MEMS with an optical component and several stacked integrated circuits

Abstract

Microelectromechanical system (MEMS) for a device with one or more optical components (20) with 1.1. a suspension for an optical component (20), 1.2. one or more actuator elements (62) for relocating the optical component (20) and / or one or more sensor elements (61) for detecting a relocation of the optical component (20) and 1.3. a large number of integrated circuits (ICs) (64, 65, 68), 1.4. wherein the integrated circuits (64, 65, 68) are arranged in a stacked configuration and 1.5. wherein the integrated circuits (64, 65, 68) 1.5.1. at least two different types from the following list: actuator electronics, sensor electronics and control electronics and / or 1.5.2. comprising at least two different types of silicon vias (TSVs), characterized in that it comprises different types of electrical connections between different ICs (64, 65, 68), wherein the types of electrical connections are selected from the list of silicon vias (63), wire bonds (72) and wire and bump connections (66).

Description

[0001] The invention relates to a microelectromechanical system (MEMS), in particular a MEMS for a device having one or more optical components, in particular in the form of a micromirror. The invention further relates to a micromirror and an optical component comprising an array of a plurality of micromirrors. Furthermore, the invention relates to an illumination optics system and an illumination system for a lithography system, a projection optics system for a lithography system, and a lithography system. Finally, the invention relates to a method for producing an optical component.

[0002] The ever-increasing demands of the semiconductor market require the further development and continuous improvement of lithography systems, especially the illumination optics for these systems. Such illumination optics can consist of a facet module with several hundred densely stacked mirror elements, each of which can be tilted along two tilt axes.

[0003] Such modules with a large number of individually controllable micromirrors are known from WO 2012 / 130 768 A2 and WO 2015 / 028 450 A1.

[0004] An electronic unit comprising a first substrate, a second substrate and at least one spacer substrate arranged between the first and the second substrate is known from US 10,515,886 B2.

[0005] US 2022 / 0 004 107 A1 relates to an optical arrangement and lithography system.

[0006] DE 10 2011 006 100 A1 concerns a mirror array.

[0007] DE 10 2020 120 906 A1 relates to a method for determining a torsion angle of a mirror body of a MEMS device.

[0008] US 2019 / 0 018 114 A1 concerns a chip-scale lidar with a single mems scanner in a compact optical package.

[0009] It is the object of the present invention to improve a microelectromechanical system (MEMS) for a device comprising one or more optical components, in particular one or more micromirrors, in particular one or more circular gimbal mirrors.

[0010] This problem is solved by the subject matter of claim 1.

[0011] According to one aspect of the invention, the micro-electromechanical system (MEMS) comprises a plurality of integrated circuits (ICs) of different types and / or with different types of silicon vias (TSVs), wherein the ICs are arranged in a stacked manner.

[0012] The ICs may in particular comprise actuator electronics and / or sensor electronics and / or control electronics.

[0013] The actuator electronics can in particular consist of or contain amplifiers and / or drivers.

[0014] The actuator electronics can in particular comprise or consist of high-voltage electronics (HV), in particular for voltages of at least 50 V, in particular at least 100 V, in particular at least 140 V, in particular at least 180 V, in particular at least 200 V.

[0015] The actuator electronics can in particular include or consist of high-voltage ASICs.

[0016] The sensor electronics may in particular comprise or consist of analog front-end electronics.

[0017] The sensor electronics may in particular comprise or consist of low-voltage electronics (LV), in particular for voltages of no more than 50 V, in particular no more than 36 V.

[0018] The sensor electronics may in particular include or consist of low voltage (NV) ASICs.

[0019] For example, the controller can provide a closed-loop control, a feedback or feedforward function, can store calibration data and recalculate the control based on this data and several acquired external or internal parameters.

[0020] The ICs may also be referred to as chips, dies or wafers, specifically as chips with ICs, dies with ICs or wafers with ICs.

[0021] The invention will be described below with reference to a displaceable micromirror. This is not to be understood as limiting. The micromirror serves primarily as an explicit example of an optical component. Instead of a micromirror, the invention can advantageously be used with any other displaceable optical component.

[0022] The MEMS can be used particularly advantageously with a circular gimbal mirror (CCM).

[0023] By arranging multiple integrated circuits in a stacked fashion, the available space for electronic circuitry within a given footprint of a micromirror is increased. This allows for the generation of a larger drive voltage for an actuator to move a micromirror and / or an improvement in the electronics for detecting the displacement of a micromirror and / or an improvement in the electronics of a control logic device.

[0024] In addition, heat dissipation from a micromirror can be improved.

[0025] Advantageously, the electronic circuits of the control devices and / or the sensor devices and / or the control logic devices for a single micro-minus mirror are arranged within the footprint of such a micro-mirror. This allows the need for individual positioning of each mirror to be met and the dense coverage of the mirror array to be improved.

[0026] In particular, a stacked arrangement of integrated circuits can achieve a higher drive voltage or a stronger force / torque for displacing a micro-mirror. The integrated circuits can be arranged three-dimensionally or vertically stacked. In particular, they can be arranged in multiple layers behind the micro-mirror. The individual layers can be arranged obliquely, in particular perpendicularly, to a surface normal of the micro-mirror. The dies can, in particular, be arranged so that their surface runs parallel to that of the mirror.

[0027] According to the invention, a strong force for tilting a mirror can be generated even though the space below the mirror is very limited.

[0028] In particular, high drive voltages of over 100 V, in particular over 140 V, in particular over 180 V can be generated to move a mirror, although the space below the mirror in which the electronic components for generating and / or amplifying the drive voltage are to be arranged, in particular its cross-sectional area, is very limited.

[0029] In particular, the stacked arrangement of the ICs makes it possible to generate and / or control the necessary driver voltages at the mirror base surface.

[0030] In addition, the sensor signals can be amplified and read as close as possible to the transducer for converting the movement into an electrical signal.

[0031] In addition, a control loop can be provided between the sensors and the actuators to keep the alignment of the mirror stable.

[0032] It was recognized that higher drive voltages or more force and thus the successful realization of 2D tilting mirrors for applications with high thermal load, such as EUV systems, can be achieved by extended 3D or vertical stacking of the front-end (FE) driver and / or FE sensor electronics and / or the back-end (BE) control loop electronics.

[0033] A stacked arrangement can, in particular, mean that at least two integrated circuits are arranged in different planes, in particular in parallel planes. This does not preclude the possibility of multiple integrated circuits being arranged in a common plane.

[0034] The microelectromechanical system may comprise at least two, in particular at least three, in particular at least four, in particular at least six, in particular at least 12 separate integrated circuits.

[0035] The integrated circuits can be arranged in at least two, in particular at least three, in particular at least four, in particular at least six different layers or levels. A large number of levels allows for a larger number of separate integrated circuits.

[0036] The integrated circuits can be application-specific integrated circuits (ASICs).

[0037] The integrated circuits can consist of single-sided integrated circuits and / or double-sided integrated circuits. This refers to the arrangement of electronic circuits on the integrated circuits.

[0038] The available area for arranging the integrated circuits can be smaller than 1 cm × 1 cm, in particular smaller than 0.5 cm × 0.5 cm, in particular smaller than 0.3 cm × 0.3 cm, in particular smaller than 0.2 cm × 0.2 cm, in particular at most 1 mm2 , in particular not more than 0.65 mm 2 be.

[0039] The available floor space can be determined by the dimensions, in particular by a cross-sectional area, of a micromirror, in particular its substrate or its reflection surface.

[0040] The integrated circuits may all be at most as large as the available footprint. In particular, they may be at most half the size of the available footprint. The ratio between the available footprint and the size of an individual integrated circuit may be at least 3, in particular at least 4, in particular at least 6.

[0041] It is also possible for one or more ICs to extend over the available floor space, in particular over the available floor space defined by a micromirror. One or more ICs may in particular be larger than the available floor space, in particular larger than the cross-sectional area of ​​the micromirror, in particular its substrate, or larger than its reflective surface. This can be particularly useful for electronic circuits that control more than a single micromirror. For example, the ICs may also be up to twice the floor space, since one IC can control 2 mirrors or 2x1 mirrors, or up to four times the floor space, since one IC can control 4 mirrors, in particular 2x2 mirrors, or up to 6 mirrors, in particular 3x2 mirrors, or up to 9 mirrors, in particular 3x3 mirrors, or up to 16 mirrors, in particular 4x4 mirrors or more.

[0042] According to one aspect of the invention, the MEMS comprises a suspension for a micromirror. Preferably, the suspension is constructed from a material with high thermal conductivity λ, such as crystalline silicon, aluminum, gold, or copper. The thermal conductivity of the material from which the suspension is made can be at least 140 W / mK, in particular at least 200 W / mK, in particular at least 300 W / mK, and in particular at least 380 W / mK.

[0043] The suspension may comprise or consist of one or more springs, in particular torsion springs or bends.

[0044] The suspension can be designed as a flexural element or a joint, particularly a cardan joint. The mirrors are therefore also called gimbal mirrors.

[0045] According to one aspect of the invention, the electrical connections between different ICs and / or between an IC and a substrate for suspending one or more micromirrors comprise through-silicon vias (TSVs) and / or wire bonds and / or wire and bump connections. Different ICs can also be electrically connected by stacking bonded dies. Different ICs can also be electrically connected by stacked, electrically connected dies.

