their front sides for beam shaping.

[0090] The air gap between the last lens element 128 and the wafer 124 can be replaced by a liquid medium 132 with a refractive index > 1. The liquid medium 132 can be, for example, high-purity water. This arrangement is also referred to as immersion lithography and has improved lithography resolution. The medium 132 can also be referred to as an immersion liquid.

[0091] Figure 2A The optical device 200 according to a first exemplary embodiment is schematically shown in a plan view. Figure 2B The II-II cross-section taken from Figure 2A is shown. The device 200 can be used, for example, in one of the lithographic apparatuses 100A, 100B.

[0092] The optical device 200 includes one or more microsystems 202, only one of which is shown in the exemplary embodiment. The microsystem 202 includes a mirror array 204 having a plurality of mirrors 206. The mirrors 206 are shown by dashed lines in Figure 2A so as to allow viewing of the structure below the respective mirror 206.

[0093] The mirrors 206 are arranged in an array, that is, arranged in a plane, which can be flat or curved (even multiply curved). The mirrors 206 can be arranged in rows and columns, in particular in such a way that they occupy a square area. For example, 32×32 or 64×64 mirrors 206 can be provided for each microsystem 200. The microsystem 202 formed in this way can also be referred to as a “block”. The mirror surface 208 (hereinafter also referred to as the “front side”) of the respective mirror 216 can be, for example, less than or equal to 5 mm 2 、1 mm 2 or 0.5 mm 2 . During the exposure process of the lithographic apparatuses 100A, 100B, on the front side 208 or on the surface of the front side 208, the respective mirror 206 reflects a part of the working light 108A, 108B. Hundreds of microsystems 202 can be combined to form a unit, such as the faceted mirror 118 within the illumination system 102 (see Figure 1A ).

[0094] Furthermore, the microsystem 202 includes a two-dimensional monolithic substrate 210. “Monolithic” means that it is produced as a single piece or single crystal component. According to the first exemplary embodiment, the substrate 210 is made of a semiconductor material, such as silicon.

[0095] The mirror array 204 is arranged on the substrate 210. In this case, the respective mirror 206 is tiltably mounted on the substrate 210 by means of a mounting 212. For example, the mounting 212 can have one or more bends. Preferably, tilting can be performed about two mutually perpendicular axes x, y. The plane defined by the axes x, y is preferably oriented parallel to the main extension plane of the substrate 210 (corresponding to the Figure 2A plane of the paper in Figure 2BThe mirror 206 shown on the left is shown in a position tilted by an inclination angle α about the x-axis. Changing the inclination angle α has the effect of guiding the incident working light 108A, 108B, and thus appropriately affects the exposure.

[0096] One or more actuators 214 are provided for tilting the respective mirror 206 about the axes x, y. The respective actuator 214 can be composed of two electric combs 216, 218, where one electric comb 216 is arranged on the substrate 210 and the other electric comb 218 is arranged on the rear side 220 of the mirror 206, in particular on the surface 219 of the rear side 220 of the mirror 206. The electric combs 216, 218 engage with each other. The engagement depth is determined by the charge of the electric combs 216, 218. The relationship between the geometric arrangement of the actuator 214 on the rear side 220 of the mirror 206 and the respective engagement depth results in an inclination angle α about the x-axis and an inclination angle (not shown) about the y-axis. The actuator 214 is thus formed capacitively. However, other types of actuation, such as actuation by means of a Lorentz actuator, are also conceivable.

[0097] The substrate 210 has a plurality of radiation sources 222, precisely, preferably one radiation source 222 for each mirror 206. The radiation source 222 is formed as an LED, for example. Each radiation source 222 generates a measurement beam 224. The measurement beam 224 can include light in the visible spectrum or the near-infrared spectrum.

[0098] Downstream of the radiation source 222, an optical unit 226, such as a lens element, can be provided, which modifies the measurement beam 224. In this case, the modified measurement beam 224 impinges on a part 228 of the mount 212 and is reflected by it. This part 228 is firmly connected to the surface 219 of the rear side 220 of the mirror 206 and thus tilts completely with it. The reflected measurement beam is denoted by 224’. The reflection of the measurement beam 224 on this part 228 of the mount 212 has the effect of an indirect reflection of the measurement beam 224 on the rear side 220 of the mirror 206.