[0046] Silicon vias (TSVs) can be made from a material with high thermal conductivity, such as the suspension material mentioned above, e.g., Cu, Si / poly-Si, Al, Au. TSVs can be made from copper or poly-Si, in particular.

[0047] Copper TSVs are particularly good thermal and electrical conductors, while poly-Si TSVs conduct electrical signals well and heat moderately well. On the other hand, poly-Si TSVs enable subsequent high-temperature processes, for example, for the implantation and annealing of CMOS circuits. The ICs can be arranged as a three-dimensional stepped stack. The stacking direction can be perpendicular to the surface of the IC chips.

[0048] According to one aspect of the invention, the MEMS comprises one or more interposer chips. Such interposer chips may only have electrical and / or thermal connections, but no active electronic circuitry. An interposer chip may, in particular, be configured as a wafer with vertical interconnections. The vertical interconnections may be formed by TSVs.

[0049] In particular, the interposer chips may comprise TSVs of various types. For details, please refer to the above description.

[0050] In particular, it is possible for one or more interposer chips to comprise TSVs of different types. In particular, it is also possible for one or more interposer chips to comprise only TSVs of a single type.

[0051] In particular, electrical and / or thermal connections from and / or to the optical component can be partially or completely ensured by the TSVs. In particular, the TSVs can form a bridge between the actuator electronics and / or sensor electronics, the optical component, and an interface for connection to an external device and / or source. The electrical power supply and possible digital and / or analog input and / or output signals can be routed from / to a rear-mounted electrical connector through the controller chips, then through the FE chips, and then through the body / substrate of the optical component to the sensors and actuators and back. Thermal paths can lead from the optical element through its substrate, through the FE, through the control unit, to a rear-mounted heat sink.

[0052] The interposer chips can also contain integrated electronic circuits on one or both sides. It is also possible to use hybrid electronic chips that contain single-sided or double-sided electronic circuits and TSVs on a single die. The TSVs can, in particular, conduct electrical signals and / or heat.

[0053] The electronic components, especially the ICs, can be arranged in a cascade.

[0054] The electronic components, in particular the ICs, can be partially or completely electrically and / or thermally connected to a mirror element by interposer chips with vertical interconnects (TSVs) and / or via bonds and / or via and bump connections.

[0055] According to one aspect of the invention, one or more sensor readout ASICs and / or one or more actuator drivers and / or one or more control logic devices are included on different integrated circuits, wherein these different integrated circuits are arranged stacked one behind the other.

[0056] This allows the size of the individual ICs to be reduced.

[0057] According to one aspect of the invention, the ICs for the actuator electronics can provide drive signals of at least 100 V, in particular of at least 140 V, in particular of at least 170 V, in particular of at least 200 V.

[0058] Two drive signals can be provided for each degree of freedom. The optical component can be tilted around two independent tilt axes.

[0059] The ICs for the actuator electronics can each have a cross-sectional area of ​​no more than 4 mm 2 , in particular of a maximum of 2.5 mm2 , in particular of no more than 1 mm 2 , in particular of a maximum of 0.7 mm 2 have.

[0060] The ICs for the actuator electronics can in particular be amplifier circuits and / or driver circuits.

[0061] The ICs for the actuator electronics can be electrically connected to an external voltage generator.

[0062] One aspect of the invention is that the MEMS comprises a low-temperature single-fired ceramic (LTCC) substrate with integrated ICs. This technology enables robust assembly and packaging of electronic components. The ceramic components are manufactured using a multilayer process. The starting material is raw composite ribbons consisting of ceramic particles mixed with polymeric binders. The ribbons are flexible and can be processed, for example, by cutting, milling, punching, and embossing. Metal structures can be added to the layers, which is usually done by via filling and screen printing. Cavities are reinforced. The individual ribbons are then bonded together in a lamination process before the components are fired in a furnace, where the polymer portion of the ribbon burns and the ceramic particles sinter together, creating a hard and dense ceramic component.

[0063] The LTCC carrier can serve as a support and / or contribute to electrical and / or thermal conductivity.

[0064] The LTCC carrier can consist of different layers, especially layers with different types of ICs. For details on the different ICs, please refer to the corresponding description.

[0065] Different LTCC layers can be arranged horizontally shifted, in particular such that the ICs incorporated in adjacent layers overlap at most partially in a vertical projection. In particular, different LTCC layers can be arranged horizontally shifted so that the ICs incorporated in adjacent layers do not overlap in a vertical projection.

[0066] The ICs can be bonded or glued to the respective layers of the LTCC.

[0067] According to one aspect of the invention, the MEMS can comprise an actuator and / or a sensor with a comb structure, in particular with a radial comb structure. For details of such a comb structure, reference is made to DE 10 2015 204 874 A1, the content of which is hereby incorporated in its entirety into the present invention.

[0068] According to one aspect of the invention, the MEMS may comprise a heat sink. The heat sink is preferably in thermal communication with the micromirror.

[0069] The heat sink can be arranged on a side opposite a reflective surface of the micromirrors with respect to the electronic components. It can also be arranged between different electronic components, in particular between different ICs.

[0070] According to a further aspect, the chips, in particular the front-end electronics chip and / or the controller electronics chip, can be very thin. They can, in particular, have a thickness of at most 100 µm, in particular of at most 80 µm, in particular of at most 60 µm. They can, for example, have a thickness in the range from 50 µm to 100 µm. This can be achieved, in particular, by thinning them from the standard wafer thickness, e.g., 525 µm for a wafer with a 100 mm diameter down to 775 µm for a wafer with a 300 mm diameter. The thinning can be carried out by grinding and optionally subsequent polishing.

[0071] Thinned wafers are very flexible, similar to thin metal sheets, and therefore easily conform to the surfaces to which they are bonded. The substrates containing the front-end electronics and / or the controller electronics can be particularly flexible. They can be reversibly deformable.

[0072] According to a further aspect, adjacent substrates, which are arranged in particular between the micromirrors and the support structure, can be connected by full-surface mechanical / thermal connections; for obvious reasons, electrical connections are generally not full-surface. This means that the substrates are bonded to each other over a wide, flat, essentially uninterrupted area.

[0073] This can significantly improve heat transfer between adjacent substrates. One or more, in particular all, of the substrates between the mirrors and the support structure can comprise a selection of one or more of the following layers: - one or more connecting layers, which are arranged in particular on the front side of a substrate, - one or more redistribution layers, which are arranged in particular on the back of a substrate, - one or more electronic component layers, in particular with integrated circuits, - at least one bonding interface layer, in particular on its front side and / or on its back side.

[0074] The “front side” is the side on which the component layer is located.

[0075] The back side refers to the side on which the wafers are processed.

[0076] The large-area thermal connection between adjacent substrates significantly reduces the vertical thermal resistance. In the case of a solder bump connection, the thermal resistance across the bond layer can be between 49 mK / (Wcm 2 ) and 280 mK / (Wcm 2 ) are below the following assumed typical values: the bump height is between 50 µm and 1000 µm, the thermal conductivity of the solder is between 50 W / (m K) and 70 W / (m K), the thermal conductivity of the epoxy filler material is between 0.3 W / (m K) and 0.7 W / (m K) and the surface coverage of the solder bump is between 0.2 and 0.5. This reduces to practically zero, which in practice is several mK / (Wcm 2 ) means.

[0077] In addition, the thermal resistance can be kept very homogeneous over the lateral extent of the substrates, since a reduction of the variation of the absolute thermal resistance by the same order of magnitude is to be expected.

[0078] The thermal resistance can vary across the bonding layer by a maximum factor of 6, in particular by a maximum factor of 4, in particular by a maximum factor of 2.

[0079] A further object of the invention is to improve a micromirror and / or a micromirror array and / or an optical component with a micromirror array.

[0080] This object is achieved by a micromirror, a micromirror array and an optical component with a micromirror array with a MEMS according to the above description.

[0081] In particular, the MEMS can be arranged entirely within the footprint of a single mirror substrate.

[0082] The MEMS can also be connected to an array of e.g. 2 × 2, 2 × 3, 3 × 3, 4 × 4 or more mirrors.

[0083] The MEMS can have a maximum cross-sectional area of ​​1 cm 2 , especially 0.1 cm 2, in particular not more than 1 mm 2 have.

[0084] The integrated circuits can be front-end ASICs with a total size of less than 9 mm 2 , especially less than 5 mm 2 , especially less than 3 mm 2 , especially less than 1 mm 2 include.

[0085] The reflective surface of the mirror substrate may have an EUV reflective coating. The EUV reflective coating may be implemented as a Si-Mo multilayer structure.

[0086] The micromirror may have a tilt range of at least 50 mrad, in particular of at least 70 mrad, in particular of at least 100 mrad, in particular of at least 120 mrad. The tilt range may be at most 500 mrad.

[0087] The tilt accuracy of the micromirror can be better than 100 µrad, in particular better than 50 µrad, in particular better than 30 µrad and in particular better than 10 µrad.

[0088] The micromirror may comprise one or more actuators, in particular electrostatic actuators. The actuators may in particular comprise comb structures, in particular radial comb structures.

[0089] The micromirror can be suspended using a gimbal, particularly a universal joint. For details, see DE 10 2015 204 874 A1.

[0090] Micromirrors with a radial electrode structure and a cardan joint are also called circular gimbal mirrors (CCMs).

[0091] The actuators are preferably made of piezoceramic. The actuators are preferably designed as electrostatic combs. These can also be made of piezoceramic.

[0092] The micromirror can contain one or more sensors.