[0099] A plurality of sensor units 230 are arranged around the respective radiation source 222. The sensor unit 230 can be formed as a photodiode. Based on the sensor unit 230 irradiated by the measurement beam 224’, its deflection can be deduced, and thus the inclination angle α of the mirror 206 can be deduced. If the measurement beam 224’ has a limited range, such as a Gaussian profile, the inclination angle of the mirror 206 can be determined based on the ratio of the components of the measurement beam 224’ entering the sensor unit 230, as described above (centroid).

[0100] For example, four sensor units 230 can be provided, which are arranged in the quadrants around the radiation source 222. If an imaging CCD or CMOS chip with multiple (e.g., hundreds or thousands) of sensor units 230 is used, more precise sensing of the deflection of the measurement beam 224' and thus the tilt angle α can be achieved.

[0101] The determination of the tilt angle α can be carried out with the help of the microprocessor 232. The microprocessor 232 can be assigned storage means (not shown), such as read-only memory ROM, random access memory RAM, electrically erasable programmable read-only memory EEPROM, or flash memory. The microprocessor 232 controls the mirror 206 based on the setpoint tilt angle and the actual tilt angle. The microprocessor receives the setpoint tilt angle from the central control unit of the lithographic apparatuses 100A, 100B. The microprocessor 232 is connected to the sensor unit 230 for signal transmission purposes. The microprocessor 232 calculates the actual tilt angle from the sensor signals provided by the sensor unit, which are generated by the sensor unit based on the centroid of the reflected measurement beam 224'.

[0102] As shown, the microprocessor 232 together with the storage means can also be arranged on the substrate 210.

[0103] Preferably, all components of the microsystem 202 (except the substrate 210 itself), that is, the mirror 206, the mount 212, the actuator 214, the radiation source 222, the sensor unit 230, and / or the microprocessor 232 and the storage means, are produced by microsystem technology. This includes the use of semiconductor production methods, such as etching and spark erosion, and the use of thin-film technology (e.g., sputtering). In different cases, the size (maximum edge length) of the individual components is between 0.001 mm and 5 mm or less.

[0104] Furthermore, in the case of this first exemplary embodiment, the semiconductor material of the substrate 210 serves as the carrier material for the integrated circuit 234, which includes the radiation source 222, the sensor unit 230, and possibly the electrical comb 216 of the actuator 214 and / or the microprocessor 232 and the storage means as integrated component parts.

[0105] In different cases, unless otherwise indicated, the following exemplary embodiments are each based on the previous embodiment. Figure 3A The optical device 200 according to the second exemplary embodiment is schematically shown in a plan view. Figure 3B The III-III section from Figure 3A is shown.

[0106] Figure 3AShown is a first substrate 300, which comprises a semiconductor material, such as indium phosphide. This serves as a carrier material for an integrated optical unit 302. The integrated optical unit 302 includes an optical waveguide 304, a light output region 306, and a light input region 307. The (integrated) optical waveguide 304 is connected in a light guiding manner to a radiation source 310 outside the microsystem 202 via a port 309. For this purpose, an optical fiber cable 312 or the like connected to the port 309 is provided. The radiation source 310 generates light in the visible or near-infrared range.

[0107] In an alternative embodiment (not shown), the integrated optical unit 302 has a plurality of optical waveguides 304. These optical waveguides 304 respectively connect some of the light output regions 306 to respective ports 309.

[0108] The light output regions 306 are respectively connected in a light guiding manner to the optical waveguides 304, and the optical waveguides 304 provide light L in these regions. Downstream of each light output region 306, there may be, for example, a lens element 314, which provides a measurement beam 224 and guides it onto a portion 228 of the mount 212. Depending on the tilt angle α, the measurement beam 224' reflected at this portion 228 falls onto one of the light input regions 307. According to an exemplary embodiment, four light input regions 307 are provided, which are arranged in quadrants around the light output region 306 or its lens element 314. If a larger number of light input regions 307 are used, such as hundreds or thousands, a more precise sensing of the deflection of the measurement beam 224, and thus a more precise sensing of the tilt angle α, can be achieved.