[0093] The sensors can detect the displacement, in particular the tilt, of the micromirror with an accuracy of better than 100 µrad, in particular better than 50 µrad, in particular better than 30 µrad, in particular even better than 10 µrad.

[0094] The sensors can be designed as electrostatic combs or as piezoresistive sensors.

[0095] The MEMS can advantageously include temperature measurement with an accuracy in the mK range.

[0096] Preferably, the mirrors are designed to be suitable for use in a low-pressure environment, in particular in a vacuum environment, in particular in an environment with a residual partial pressure of hydrogen of at most a few Pascals, in particular at most 3 Pa.

[0097] In particular, the micromirror can be designed to be suitable for an ionized environment, in particular an EUV environment.

[0098] The above properties apply to a single micromirror or, in the case of a mirror array, to each of the micromirrors of such an array.

[0099] An optical component comprising such an array of micromirrors can be used as a facet mirror of an illumination optics for a lithography system. It can be used, in particular, as a field facet mirror or as a pupil facet mirror of such an illumination optics. Such an optical component can also be used as a condenser mirror.

[0100] A further object of the invention is to improve an illumination optics for a lithography system and an illumination system for a lithography system or a projection optics for a lithography system and a lithography system with such an illumination optics and / or such a projection optics.

[0101] These tasks are solved by corresponding illumination optics, illumination systems, projection optics or lithography systems, which comprise one or more optical components according to the preceding description.

[0102] The illumination optics offer flexible illumination settings. In particular, they can provide a small pupil fill ratio.

[0103] The pupil filling ratio may be no more than 50%, in particular less than 25%, in particular less than 10%, in particular less than 5%.

[0104] The projection optics can, in particular, have an object-side numerical aperture of at least 0.3, in particular of at least 0.5. This allows a high resolution of the projection optics to be achieved.

[0105] Another object of the present invention is to improve a method for manufacturing a MEMS for an optical component.

[0106] This task is accomplished by a procedure that includes the following steps: Providing a variety of separate integrated circuits (ICs) or chips,

[0107] Arranging the integrated circuits in a stacked form, wherein at least two different integrated circuits are manufactured or processed using different technologies and / or wherein at least two different integrated circuits have TSVs of different types.

[0108] At least two different chips can be manufactured or processed in different temperature ranges.

[0109] In particular, it is possible to process at least one chip in a high-temperature process, in particular at a temperature of at least 400 °C, in particular at a temperature of at least 500 °C, in particular at a temperature of at least 700 °C, in particular at a temperature of at least 900 °C.

[0110] It is particularly possible to process at least one chip in a low-temperature process, in particular at a temperature of at most 400 °C, in particular at a temperature of at most 350 °C, in particular at a temperature of at most 300 °C, in particular at a temperature of at most 250 °C.

[0111] At least two different ICs can contain TSVs of different types, in particular with different functions and / or made of different materials.

[0112] The TSVs can in particular fulfill at least two of the following functions: - TSVs that only serve as thermally conductive structures, - TSVs, which serve as thermally conductive structures and for the transmission of NV (digital) signals, - TSVs, which serve as thermally conductive structures and for the transmission of HV (analog / driver) signals, - TSVs that only serve to transmit NV (digital) signals and - TSVs that only carry HV (analog / driver) signals.

[0113] Further advantages, details, and special features of the invention will become apparent from the description of exemplary embodiments with reference to the drawings, in which: Fig. 1 a schematic representation of a projection exposure system and its components, Fig. 2 a schematic representation of an optical component with an actuator device and a sensor device, Fig. 3 an alternative representation of the optical component according to Fig. 2, in which the mirror plate with the counter electrodes or shielding elements arranged on it is folded to the side, Fig. 4 schematically shows a cross-section through a micromirror with a stacked arrangement of electronic components, Fig. 5 schematically shows a cross-section through a micromirror with a further stacked arrangement of electronic components, Fig. 6 schematically shows a cross-section through a micromirror with yet another stacked arrangement of electronic components, Fig. 7 schematically shows a cross-section through a micromirror with a further stacked arrangement of electronic components, Fig. 8A to 8G schematically show the processing steps for producing an LTCC carrier with built-in chips, Fig. 9 schematically shows a cross-section through a mirror that images part of the signal flow on the array, Fig. 10 schematically shows a cross-section through a mirror array, illustrating some features of the 3D architecture of the electronics, Fig. 11A to 11G schematically show a manufacturing process for an electronic component in which a silicon via is first produced and then ASICs, Fig. 12A to 12G schematically show a manufacturing process for an electronic component in which an ASIC is first processed and then silicon vias are created, Fig. 13A to 13K schematically show a process flow for creating a combined architecture with ASICs, poly-Si-silicon vias and copper-silicon vias, Fig. 14 schematically shows a cross section through a micromirror with a further stacked arrangement of electronic components and Fig. 15 an exploded view of the stacked arrangement according to Fig. 14 to highlight the different sub-substrates.

[0114] First, the general structure of a projection exposure system 1 (also called a lithography system) and its components are described. For details in this regard, reference is made to WO 2010 / 049076 A2, which is hereby incorporated in its entirety into the present application as part thereof. The description of the general structure of the projection exposure system 1 is primarily to be understood as exemplary. It serves to explain a possible application of the subject matter of the present invention. The subject matter of the present invention can also be used in other optical systems, in particular in alternative variants of projection exposure systems.

[0115] Fig. Figure 1 schematically shows a microlithographic projection exposure system 1 in a meridian section. An illumination system 2 of the projection exposure system 1 comprises, in addition to a radiation source 3 (also called illumination source), an optical illumination unit 4 (also called illumination optics) for illuminating an object field 5 in an object plane 6. The object field 5 can be rectangular or arcuate with an x / y aspect ratio of, for example, 13 / 1. In this case, a reflective mask (in Fig. 1 not shown) is exposed, which carries a structure to be projected by the projection exposure system 1 for the production of micro- or nanostructured semiconductor components. An optical projection unit 7 (also called projection optics) serves to image the object field 5 into an image field 8 in an image plane 9. The structure on the mask is imaged onto a light-sensitive layer of a wafer, which is not shown in the drawing and is arranged in the region of the image field 8 in the image plane 9.

[0116] The mask, which is held by a mask holder (not shown), and the wafer, which is held by a wafer holder (not shown), are scanned synchronously in the y-direction during operation of the projection exposure system 1. Depending on the image scale of the optical projection unit 7, it is also possible for the mask to be scanned in the opposite direction relative to the wafer.

[0117] Radiation source 3 is an EUV radiation source with emitted useful radiation in the range between 5 nm and 30 nm. This can be a plasma source, for example, a GDPP (Gas Discharge Produced Plasma) source or an LPP (Laser Produced Plasma) source. Other EUV radiation sources, such as those based on a synchrotron or a free-electron laser (FEL), are also possible.

[0118] The EUV radiation 10 emerging from the radiation source 3 is focused by a collector 11. A corresponding collector is known, for example, from EP 1 225 481 A2. Downstream of the collector 11, the EUV radiation 10 passes through an intermediate focal plane 12 before impinging on a field facet mirror 13. The field facet mirror 13 is arranged in a plane of the optical illumination unit 4 that is optically conjugate to the object plane 6. The field facet mirror 13 can be arranged at a distance from a plane conjugate to the object plane 6. In this case, it is generally referred to as the first facet mirror.

[0119] The EUV radiation 10 is also referred to below as useful radiation, illumination radiation or imaging light.

[0120] Downstream of the field facet mirror 13, the EUV radiation 10 is reflected by a pupil facet mirror 14. The pupil facet mirror 14 is located either in the entrance pupil plane of the optical projection unit 7 or in a plane optically conjugate thereto. It can also be arranged at a distance from such a plane.

[0121] The field facet mirror 13 and the pupil facet mirror 14 are constructed from a plurality of individual mirrors, which are described in more detail below. In this case, the field facet mirror 13 can be subdivided into individual mirrors such that each of the field facets that illuminate the entire object field 5 itself is represented by exactly one of the individual mirrors. Alternatively, it is possible to construct at least some or all of the field facets from a plurality of such individual mirrors.

[0122] The same applies to the design of the pupil facets of the pupil facet mirror 14 assigned to the field facets, which can each be formed by a single individual mirror or by a plurality of such individual mirrors.

[0123] The EUV radiation 10 impinges on the two facet mirrors 13, 14 at a defined angle of incidence. In particular, the two facet mirrors are exposed to EUV radiation 10 in the region of normal incidence, i.e., at an angle of incidence less than or equal to 25° to the mirror normal. Exposure at grazing incidence is also possible. The pupil facet mirror 14 is arranged in a plane of the optical illumination unit 4 that represents a pupil plane of the optical projection unit 7 or is optically conjugated to a pupil plane of the optical projection unit 7. With the aid of the pupil facet mirror 14 and an imaging optics in the form of an optical transfer unit 15 with mirrors 16, 17 and 18, which are designated in the order of the beam path of the EUV radiation 10, the field facets of the field facet mirror 13 are imaged in an overlaid manner in the object field 5.The last mirror 18 of the optical transfer unit 15 is a grazing incidence mirror. The optical transfer unit 15, together with the pupil facet mirror 14, is also referred to as a sequential optical unit for transmitting the EUV radiation 10 from the field facet mirror 13 into the object field 5. The illumination light 10 is guided from the radiation source 3 to the object field 5 via a plurality of illumination channels. Each of these illumination channels is assigned a field facet of the field facet mirror 13 and a pupil facet of the pupil facet mirror 14, with the pupil facet being arranged downstream of the field facet. The individual mirrors of the field facet mirror 13 and the pupil facet mirror 14 can be tilted by an actuator system so that a change in the assignment of the pupil facets to the field facets and, accordingly, a changed configuration of the illumination channels can be achieved.This results in different illumination settings which differ in the distribution of the illumination angles of the illumination light 10 across the object field 5.

[0124] To facilitate the explanation of the positional relationships, a global Cartesian xyz coordinate system is used below. The x-axis runs perpendicular to the drawing plane in the direction of the observer in Fig. 1. The y-axis runs in Fig. 1 to the right. The z-axis runs in Fig. 1 up.

[0125] Different illumination systems can be achieved by tilting the individual mirrors of the field facet mirror 13 and correspondingly changing the assignment of these individual mirrors of the field facet mirror 13 to the individual mirrors of the pupil facet mirror 14. Depending on the tilt of the individual mirrors of the field facet mirror 13, the individual mirrors of the pupil facet mirror 14 newly assigned to the individual mirrors are adjusted by tilting, thus ensuring that the field facets of the field facet mirror 13 are again imaged into the object field 5.

[0126] Further aspects of the optical illumination unit 4 are described below.

[0127] The field facet mirror 13 in the form of a multi- or micro-mirror array (MMA) is an example of an optical assembly for guiding the useful radiation 10, i.e., the EUV beam. The field facet mirror 13 is designed as a microelectromechanical system (MEMS). The field facet mirror 13 is composed of several hundred MEMS MMA (micro mirror array) or MMA components. Each MMA has a plurality of individual mirrors 20 arranged in a matrix-like manner in rows and columns in a mirror array 19. Another arrangement is also possible, for example, hexagonal. The mirror arrays 19 can be of modular design. They can be arranged on a support structure designed as a base plate. In this case, it is possible to arrange essentially any number of the mirror arrays 19 next to one another. Thus, the total reflection surface formed by the entirety of all mirror arrays 19, in particular their individual mirrors 20, can be expanded as desired.In particular, the mirror arrays are designed to enable a substantially gap-free tessellation of a plane. The ratio of the sum of the reflection surfaces 26 of the individual mirrors 20 to the total area covered by the mirror arrays 19 is also referred to as the integration density or fill factor. In particular, this integration density is at least 0.5, in particular at least 0.6, in particular at least 0.7, in particular at least 0.8, in particular at least 0.9.

[0128] The mirror arrays 19 are attached to the base plate by means of fastening elements 29. For details, see WO 2012 / 130768 A2, for example.

[0129] The individual mirrors 20 are designed so that they can be tilted by an actuator system, as explained further below. In total, the field facet mirror 13 has approximately 100,000 individual mirrors 20. Depending on the size of the individual mirrors 20, the field facet mirror 13 can also have a different number of individual mirrors 20. The number of individual mirrors 20 of the field facet mirror 13 is in particular at least 1,000, in particular at least 5,000, in particular at least 10,000. It can be up to 100,000, in particular up to 300,000, in particular up to 500,000, in particular up to 1,000,000.

[0130] A spectral filter can be arranged in front of the field facet mirror 13 and separates the useful radiation 10 from other wavelength components of the emission of the radiation source 3 that are not usable for projection exposure. The spectral filter is not shown.

[0131] The field facet mirror 13 is illuminated by useful radiation 10 with a power of, for example, 840 W and a power density of 6.5 kW / m 2 applied.

[0132] The entire individual mirror array of the facet mirror 13 has, for example, a diameter of 500 mm and is densely packed with the individual mirrors 20. Insofar as each field facet is realized by exactly one individual mirror, the individual mirrors 20 represent the shape of the object field 5, apart from the scaling factor. The facet mirror 13 can be formed from 500 individual mirrors 20, each representing a field facet and having dimensions of approximately 5 mm in the y-direction and 100 mm in the x-direction. Alternatively to realizing each field facet by exactly one individual mirror 20, each of the field facets can be approximated by groups of smaller individual mirrors 20. For example, a field facet with dimensions of 5 mm in the y-direction and 100 mm in the x-direction can be constructed from a 1 × 20 array of individual mirrors 20 with dimensions of 5 mm × 5 mm up to a 10 × 200 array of individual mirrors 20 with dimensions of 0.5 mm × 0.5 mm.

[0133] To change the illumination settings, the tilt angles of the individual mirrors 20 are adjusted. In particular, the tilt angles have a displacement range of at least ± 50 mrad, in particular at least ± 100 mrad, in particular at least ± 120 mrad. When adjusting the tilt position of the individual mirrors 20, an accuracy of better than 0.2 mrad, in particular better than 0.1 mrad, is achieved. When adjusting the tilt position of the individual mirrors 20, an accuracy of better than 0.1 mrad, in particular better than 0.05 mrad, in particular better than 0.02 mrad is required. The individual mirrors 20 of the field facet mirror 13 and the pupil facet mirror 14 carry, in the embodiment of the optical illumination unit 4 according to Fig. 1 Multiple coatings to optimize their reflectivity at the wavelength of the useful radiation 10. The temperature of the multiple coatings should not exceed 1425 K during operation of the projection exposure system. This is achieved by a suitable design of the individual mirrors 20. For details, reference is made to DE 10 2013 206 529 A1, which is hereby incorporated in its entirety into the present application.

[0134] The individual mirrors 20 of the optical illumination unit 4 are accommodated in an evacuable chamber 21, the boundary wall 22 of which Fig. 2. The chamber 21 is connected to a vacuum pump 25 via a fluid line 23, which houses a shut-off valve 24. The operating pressure in the evacuatable chamber 21 is a few Pascals, specifically 3 Pa to 5 Pa (partial pressure H2). All other partial pressures are well below 1 × 10 -7 mbar.

[0135] The mirror with the plurality of individual mirrors 20, together with the evacuable chamber 21, forms an optical assembly for guiding a beam of EUV radiation 10.

[0136] Each of the individual mirrors 20 can have a reflection surface 26 with dimensions of 0.1 mm × 0.1 mm, 0.5 mm × 0.5 mm, 0.6 mm × 0.6 mm, or even up to 5 mm × 5 mm or larger. The reflection surface 26 can also have smaller dimensions. In particular, it has side lengths in the µm range or in the low mm range. The individual mirrors 20 are therefore also referred to as micromirrors. The reflection surface 26 is part of a mirror substrate 27 of the individual mirror 20. The mirror substrate 27 bears the multi-coating.

[0137] With the help of the projection exposure system 1, at least a portion of the mask is imaged onto a region of a light-sensitive layer on the wafer for the lithographic production of a micro- or nanostructured component, in particular a semiconductor device, for example a microchip. Depending on the configuration of the projection exposure system 1 as a scanner or as a stepper, the mask and the wafer are moved in a temporally synchronized manner in the y-direction, continuously in scanner mode or stepwise in stepper mode.

[0138] Further details and aspects of the mirror array 19, in particular the optical components comprising the individual mirrors 20, are described below.

[0139] First, with reference to the Fig. 2 and Fig. 3 describes a first variant of an optical component 30 which comprises an individual mirror 20 and in particular the displacement device 31 for displacing, in particular for pivoting, the individual mirror 20.

[0140] The representation according to Fig. 3 corresponds to that according to Fig. 2, where Fig. 3, the mirror substrate 27 of the individual mirror 20 is folded to the side. This makes the structures of the displacement device 31 and the sensor device more visible.

[0141] The optical component comprises the individual mirror 20, which is designed, in particular, as a micromirror. The individual mirror 20 comprises the above-described mirror substrate 27, on the front side of which the reflection surface 26 is formed. The reflection surface 26 is formed, in particular, by a multilayer structure. It has, in particular, a radiation-reflecting property for the illumination radiation 10, in particular for EUV radiation.

[0142] According to the variant shown in the figures, the reflection surface 26 has a square design; however, it is shown partially sectioned to also show the actuator system. It generally has a rectangular configuration. It can also have a triangular or hexagonal shape. In particular, it has a tile-like configuration that allows gap-free tessellation of a plane across the individual mirrors 20. The individual mirror 20 is attached by means of a joint 32, which will be described in more detail below. In particular, it is mounted in such a way that it has two degrees of freedom of tilt. In particular, the joint 32 enables the individual mirror 20 to be tilted about two tilt axes 33, 34. The tilt axes 33, 34 are perpendicular to each other. They intersect at a central intersection point, which is referred to as the effective pivot point 35.

[0143] As long as the individual mirror 20 is in a non-pivoted neutral position, the effective pivot point 35 lies on a surface normal 36 which passes through a central point, in particular the geometric center of gravity of the mirror surface 26.

[0144] Unless otherwise stated, the direction of the surface normal 36 in the following text is always to be understood as the direction of the same in the non-tilted neutral position of the individual mirror 20.

[0145] First, the displacement device 31 is described in more detail below.

[0146] The displacement device 31 comprises an electrode structure with actuator-converter-stator electrodes 37 i and actuator-transducer mirror electrodes 42. According to the Fig. 2 and Fig. 3, the electrode structure comprises four actuator-converter stator electrodes 371, 372, 373 and 374. In general, the number of actuator-converter stator electrodes is 37 i at least 2, but can also be 3, 4 or more.