[0109] In this case, a second substrate 210 is provided below the first substrate 300. Here, contrary to the first exemplary embodiment, the integrated circuit 210 does not have a radiation source 222. The sensor unit 230 is connected in a light guiding manner to the light input region 307 of the first substrate 300. In addition, the microprocessor 232 is connected, in terms of signal transmission, via an electrical vertical interconnection path 316 (also referred to as a via), through the first substrate 210, to the actuator 214 or an amplifier (not shown) upstream thereof. Depending on the amount of light reaching the sensor unit 230, the microprocessor 232 determines the tilt angle α of the corresponding mirror 206 (Gaussian intensity distribution and centroid determination, as described above). In the same manner as in the case of the exemplary embodiment according to Figure 2A and 2B the control of the tilt angle α thus takes place in the microsystem 202.

[0110] In an embodiment (not shown), a single substrate having both the integrated optical unit 302 and the integrated circuit 234 may be provided.

[0111] In the case of the second exemplary embodiment, one radiation source 310 per microsystem 202 suffices. Alternatively, one radiation source 310 can be provided that supplies light to a plurality of microsystems 202. This is the case as Figure 4 shown.

[0112] Figure 4 The optical device 200 according to the third exemplary embodiment is shown in a plan view, for example as seen in detail in one of the lithographic apparatuses 100A, 100B.

[0113] This includes, for example, a faceted mirror 118 (see also Figure 1A ), which has a plurality of mirror modules 400 (only one is shown for overall clarity), for example several hundreds. Each mirror module 400 in turn has a plurality of microsystems 202 as described in connection with Figure 3A and 3B . For example, a corresponding mirror module 400 can have from 2 to 1000 microsystems 202.

[0114] Each mirror module 400 or all mirror modules 400 are supplied with light L by a single radiation source 310. In the exemplary embodiment as Figure 4 shown, the radiation source 310 can be arranged not only outside the faceted mirror 118, but also outside the vacuum region 402 surrounding it. The housing separating the vacuum region 402 from the rest of the lithographic apparatus 100A is denoted by 404.

[0115] The light L generated by the radiation source 310 is transferred from the outside of the vacuum region 402 to the inside of the vacuum region 402 by means of a (VFT - vacuum feedthrough) interface 406. Via an optical waveguide 408, the light L is distributed among the microsystems 202. A channel 410 (for example in the form of an optical fiber cable) can be provided precisely, which optically connects the interface 406 to the faceted mirror 118 or to all or some of the microsystems 202 of the mirror module 400 or of the corresponding mirror module 400.

[0116] Likewise, in the case of the exemplary embodiment according to Figure 4 , the tilt angle control can be carried out successively within each microsystem 202 for the mirror 206 respectively included by that system, more precisely, in particular by means of the corresponding microprocessor 232.

[0117] Figure 5A The optical device 200 according to the fourth exemplary embodiment (in particular for one of the lithographic apparatuses 100A, 100B) is schematically shown in a plan view. Figure 5B A V - V cross - section from Figure 5A is shown.

[0118] The radiation source 310 generates light L with a time-varying wavelength (also referred to as "chirp") and thus generates the measurement beam 224. Figure 6 This light L is shown in an exemplary manner. Here, t represents time and λ represents the wavelength of the light. The variation of the wavelength λ over time corresponds to a sawtooth signal here. However, any other desired signal form is conceivable.

[0119] Another optical filter 308 is provided upstream of each light incidence region 307. Correspondingly, four filters 308-1 to 308-4, 308-5 to 308n (where "n" is the total number of filters 308 of each microsystem 202), etc. are provided for each light exit region 306 or lens elements 314-1, 314-2, 314-m (where "m" is the total number of light exit regions 306 or lens elements 314 of each microsystem 202) or mirrors 206-1, 206-k (where "k" is the total number of mirrors 206 of each microsystem 202), etc., and their wavelength passbands are different in different cases. The wavelength passbands are as Figure 6 shown, denoted by W 308-1 to W 308-n respectively.

[0120] The actual wavelength λ of the light L at the corresponding time point t act is known. For this purpose, the radiation source 310 can have the Figure 7 structure shown. The light L generated by the tunable laser 700 is separated. A part of the light L is provided to one or more microsystems 202. Another part of the light L passes through the Mach-Zehnder interferometer 702 and then irradiates on the photodiode 704, which is in turn connected to the evaluation electronics 706. Another part of the light L irradiates on the filter 708, and the filter 708 only allows the light with a predetermined wavelength λ 0 to pass through. The allowed light irradiates on the photodiode 710, which is in turn connected to the evaluation electronics 706.

[0121] The evaluation electronics 706 integrates the variation of the wavelength λ of the light L measured by means of the photodiode 704 over time. Using the λ 0 at a specific time point as a reference, this evaluation electronics can output the actual wavelength λ act at each time point t. The actual wavelength λ act is provided to the microprocessor 232 of the corresponding microsystem 202 (see Figure 5B ).

[0122] If the microprocessor 232 subsequently receives, within the time period t1 to t2 (see Figure 6 ), a signal from the sensor unit 230 (see Figure 5BIf the (electrical) signal of act is known, the microprocessor 232 can easily deduce that the sensor unit 230 (not shown as it is hidden) assigned to the filter 308-1 is the sensor unit on which the currently reflected measurement beam 224’ has impinged. Similarly, the signal in the time period t3 to t4 ( Figure 6 ) means that the measurement beam 224’ has impinged on the sensor unit 230-2 assigned to the filter 308-2. Additionally, if the actual intensity (centroid) of the reflected measurement beam 224’ is sensed and evaluated, the actual tilt angle α can be determined in different situations. This type of circuit allows for high-speed tilt angle control.

[0123] Based on the available bandwidth of the light L and the wavelength passbands W 308-1 to W 308-n of the filters 308-1 to 308-n, it can be stipulated that the cumulative wavelength passbands W 308-1 to W 308-4 , W 308-5 to W 308-8 etc. of the respective mirrors 206-1, 206k cover the entire available bandwidth of the light L. For example, this may be the case if each mirror 206 has a large number of sensor units 307 and the assigned filters available, or if the wavelength passbands are very wide. In this case, the microprocessor 232 requires additional information that allows the signals received from the sensor units 230 to be assigned to the respective mirrors 206. For example, this can be achieved by transmitting the signals of the respective mirrors 206 to the microprocessor 232 on different channels (one channel per mirror 206).

[0124] According to another variant, it can be stipulated that the cumulative wavelength passbands W 308-1 to W 308-n on the microsystem 202 cover the entire available bandwidth of the light L (as Figure 6 shown). In this case, the microprocessor 232 does not require the above-mentioned additional information.

[0125] Finally, it can be envisaged that only the cumulative wavelength passbands W Figure 4 or Figure 8 on the module 400 or the faceted mirror 118 (see 308-1 to W 308-m where M is the total number of different wavelength passbands in the respective module 400 or faceted mirror 118) cover the entire available bandwidth of the light L.

[0126] Figure 8 The device 200 according to the fifth exemplary embodiment is shown in a plan view and is, for example, clearly visible in one of the lithographic apparatuses 100A, 100B.

[0127] In the case of an exemplary embodiment according to Figure 8 , the radiation source 310 shown in Figure 7 is used. This provides light L to the microsystem 202 in a plurality of modules 400 of the faceted mirror 118 via the interface 406, as described in connection with Figure 4 . However, contrary to the exemplary embodiment according to Figure 4 , the wavelength of the light L varies over time t.

[0128] For such a system, the microsystem 202 has the following structure as described in Figure 9A and 9B . Figure 9A A plan view is schematically shown. Figure 9B Shows Figure 9A the IX - IX cross section of

[0129] The microsystem 202 has a substrate 300 as described in Figure 5A and 5B , and an integrated optical unit 302. The microsystem 202 preferably does not have a substrate 210 with an integrated circuit 234.

[0130] In addition to the components described with respect to Figure 5A and 5B , the integrated optical unit 302 includes an optical waveguide 900 that guides the light L' of the reflected measurement beam 224' from the light incident region 307 to the port 902 on the substrate 300. At the port 902, the light L' is transmitted to an optical fiber cable (not shown) or the like, and as shown in Figure 8 , is passed on to the interface 800 at the housing 404. A plurality of optical waveguides 900 can also be provided, each guiding the light L' from some of the light incident regions 307 to corresponding ports 902 (not shown). The light incident region 307 together with the filters 308 - 1 to 308 - n is designed in the same way as in the case of the exemplary embodiment according to Figure 5A and 5B .

[0131] As shown in Figure 8 , the light L' from the modules 400 including a plurality of microsystems 202 is guided to the interface 800 through exactly one channel 802 (for example, in the form of an optical fiber cable). As an alternative, it can be provided that the light L' of the microsystems 202 of some modules 400 or even the light L' of the microsystems 202 of all modules 400, that is, the faceted mirror 118 as a whole, is guided to the interface 800 through exactly one channel 802.