[0147] All actuator-converter electrodes 37 i , 42 are designed as comb electrodes with a plurality of comb fingers 38. The complementary comb fingers of the mirror and stator interlock. The combs of the individual actuator electrodes 37 i Each comprises 30 actuator-converter-stator comb fingers 38, which are also abbreviated below as stator comb fingers or simply comb fingers. A different number is also possible. The number of comb fingers 38 of the actuator-converter-stator electrodes 37 i is in particular at least 2, in particular at least 3, in particular at least 5, in particular at least 10. It can be up to 50, in particular up to 100.

[0148] The combs of the actuator-converter mirror electrodes 42 accordingly consist of actuator-converter mirror comb fingers 43, which are also abbreviated below as mirror comb fingers or simply comb fingers. The number of mirror comb fingers 43 corresponds to the number of stator comb fingers. It can also differ by one from the number of stator comb fingers.

[0149] The comb fingers 38 are arranged such that they extend radially relative to the surface normal 36 or the effective pivot point 35. According to a variant not shown in the figures, the comb fingers 38, 43 can also be arranged tangentially to circles around the effective pivot point 35. They can also have an embodiment that corresponds to sections of concentric circular cylinder side surfaces around the surface normal 36.

[0150] All actuator-converter stator electrodes 37i are arranged on a support structure in the form of a substrate 39. In particular, they are arranged stationary on the substrate 39. In particular, they are arranged in a single plane defined by the front side of the substrate 39. This plane is also referred to as the actuator plane 40 or the comb plane.

[0151] A wafer serves as substrate 39. The substrate 39 is also referred to as the base plate.

[0152] The actuator-converter stator electrodes 37 i are each arranged in an area on the substrate 39, which has a square outer contour and a circular inner contour. Alternatively, the actuator-converter stator electrodes 37 ialso be arranged in a circular region on the substrate 39. In this case, the outer contour is also circular. In particular, the individual actuator-converter stator electrodes 37 i each arranged in circular segment-shaped areas. The electrode structure as a whole, ie all actuator-converter-stator electrodes 37 i , is arranged in an area having an outer contour that substantially corresponds to that of the reflection surface of the individual mirror 20. It may also be arranged in a somewhat smaller area, in particular in an area that is approximately 5% to 25% smaller.

[0153] The electrode structure has a radial symmetry. In particular, it has a fourfold radial symmetry. The electrode structure can also have a different radial symmetry. In particular, it can have a threefold radial symmetry. In particular, it has a k-fold radial symmetry, where k is the number of actuator-converter stator electrodes 37 i Apart from the subdivision of the electrode structure into the various actuator-converter-stator electrodes 37 i the electrode structure has an n-fold radial symmetry, where n is exactly the total number of comb fingers 38 of all actuator-converter stator electrodes 37 i corresponds.

[0154] Apart from their different arrangement on the substrate 39, the individual actuator-converter stator electrodes 37 iidentical in design. This is not absolutely necessary. They can also have a different design. In particular, they can be designed depending on the mechanical properties of the joint 32.

[0155] The comb fingers 38 are arranged radially with respect to the effective pivot point 35 or radially with respect to the orientation of the surface normal 36 in the non-pivoted neutral state of the individual mirror 20.

[0156] For individual mirrors 20 whose mirror substrates 27 have dimensions of 1 mm x 1 mm, the comb fingers 38 have a thickness d of at most 5 µm at their outer end in the radial direction. Generally, the maximum thickness d of the comb fingers 38 at their outer end in the radial direction is in the range of 1 µm to 20 µm, in particular in the range of 3 µm to 10 µm.

[0157] The comb fingers 38 have a height h, i.e., an extension in the direction of the surface normal 36, that lies in the range of 10 µm to 300 µm, in particular in the range of 50 µm to 150 µm. Other values ​​are also conceivable. The height h is constant in the radial direction. It can also decrease in the radial direction. This allows for larger tilt angles without causing the comb fingers of the actuator mirror electrode 42 to strike the base plate.

[0158] Adjacent comb fingers 38, 43 of the actuator electrodes 37 i on the one hand, and the actuator mirror electrodes 42, on the other hand, have a minimum distance in the range of 1 µm to 20 µm, in particular in the range of 3 µm to 10 µm, in particular approximately 5 µm, in the non-pivoted state of the individual mirror 20. These values ​​can be scaled accordingly for individual mirrors 20 with smaller or larger dimensions.

[0159] This minimum distance m is the minimum distance between adjacent mirror comb fingers and stator comb fingers, measured in the neutral, non-tilted state of the individual mirror 20. The comb fingers can approach each other when the individual mirror 20 is tilted. The minimum distance m is selected such that even with maximum tilt of the individual mirror 20, no collision occurs between adjacent mirror comb fingers and stator comb fingers. Manufacturing tolerances have also been taken into account. Such manufacturing tolerances are a few micrometers, in particular a maximum of 3 µm, in particular a maximum of 2 µm, and in particular a maximum of 1 µm.

[0160] The maximum possible proximity of adjacent comb fingers 38, 43 can be easily determined from their geometric details and their arrangement, as well as the maximum possible tilt of the individual mirror 20. In the present embodiment, the maximum proximity of adjacent comb fingers 38, 43 is approximately 2 µm when the individual mirror 20 is tilted by 120 mrad. In particular, the maximum proximity is less than 10 µm, in particular less than 7 µm, in particular less than 5 µm, in particular less than 3 µm.

[0161] The actuator-converter stator electrodes 37 i each interact with an actuator mirror electrode 42. The actuator mirror electrode 42 is connected to the mirror substrate 27. In particular, the actuator mirror electrode 42 is mechanically firmly connected to the mirror substrate 27. The actuator mirror electrodes 42 form a counter electrode to the actuator converter stator electrodes 37. i. They are therefore also simply referred to as counter electrodes.

[0162] The actuator mirror electrode 42 forms a passive electrode structure. This means that the actuator mirror electrode 42 is subjected to a fixed, constant voltage.

[0163] The actuator mirror electrode 42 is complementary to the stator electrodes 37 i of the actuator-converter. It forms, in particular, a ring with actuator-converter mirror comb fingers 43, which, for simplicity, are also referred to below as mirror comb fingers or simply as comb fingers 43. The mirror comb fingers 43 of the actuator mirror electrode 42 essentially correspond in their geometric properties to the stator comb fingers 38 of the actuator-converter stator electrodes 37. i .

[0164] All comb fingers 38, 43 can have the same height, ie identical dimensions in the direction of the surface normal 36. This simplifies the manufacturing process.

[0165] In the direction of the surface normal 36, the mirror comb fingers 43 of the actuator mirror electrode 42 can also have a different height than the stator comb fingers 38 of the active actuator converter stator electrodes 37 i .

[0166] The comb fingers 38, 43 can have a height h that decreases in the radial direction. It is also possible to make the comb fingers 38, 43 shorter in the area of ​​the corners of the optical component 30 than the other comb fingers 38, 43. This allows for a larger tilt angle of the individual mirror 20.

[0167] In particular, the actuator mirror electrode 42 is designed such that one of the comb fingers 43 of the actuator mirror electrode 42 is inserted into a space between two of the comb fingers 38 of the actuator converter stator electrodes 37 i can immerse yourself.

[0168] The actuator mirror electrode 42 is electrically conductively connected to the mirror substrate 27. Its comb fingers 43 are therefore equipotential. The mirror substrate 27 is connected to the base plate with low resistance via an electrically conductive joint spring. In principle, it is also possible to electrically connect the mirror substrate, i.e. the mirror substrate 27, the actuator mirror electrodes 42, and the sensor mirror electrodes 45, individually with separate leads via the joint 32 and thus, for example, to set them to different potentials or to decouple them with regard to interference and / or crosstalk. The base plate can, but does not have to, be grounded. Alternatively, the mirror can be connected to a voltage source at a different potential via a conductive joint spring, but be electrically insulated from the mirror plate. This makes it possible to apply a fixed or variable bias voltage to the mirror.

[0169] To the actuator-converter stator electrodes 37i can be an actuator voltage U A be applied to pivot the individual mirror 20. Therefore, the actuator-converter stator electrodes 37 i also as active actuator-converter stator electrodes 37 i To apply the actuator voltage U A to the actuator-converter stator electrodes 37 i A voltage source not shown in the figures is provided. The actuator voltage U A can be up to 200 volts or more. In particular, it can be greater than 100 volts. By applying the actuator voltage U A to a selection of the actuator-converter stator electrodes 37 i The individual mirror 20 can be tilted by up to 50 mrad, in particular up to 100 mrad, in particular up to 150 mrad, from a neutral position. Alternatively, the actuators can also be controlled by a charge source (current source).

[0170] At the various actuator-converter stator electrodes 37i different actuator voltages U Ai to pivot the individual mirror 20. To control the actuator voltages U Ai A control device not shown in the figures is provided.

[0171] To tilt one of the individual mirrors 20, an actuator voltage U A to one of the actuator-converter stator electrodes 37 i At the same time, a different actuator voltage U A2 ≠ U A1 to the actuator-converter stator electrode 37 opposite the surface normal 36 j U can A2 = 0 Volt. In particular, it is possible to set the actuator voltage U A1 only to one of the actuator-converter stator electrodes 37 i while all other actuator-converter stator electrodes 37 j kept at a voltage of 0 volts.