[0132] Downstream of the interface 800 is the sensor unit 804, on which the light L’ impinges. The electrical signal generated by the sensor unit 804 is amplified in the amplifier 806 and supplied to the control and evaluation unit 810 via the analog-to-digital converter 808. The control and evaluation unit 810 is formed as a microprocessor, in particular a programmable logic or an ASIC (application-specific integrated circuit), and can have suitable storage means, such as a read-only memory ROM, a random access memory RAM, etc.

[0133] For the purpose of signal transmission, the control and evaluation unit 810 is also connected to the radiation source 310. Thereby, the control and evaluation unit 810 receives the actual wavelength λ of the light L emitted at the respective time point t. act Thus, the control and evaluation unit 810 can derive the actual tilt angle α of the respective mirror 206 from the detection of the signal intensity of the sensor unit 804 over a certain period of time by means of a corresponding centroid calculation (see above). act The sensor unit 804, for example, includes four wavelength passbands W 308-1 to W 308-n . Thus, information about the actual tilt angle α of the respective mirror 206 on the channel 802 act is advantageously transmitted to the control and evaluation unit 810 during the multiplexing process (in particular based on the time-dependent wavelength of the light L and the filters 308-1 to 308-n). With the information about the actual wavelength λ act from the radiation source 310, the information about the actual tilt angle α act is demultiplexed again by the control and evaluation unit 810 and assigned to the respective mirror 206.

[0134] It can also be provided that the control and evaluation unit 810 controls the tunable radiation source 310 for generating light L of a setpoint wavelength λ set . Finally, the control and evaluation unit 810 can be set to activate the actuator 214 for setting the setpoint tilt angle α set of the respective mirror 206. The setpoint tilt angle α set can also be provided for the respective actuator 214 via a waveguide (not shown).

[0135] The components 804, 806, 808, and 810 are all arranged outside the vacuum region 402. The functions provided by the components 804, 806, 808, and 810 can also be provided by different circuits; what is shown here is given purely by way of example. For example, the parts of the evaluation unit 810 can be implemented not in digital form but in analog form.

[0136] Figure 10AA microsystem 202 (in particular for one of the lithographic apparatuses 100A, 100B) according to a fifth exemplary embodiment is schematically shown in a plan view. FIG. 10 shows a cross-section X-X from Figure 10A thereof.

[0137] This structure corresponds to Figure 5A and 5B the structure, and the substrate 1000 corresponds to Figure 5A and 5B the substrate 300, but differs in that light-emitting and light-incident regions 1002 (e.g., in the form of grating couplers) are provided. These regions are respectively provided below the peripheral regions 1004 of the mirrors 206 in the substrate 1000 and are part of the integrated optical unit 302. The corresponding light-emitting and light-incident regions 1002 use the light L provided by the optical waveguide 304 to provide a measurement beam 224, and the measurement beam 224 is reflected back to the light-emitting and light-incident regions 1002 in the peripheral region 1004. The reflected measurement beam 224’ is shown in Figure 10B as being almost identical to the measurement beam 224. The peripheral region 1004 forms part of the surface 219 of the rear side 220 of the mirror 206. The reflection of the measurement beam 224 at the peripheral region 1004, that is, at the surface 219, has the effect of the measurement beam 224 being directly reflected on the rear side 220 of the mirror 206. The peripheral region 1004 or the surface 219 may have a rough form in order to scatter the measurement beam 224 to some extent. This allows for better sensing of the reflected measurement beam 224’ at the light-emitting and light-incident regions 1002.

[0138] The reflected measurement beam 224’ is coupled back into the optical waveguide 304 or another optical waveguide 900 through the light-emitting and light-incident regions 1002 (the light returning in the optical waveguide is denoted by L’), and optically overlaps with the light L in the sensor unit 1200 (see Figure 12 ). Output light L is provided at the sensor unit 1200 from the radiation source 310 through the connector 1202 (see Figure 12 ). By applying the FMCW-LIDAR method, the distance A 1 、A 2 between the corresponding light-emitting and light-incident regions 1002 and the corresponding peripheral regions 1004 can be determined from the interference signal. In the aforementioned case where the reflected light L’ propagates back in the same optical waveguide 304, a circulator (not shown) is provided to couple the light L’ out of the optical waveguide 304 and into the sensor unit 1200.

[0139] This FMCW-LIDAR method is as Figure 11As shown. The light L of the measurement beam 224 has a wavelength λ and a corresponding frequency that varies with time t. Due to the signal transmission time for reaching the corresponding peripheral region 1004 and returning, the reflected measurement beam 224' (i.e., the echo) has a wavelength or frequency at the light exit and light incidence region 1002 that is different from that of the measurement beam 224 leaving the light exit and light incidence region 1002 at the same time point t 1 The wavelength difference Δλ or frequency difference is determined by means of the above-mentioned interference signal. The wavelength difference Δλ or frequency difference is used to calculate the signal transmission time and thus the distance A 1 、A 2 。In a variant of the FMCW-LIDAR method, additionally or alternatively, the phase difference between the transmitted and reflected measurement beams 224, 224' is measured and used to determine the distance A 1 、A 2 。

[0140] If three or more light exit and light incidence regions 1002 (four in this example) are provided for each mirror 206, the tilt angle α can be accurately determined.

[0141] In addition to the different ways of sensing the tilt angle α of the corresponding mirror 206 described above, the above exemplary embodiments are correspondingly applicable to the exemplary embodiments according to Figure 10A and 10B 。

[0142] Particularly advantageously, the exemplary embodiments according to Figure 10A and 10B can be combined with those exemplary embodiments that provide a tunable radiation source 310, because they already provide the light L with a time-dependent wavelength or frequency required by the FMCW-LIDAR method. This is shown by way of example in Figure 12 。This shows a modified illustration of Figure 8 。A sensor unit 1200 for sensing multiplexed signals from the light exit and light incidence regions 1002 is provided here.

[0143] Although the present invention has been described based on exemplary embodiments, the present invention can be modified in various ways.

[0144] List of reference symbols

[0145] 100A EUV lithography apparatus

[0146] 100B DUV lithography apparatus

[0147] 102 Beam shaping and illumination system

[0148] 104 Projection system

[0149] 106A EUV Radiation Source

[0150] 106B DUV Radiation Source

[0151] 108A EUV Radiation

[0152] 108B DUV Radiation

[0153] 110 Mirror

[0154] 112 Mirror

[0155] 114 Mirror

[0156] 116 Mirror

[0157] 118 Mirror / Faceted Mirror

[0158] 120 Photomask

[0159] 122 Mirror

[0160] 124 Wafer

[0161] 126 Optical Axis

[0162] 128 Lens Element

[0163] 130 Mirror

[0164] 132 Medium

[0165] 200 Device

[0166] 202 Microsystem

[0167] 204 Mirror Array

[0168] 206 Mirror

[0169] 208 Front Side

[0170] 210 Substrate

[0171] 212 Mounting

[0172] 214 Actuator

[0173] 216 Electric Comb

[0174] 218 Electric Comb

[0175] 219 Surface

[0176] 220 Rear Side

[0177] 222 Radiation Source

[0178] 224 Measuring Radiation

[0179] Measured light beam reflected by 224'