[0172] When tilting the individual mirror 20, the comb fingers of the actuator mirror electrode 47 on one side dip deeper between the comb fingers 38 of the actuator converter stator electrode 37 i , especially in the area of ​​this actuator-converter stator electrode 37 i , at which the actuator voltage U A On the opposite side of the tilt axis 33, the actuator mirror electrode 42 is less deeply inserted into the actuator converter stator electrodes 37 j The actuator mirror electrode 42 can even be made, at least in part, from the actuator converter stator electrodes 37 j stand out.

[0173] The comb overlap, ie the immersion depth of the actuator mirror electrode 42 between the actuator converter stator electrodes 37 i, is between 0 µm and 50 µm, preferably between 5 µm and 30 µm, preferably 10 µm in the neutral position of the individual mirror 20 with a mirror dimension between 0.5 mm2 × 0.5 mm2 and 1.0 mm2 x 1.0 mm2.

[0174] When the mirror 20 is tilted by 120 mrad, the (lateral) distance between the comb fingers 43 of the actuator mirror electrode 42 and the comb fingers 38 of the actuator converter stator electrodes 37 decreases. i by a maximum of 1 µm to 10 µm or 3 µm to 7 µm relative to the neutral position. Thus, the comb fingers 43 of the actuator mirror electrode 42 and the comb fingers 38 of the actuator converter stator electrodes 37 i in each pivoting position of the mirror 20, they are spaced apart from one another, in particular without contact. In particular, the immersion depth, ie, the comb overlap, is selected to ensure this.

[0175] According to an alternative, the comb fingers 38, 43 are somewhat shorter in the outer region and therefore have a relatively small overlap, i.e., a smaller immersion depth. For example, the immersion depth in the outermost region can be approximately half as deep as the immersion depth in the inner region. This information also refers to the neutral position of the mirror 20.

[0176] The characteristics, particularly the linearity of the control, can also be influenced by making the immersion depth of the comb fingers 38, 43 dependent on their radial position. Since all actuator-converter stator electrodes 37 i are arranged in a single plane, the actuator plane 40, complex series kinematics are dispensed with. The displacement device 31 is characterized by parallel kinematics. In particular, the displacement device 31 has no movably arranged active components. All actuator-converter stator electrodes 37 i, to which the actuator voltage U A can be applied, are arranged immovably and stationary on the substrate 39. A sensor device is provided for detecting the pivoting position of the individual mirror 20. The sensor device can form a component of the displacement device 31.

[0177] The sensor device comprises sensor-converter mirror electrodes 45 and sensor-converter stator electrodes 44 i .

[0178] The sensor unit consists of four sensor-converter stator electrodes 441 to 441. For simplification, the sensor-converter stator electrodes 44 i also referred to as sensor electrodes. For control purposes, it is advantageous if the number of sensor-converter stator electrodes is 44 i almost exactly the number of actuator-converter stator electrodes 37 i The number of sensor-converter stator electrodes 44 i but can also depend on the number of actuator-converter stator electrodes 37i differ.

[0179] The sensor-converter stator electrodes 441 to 444 are in the variant according to the Fig. 2 and Fig. 3 are arranged along the diagonal of the substrate 39. In the Fig. 2 and Fig. In the variant shown in Figure 3, the sensor-converter stator electrodes 441 to 444 are arranged offset by 45° to the tilt axes 33, 34 of the joint 32.

[0180] The actuator-converter stator electrodes 37 i are arranged in quadrants 541 to 544 on the substrate 39. The sensor-converter stator electrodes 44 i are each arranged in the same quadrant 541 to 544 as one of the actuator converter stator electrodes 37 i . The actuator device 31, in particular the arrangement and design of the actuator-converter stator electrodes 37 i, has essentially the same symmetry properties as the reflection surface 26 of the individual mirror 20. The sensor device, in particular the sensor-converter stator electrodes 44 i , has essentially the same symmetry properties as the reflection surface 26 of the individual mirror 20.

[0181] Two sensor-converter stator electrodes 44 i , which are opposite each other with respect to the effective pivot point 35, are differentially connected to each other. However, such a connection is not absolutely necessary. In general, it is advantageous if two sensor electrodes 44 are opposite each other with respect to the effective pivot point 35. i are designed and arranged so that they can be read differentially.

[0182] The sensor-converter stator electrodes 44 i are designed as comb electrodes. In particular, the sensor-converter stator electrodes 44 icorresponding to the actuator-converter-stator electrodes 37 i be designed, to whose description reference is hereby made. The sensor-converter stator electrodes 44 i each comprise a sensor-converter-stator transmitter electrode 47, which is also abbreviated below as transmitter electrode, and a sensor-converter-stator receiver electrode 48, which is also abbreviated below as receiver electrode. Both the sensor-converter-stator transmitter electrode 47 and the sensor-converter-stator receiver electrode 48 have a comb structure. They consist, in particular, of a plurality of comb fingers. In particular, the comb fingers of the sensor-converter-stator transmitter electrode 47 are arranged alternately with the comb fingers of the sensor-converter-stator receiver electrode 48.

[0183] The sensor device comprises a sensor-transducer mirror electrode 45 for each of the sensor-transducer stator electrodes 44 i. According to an advantageous embodiment, the sensor-converter mirror electrodes 45 each form a shielding unit of the sensor-converter stator electrodes 44 i . The sensor-converter mirror electrode 45 comprises comb elements with a plurality of comb fingers 46. The sensor-converter mirror electrode 45 is arranged in a manner corresponding to the sensor-converter stator electrodes 44 i a matching counter electrode. In particular, the sensor-converter mirror electrodes 45 can be designed correspondingly to the actuator-converter mirror electrodes 42, to whose description reference is hereby made.

[0184] The sensor-converter mirror electrodes 45 are each firmly connected to the mirror substrate 27. They are arranged in the diagonal region of the mirror substrate 27. When the individual mirror 20 is tilted, the sensor-converter mirror electrode 45 can be inserted at different depths between the comb fingers of the sensor-converter stator electrodes 44. i, in particular between the transmitter electrode 47 and the receiver electrode 48. This results in a variable shielding of adjacent comb fingers, in particular a variable shielding of the receiver electrode 48 with respect to the transmitter electrode 47. This leads to a change in capacitance between the adjacent comb fingers of the sensor-converter stator electrodes 44 i when the individual mirror 20 is pivoted. This capacitance change can be measured. For this purpose, the inputs of a measuring device are alternately connected to the comb fingers of the sensor-converter stator electrodes 44 i tied together.

[0185] The initial immersion depth of the sensor-converter mirror electrodes 45 between the sensor-converter stator electrodes 44 i, in particular between the transmitter electrodes 47 and the receiver electrodes 48, is between 10 µm and 100 µm, in particular between 20 µm and 60 µm, and for a mirror with a size of 1 mm, preferably about 40 µm. This ensures that the comb fingers 46 still have a residual immersion depth everywhere between the transmitter electrodes 47 and the receiver electrodes 48, even in the maximum tilted pivot position, i.e. they never protrude completely. This ensures the differential sensor function over the entire tilt range. On the other hand, the immersion depth of the sensor-converter mirror electrode 45 is selected such that even in the maximum tilted pivot position of the individual mirror 20, there is no collision between the comb fingers and the substrate 39.

[0186] To measure the capacitance between the transmitter electrode 47 and the receiver electrode 48 of the sensor-converter stator electrodes 44 i an electrical voltage, in particular a sensor voltage U S, is applied to the transmitter electrode 47. In particular, an alternating voltage serves as the sensor voltage U S .

[0187] The sensor device is sensitive to the immersion depth of the comb fingers 46 between adjacent comb fingers of the sensor-transducer stator electrodes 44 i .

[0188] The sensor device is insensitive to a mere pivoting of the comb finger 46 relative to the transmitter electrode 47 and the receiver electrode 48.

[0189] The sensor device is insensitive to a lateral displacement of the shielding element, which changes its distance from the transmitter electrode 47 and the receiver electrode 48, but leaves the immersion depth of the comb finger 46 between the adjacent transmitter and receiver electrodes 47, 48 unchanged.

[0190] Further details of the sensor device are described in WO 2016 / 146541 A1, which is hereby incorporated by reference in its entirety.

[0191] The sensor-converter stator electrodes 44 i are within the ring of the actuator-converter stator electrodes 37 i In this area, the absolute movements of the comb fingers 46 in the direction parallel to the surface normal 36 are smaller than outside the ring of the actuator-converter stator electrodes 37 i The absolute range of motion refers to the distance to the effective pivot point 35.

[0192] In the embodiments shown in the figures, the sensor-converter stator electrodes 44 i in radial direction inwards over the inner contour of the actuator-converter-stator electrodes 37 i It is also possible to connect the sensor-converter stator electrodes 44 i designed so that they do not extend beyond the inner contour of the actuator-converter stator electrodes 37 i stand out.

[0193] The sensor-converter stator electrodes 44 iare designed and arranged radially to the effective pivot point 35. In particular, they have comb fingers that extend in the radial direction. This reduces the sensitivity to possible thermal expansion of the individual mirror 20.

[0194] As already explained above, due to its design, the sensor device exhibits at best a low sensitivity to parasitic movements of the individual mirror 20, in particular to displacements perpendicular to the surface normal 36 and / or rotations about the surface normal 36. Due to the shielding principle of the sensor device, it also exhibits at best a minimal sensitivity to possible thermal expansion of the individual mirror 20. Furthermore, the sensor principle is not very sensitive to thermal deformation of the mirror.