[0180] 226 Optical unit

[0181] 228 Portion

[0182] 230 Sensor unit

[0183] 232 Microprocessor

[0184] 234 Circuit

[0185] 300 Substrate

[0186] 302 Optical unit

[0187] 304 Light guide

[0188] 306 Light exit area

[0189] 307 Light incident area

[0190] 308 Filter

[0191] 309 Port

[0192] 310 Radiation source

[0193] 312 Fiber optic cable

[0194] 314 Lens element

[0195] 316 Vertical interconnection path

[0196] 400 Mirror module

[0197] 402 Vacuum area

[0198] 404 Housing

[0199] 406 Interface

[0200] 408 Light guide

[0201] 410 Channel

[0202] 700 Laser

[0203] 704 Photodiode

[0204] 706 Evaluation electronics

[0205] 708 Optical filter

[0206] 710 Photodiode

[0207] 800 Interface

[0208] 802 Channel

[0209] 804 Sensor unit

[0210] 806 Amplifier

[0211] 808 Analog-to-digital converter

[0212] 810 Control and evaluation unit

[0213] 900 Optical waveguide

[0214] 902 Port

[0215] 1000 Substrate

[0216] 1002 Light emission and light incidence area

[0217] 1004 Peripheral area

[0218] 1200 Sensor unit

[0219] 1202 Connector

[0220] A Distance

[0221] L Light

[0222] L’ Light

[0223] M1 Mirror

[0224] M2 Mirror

[0225] M3 Mirror

[0226] M4 Mirror

[0227] M5 Mirror

[0228] M6 Mirror

[0229] W Wavelength passband

[0230] t Time

[0231] x-axis

[0232] y-axis

[0233] α Tilt angle

[0234] λ Wavelength

Claims

1. An optical device (200) for a lithographic apparatus (100A, 100B), comprising: A microsystem (202) having a mirror array (204), wherein respective mirrors (206) of the mirror array (204) are arranged to reflect the working light (108A, 108B) of the lithographic apparatus (100A, 100B) at their front sides (208) and also to reflect a measurement beam (L, 224) at their rear sides (220), One or more radiation sources (222, 310), arranged outside the microsystem (202) and outside the vacuum region of the optical device (200), and configured to provide respective said measurement beams (L, 224), and One or more sensor units (230, 804, 1200), configured to sense the tilt angle (α) of respective mirrors (206) based on the respective reflected measurement beams (L’, 224’), Wherein, The microsystem (202) has a substrate (210, 300, 1000) and an integrated circuit (234).

2. The optical device according to claim 1, Wherein, The mirror array (204) is arranged on the substrate (210, 300, 1000), and wherein respective mirrors (206) are tiltably mounted on the substrate (210, 300, 1000).

3. The optical device according to claim 1 or 2, Wherein, The microsystem (202) has an integrated optical unit (302), the integrated optical unit (302) being configured to direct the provided measurement beam (L, 224) to respective mirrors (206).

4. The optical device according to claim 3, Wherein, The integrated optical unit (302) is configured to direct the respective reflected measurement beam (L’, 224’) or a signal generated based on the respective reflected measurement beam (L’, 224’) to the one or more sensor units (230, 804, 1200).

5. The optical device according to claim 1 or 2, Wherein, The integrated circuit includes one or more sensor units (230).

6. The optical device according to claim 1 or 2, Characterized in that, The one or more sensor units (804, 1200) are arranged outside the microsystem (202).

7. The optical device according to claim 1 or 2, Wherein, The radiation source (310) is arranged to provide the measurement beam (L, 224) at a wavelength (λ) that varies over time (t), where a respective mirror (206) is assigned one or more filters (308-1 to 308-n), the one or more filters (308-1 to 308-n) being arranged to allow the reflected measurement beam (L', 224') or a signal generated by the reflected measurement beam (L', 224') to pass and be transmitted to the one or more sensor units (230, 804, 1200) only within a predetermined wavelength passband (W 308-1 to W 308-n ), where the wavelength passbands (W 308-1 to W 308-n ) of the filters (308-1 to 308-n) are different from each other.

8. The optical device according to claim 1 or 2, Wherein, The microsystem (202) has multiplexers (308-1 to 308-n, 310) configured to multiplex the reflected measurement beam (L’, 224’) or a signal generated by the reflected measurement beam (L’, 224’) onto an optical waveguide (802), and wherein the microsystem (202) further has demultiplexers (804, 810) configured to demultiplex the measurement beam (L’, 224’) or signal multiplexed onto the optical waveguide (802).

9. The optical device according to claim 1 or 2, wherein, the one or more sensor units (230, 804) are configured to sense the tilt angle (α) of the respective mirror (206) based on the deflection of the reflected measurement beam (L’, 224’) relative to the provided measurement beam (L, 224).

10. The optical device according to claim 9, wherein, the microsystem (202) has a first substrate (300) with a plurality of light incident regions (307) and a second substrate (210) with a plurality of sensor units (230), wherein the plurality of light incident regions (307) are configured to direct the reflected measurement beam (L’, 224’) to the plurality of sensor units (230).

11. The optical device according to claim 10, wherein, The plurality of light incident regions (307) include filters (308-1 to 308-n) having different wavelength passbands (W 308-1 to W 308-n ).

12. The optical device according to claim 1 or 2, wherein, the one or more sensor units (1200) are configured to sense the tilt angle (α) of the respective mirror (206) by means of a distance measurement that depends on the provided and reflected measurement beams (L, 224; L', 224').

13. The optical device according to claim 12, wherein, the one or more sensor units (1200) are configured to perform the distance measurement according to the FMCW-LIDAR method.

14. A lithographic apparatus (100A, 100B) comprising an optical device (200) according to any one of claims 1 to 13.

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