[0195] Two sensor units, each with a transmitter electrode 47 and a receiver electrode 48, are opposite one another with respect to the effective pivot point 35 and are differentially interconnected or at least differentially readable. This eliminates errors in the measurement of the position of the mirror 20, particularly due to eigenmodes of the individual mirror 20.

[0196] The active components of the sensor device are arranged on the substrate 39. This makes it possible to measure the angle of inclination of the individual mirror 20 directly relative to the substrate 39. Furthermore, by arranging the transmitter electrodes 47 and the receiver electrodes 48 on the substrate 39, the length of the signal line 56 and / or the supply lines 57 can be reduced, in particular minimized. This reduces potential interference. This ensures constant operating conditions.

[0197] The transmitter electrodes 47 are each designed as an active shield, in particular as a shielding ring, around the receiver electrodes 48. This prevents capacitive crosstalk between the actuator-converter stator electrodes 37 i and the sensor device is reduced, in particular minimized, in particular prevented.

[0198] An alternating voltage from a voltage source 48 can be applied to the transmitter electrode 47. The voltage source 58 has a low impedance. In particular, the voltage source 58 has an output impedance that, in the excitation frequency range, is less than 1 per mille of the coupling capacitances of the actuator-converter stator electrodes 37. ito the transmitter electrodes 47. The output impedance of the voltage source is less than 1 per mille of the capacitances between the transmitter electrodes 47 and the sensor-converter mirror electrodes 45 or the receiver electrodes 48. This ensures that the alternating voltage applied to the transmitter electrodes 47 is not, or at least not significantly, influenced by the variable actuator voltages U A or the variable sensor capacitance.

[0199] A network analyzer can generally be used to read the sensor transducer. This makes it possible to determine the impedance of the sensor transducer and, using a conversion factor, determine the position of the displacement of the individual mirror 20. Such a network analyzer typically consists of an excitation source, for example, the voltage source 58 described above, and a response measurement, for example, a current measurement or a measurement of the transported charge during a signal period. The network impedance and thus the sensor capacitance can be determined from the quotient of excitation voltage and current.

[0200] Two variants of joint 32 are described in more detail below.

[0201] The joint 32 can be designed as a cardan joint.

[0202] According to a first variant, the joint 32 is designed as a torsion spring element structure. In particular, it comprises two torsion springs 50, 51. The two torsion springs 50, 51 are formed integrally. They are, in particular, aligned at right angles to each other and form a cross-shaped structure 49.

[0203] The torsion springs 50, 51 have a length of approximately 100 µm, a width of approximately 60 µm, and a thickness of approximately 1 µm to 5 µm. Such torsion springs 50, 51 are suitable for individual mirrors 20 with dimensions of 0.6 mm x 0.6 mm. The dimensions of the torsion springs 50, 51 depend on the dimensions of the individual mirrors 20. In general, larger mirrors require larger, especially stiffer, torsion springs 50, 51.

[0204] The torsion spring 50 extends in the direction of the tilt axis 33. The torsion spring 50 is mechanically connected to the substrate 39. Connection blocks 52 serve to connect the torsion spring 50 to the substrate 39. The connection blocks 52 each have a cuboid shape. They can also be cylindrical, in particular circular-cylindrical. Other geometric shapes are also possible.

[0205] The connection blocks 52 are each arranged in an end region of the torsion spring 50.

[0206] In addition to connecting the joint 32 to the substrate 39, the terminal blocks 52 also serve as spacers between the torsion spring 50 and the substrate 39.

[0207] Corresponding to the connection of the torsion spring 50 to the substrate 39, the torsion spring 51 is mechanically connected to the mirror substrate 27 of the individual mirror 20. Connection blocks 53 are provided for this purpose. The connection blocks 53 correspond in design to the connection blocks 52. The connection blocks 53 are each arranged in an end region of the torsion spring 51.

[0208] In the direction of the surface normal 36, the connection blocks 53 and the connection blocks 52 are arranged on opposite sides of the cross-shaped structure 49.

[0209] The torsion springs 50, 51 of the joint 32 have a T-shaped profile in the region of the legs of the cross-shaped structure 49 adjacent to the central region. This stiffens the torsion springs 50, 51, particularly against deflections in the direction of the surface normal 36. This shifts the natural frequency of the mirror 20 in the vertical direction to high frequencies, thus achieving a frequency separation of the controlled tilting modes and the parasitic vertical oscillation modes of more than a decade in the frequency domain, which is advantageous from a control theory perspective. Furthermore, the cross-shaped stiffening element 55 can increase the thermal conductivity of the joint 32.

[0210] In principle, it is also possible to arrange a corresponding stiffening element 55 on the opposite side of the cross-shaped structure 49. In this case, the legs of the torsion springs 50, 51 have a cross-shaped cross-section.

[0211] Through a targeted design of the stiffening elements 55, the mechanical and / or thermal properties of the joint can be specifically influenced. The profile, in particular the stiffening elements 55, serve to increase the stiffness in the actuator plane. In particular, they serve to realize a binding stiffness of the individual mirror 20 relative to the base plate 39 in the horizontal degrees of freedom, i.e., during a horizontal displacement and a rotation about the vertical axis. This increases the natural frequencies of the parasitic modes of the individual mirror 20. This results in a mode spacing between the controlled tilting modes and the parasitic modes that is advantageous from a control theory perspective. In particular, the natural frequencies of the parasitic modes are preferably at least one decade higher than the actuated tilting modes.

[0212] Furthermore, the forces acting between the mirror 20 and the actuator-converter-stator comb fingers 38 and the resulting electrostatic softening (negative stiffness) are to be absorbed by the high horizontal stiffness. In particular, it can be ensured that no transverse retraction occurs from the perspective of the comb fingers 38.

[0213] The stiffening elements 55, which are also referred to as stiffening ribs, in particular as vertical stiffening ribs, serve to shift the deflection stiffness and thus to shift the natural frequency from vertical vibrations, ie vibrations in the direction of the surface normal 36, to higher frequencies.

[0214] The joint 32 is stiff with respect to rotations about the surface normal 36. The joint 32 is stiff with respect to linear displacement in the direction of the surface normal 36. In this context, stiff means that the natural frequency of the rotational oscillations about the surface normal 36 and the natural frequency of the oscillations in the direction of the surface normal are more than a frequency decade higher than the controlled modes. The controlled tilt modes of the individual mirror are particularly at frequencies below 1 kHz, in particular below 600 Hz. The natural frequency of the rotational oscillations about the surface normal 36 is more than 10 kHz, in particular more than 30 kHz.

[0215] The joint 32 has a known flexibility with regard to pivoting about the two tilting axes 33, 34. The stiffness of the joint 32 with regard to pivoting about the tilting axes 33, 34 can be influenced by a targeted design of the torsion springs 50, 51.

[0216] The joint 32, in particular the connection blocks 52, 53 and the torsion springs 50, 51, serve to dissipate heat from the mirror substrate 27. The components of the joint 32 form heat conduction sections.

[0217] The joint 32 with the connection blocks 52, 53 performs a variety of functions. First, the connection of the uncontrolled degrees of freedom; second, the heat transfer from the mirror 20 to the base plate 39; and third, the electrical connection between the mirror 20 and the base plate 39. The blocks 52, 53 primarily serve to create space for the vertical movement of the joint element. It goes without saying that the blocks 52, 53 must also assume the mechanical, thermal, and electrical functions of the springs 50, 51.

[0218] The base plate 39 can form a heat sink. It is also possible to provide a separate heat sink. Such a heat sink is preferably thermally connected to the base plate 39, in particular to the mirror 20.

[0219] The torsion springs 50, 51 consist of a material with a thermal conductivity coefficient of at least 50 W / (mK), in particular of at least 100 W / (mK), in particular of at least 140 W / (mK).

[0220] The torsion springs 50, 51 can be made of silicon or a silicon compound. The joint 32 is preferably made of highly doped monocrystalline silicon. This allows for process compatibility with established MEMS manufacturing processes. Furthermore, it leads to advantageously high thermal conductivity and good electrical conductivity.

[0221] At an absorbed power density of 10 kW / (m 2) and mirror dimensions of 600 µm × 600 µm, the specified values ​​of the dimensions, in particular with a thickness of the torsion springs 50, 51 of 4 µm, and the thermal conductivity of the torsion springs 50, 51, result in a temperature difference of 11 K between the mirror substrate 27 and the substrate 39.

[0222] The torsion springs 50, 51 can also have a smaller thickness. If the torsion springs 50, 51 have a thickness of 2.4 µm, a temperature difference of 37 K results between the mirror substrate 27 and the substrate 39—assuming all other parameters are the same.

[0223] In particular, the thermal conductivity of the torsion spring is in the range of 0.5 K / kW / m 2 up to 10 K / kW / m 2, where the thermal power density refers to the average thermal power absorbed by the mirror. Such torsion springs could achieve a temperature difference between the mirror substrate 27 and the substrate 39 of less than 50 K, in particular less than 40 K, in particular less than 30 K, in particular less than 20 K.

[0224] In another variant of the joint 32, leaf springs are provided instead of the torsion springs 50, 51. For further details, reference is made to WO 2016 / 146 541 A1, which is hereby incorporated in its entirety by reference into the present application. Particular attention is drawn to the Fig. 10 of this application and the associated description.

[0225] In this variant, the joint 32 also exhibits high rigidity in the horizontal degrees of freedom. In this regard, reference is made to the description of the previous alternative. The design aspects with regard to the horizontal rigidity and the frequency spacing of the parasitic eigenmodes also correspond to those described above.

[0226] The variant of joint 32 is a cardan joint with orthogonally arranged, horizontal spiral springs designed as leaf springs. Two of the spiral springs are connected to each other via a plate-like structure, also called an intermediate plate.

[0227] Joint 32 offers the following advantages: It is soft in the direction of control. It is very stiff in the restricted degrees of freedom (DoF). It enables clear delineation of the eigenmodes. It leads to a virtually perfect separation of the Rx and Ry tilts.

[0228] Horizontal leaf springs are advantageous from a process engineering perspective. They particularly simplify the production of joint 32.

[0229] In this variant, the connecting blocks 52, 53 are each elongated and rod-shaped. They extend essentially over the entire extent of the joint 32 in the direction of the tilt axes 33, 34.

[0230] A separating slot can be provided between each of the connecting blocks 52, 53. The joint 32 can therefore be constructed in two parts.

[0231] The joint 32 is preferably axially symmetrical with respect to the surface normal 36. It can therefore have twofold rotational symmetry. In particular, the spiral springs can each be designed to be mirror-symmetrical to the surface normal 36.

[0232] The different variants of the displacement device 31, the sensor device, the joint 32 and the other components of the optical component 30 can essentially be freely combined with one another.

[0233] According to a further variant, the actuators can also be used simultaneously as sensors. For this purpose, the actuator's tilt-angle-dependent capacitance is read at a frequency that is significantly higher, in particular by at least a decade, than the control frequency (control bandwidth). In this case, a separate sensor device can be dispensed with. It is also possible to additionally provide a separate sensor device, in particular as described above.

[0234] The displacement device 31 can preferably be manufactured using a MEMS process. In particular, it has a structure designed for production using MEMS process steps. In particular, it has predominantly, in particular exclusively, horizontal layers, which can be structured in the vertical direction.

[0235] In particular, the electrodes 37 i , 42, 44 i , 45 can be manufactured using MEMS process steps. The joint 32 can preferably also be manufactured using MEMS process steps.

[0236] The field facet mirror 13 and / or the pupil facet mirror 14 can consist of one or more MEMS multi-mirror array (MMA) modules, each comprising, for example, 24x24 micromirrors, each with its own independent electrostatic comb actuators for tilting the mirror in two orthogonal directions and comb sensors for reading the alignment. Each mirror can be equipped with two, four, or more actuators and / or two, four, or more sensors.

[0237] Further details of the micromirrors, particularly the electronic components of the micromirrors, are described below. These details can be advantageously combined with the structural details described above. However, they are independent and not necessarily linked to these details. The following exemplary embodiments also serve to illustrate various aspects of the invention. However, the invention is not limited to these examples. Any combinations between the examples or parts of the embodiments shown therein are also subject matter of the present invention.

[0238] In the example of Fig. 4, a mirror 20 is schematically shown with its mirror substrate 27 and the reflective surface 26, the comb alignment sensor 61, the comb actuator 62 and the substrate 39 of the mirror 20.

[0239] Fig. Figure 4 shows an implementation of vertical chip stacking with an active area. The active area is the area where the electronics / integrated circuits are housed. It does not include the area where the wiring and bond / bump / connect pads are located.

[0240] The substrate 39 comprises TSVs 63 (Through-Silicon-Vias 63).

[0241] On the backside of the substrate 39, two types of chips, Type 1 chips 64, also referred to as Chips_1 64, and Type 2 chips 65, also referred to as Chips_2 65, are mounted and electrically connected by bumps 66. The bumps 66 can be made of CuSn, for example.

[0242] The chips can be made of silicon. They comprise ICs (integrated circuits) formed by etching, deposition, and local doping through selective implantation, and have a resolution / features of only 10 nm to 100 nm. The chips are also referred to as ICs, dies, or wafers. The active side 67 of the chips, on which CMOS circuits are formed, is highlighted in the figures by a dashed outline. Both chips 64 and 65 have an active area.

[0243] Chips_1 64 have their active side 67 facing upward (toward mirror 20), which is connected to the actuator TSV 63 by bumps. Chips_1 64 also have through TSVs 63 that transmit the electrical signals from Chips_2 65 through Chips_1 64 to the sensor TSVs 63 and, if applicable, to the wiring pads for other structures, thus enabling vertical stacking.

[0244] In Fig. 5 schematically shows connection options for Chips_1 64 with one active area and Chips_2 65 also with one active side or Type 3 chips 68 with two active sides.

[0245] Chips_2 64 and Chips_3 68 are located behind Chips_1 63. They can be connected using interposer chips 69. Unlike in the previous example, Chips_2 and Chips_3 behind Chips_1 are not connected via TSVs in Chips_1, but rather using interposer chips 69.

[0246] The interposer chips 69 may not have active electronic circuits, but only TSVs 63 to connect the signals through the layer of chips_1 63 towards the substrate 39 of the mirror 20.

[0247] The electronics on the underlying second level can be implemented as a single chip, but also on a complete controller / CMOS wafer 70 (shown as a black dashed rectangle) and connected by the interposer chips 69.

[0248] For simplicity, the interposer chips 69 and Chip_4 68 are shown with only one bump 66. This would lead to mechanical instability.

[0249] For all metal / metal bonded or bumped chips, two rows in the x / y direction can be advantageously used.

[0250] Preferably, chips 64, 65, 68, 69 are sized to allow for machining. Smaller chips are advantageous for higher yield, but it may be better to use chips of a similar size to the MEMS mirror 20. This results in simplified stacking (fewer chips).

[0251] The TSVs 63 of the substrate 39 of the mirror 20 and those of the chips 64, 65, 68, 69 can have another important function besides the electrical one: They can conduct the heat absorbed by the mirrors 20 backward and away, keeping the mirrors 20 at an appropriate temperature, specifically below 200°C, preferably below 100°C. This ensures that the reflectivity of the coating does not decrease and extends the lifetime of the mirror 20. This point is particularly important for EUV systems, where even the best coatings reflect only about two-thirds of the incident radiation.

[0252] Depending on the material of the TSV 63 and its insulation from the chip substrate, the TSVs 63 can have thermal, electrical or both conduction functions.

[0253] Accordingly, the bumps 66 or the connecting areas can be made of thermally, electrically or thermally and electrically conductive material.

[0254] In the embodiment according to Fig. 5, both possibilities are schematically illustrated, in which the TSVs 63 and the corresponding bumps 66_1 are considered to be electrically conductive in order to transfer the electrical signals from the back to the front of the chips_2 64, while the TSVs 63 and the bumps 66_2 are provided to transfer the heat to a heat sink 71 (or another large thermal reservoir).

[0255] The heat conduction structure is shown only schematically. Additional elements such as rewiring plates, mounting plates, controllers, etc., can be arranged between Chips_2 65, Chips_3 68, and the heat sink 71, ensuring the correct distribution of the electrical and thermal paths.

[0256] The TSVs 63 can be made of or contain copper, poly-Si, or other materials. Copper TSVs are particularly good thermal and electrical conductors, while poly-Si TSVs conduct electrical signals well and heat moderately well. On the other hand, poly-Si TSVs allow for subsequent high-temperature processes, for example, for the implantation and annealing of CMOS circuits.

[0257] Another important aspect is the quality of the lateral insulation of the 63-TSVs, if they serve an electrical function. 63-TSVs can be manufactured in three main steps: etching the hole using DRIE (deep reactive ion etching), insulating the sidewalls, and filling (especially with Cu / poly-Si).

[0258] When a die contains both electronics and TSVs, the processes must match the overall thermal budget, requiring that the highest thermal steps, such as dry thermal oxidation (high-voltage (HV) insulation) and highly doped implantation and annealing (at temperatures ranging from approximately 1000°C to 1100°C), be performed first. This is followed by lower-temperature processes, such as wet oxidation, implantation and annealing of (piezo) resistors, etc., at approximately 950°C, followed by LPCVD (low-pressure chemical vapor deposition) coating at 650-800°C for medium-quality insulation at moderate temperatures. Al deposition and annealing for contacts and wiring occurs at 420°C to 450°C.PECVD (plasma-enhanced chemical vapor deposition) of dielectrics also occurs at lower temperatures of approximately 250°C to 400°C and is used for passivation and low-voltage insulation (up to 200 V). The lower the deposition temperature of the insulation, the worse its dielectric strength (breakdown voltage). Therefore, TSVs fabricated after the CMOS part have lower insulation properties and are suitable for the low-voltage (digital) part and thermal conductivity. High-voltage drivers should be placed on the side of the chips facing the mirrors 20 (e.g., on Type 1 chips 64) and not routed through hybrid chips with CMOS and TSVs. The power supply for the HV digital-to-analog converters (DACs) can be connected from the rear via poly-Si TSVs or generated on-chip by a cascade of lower voltages.

[0259] The Fig. The Chips_3 68 shown in Figure 5 have both sides as active electrical surfaces 67. The signals generated from the back of Chips_3 68 are routed to the front side through the TSVs in the same Chips_3 68—the electrical TSVs (66_1). The electrical path then runs through the interposer chips 69 and the TSVs in the mirror substrate.

[0260] Chips_3 68 with double-sided active electrical area / electronics can be implemented by double-sided CMOS processing of the Si wafers or by back-to-back connection of two single-sided chips, e.g., by adhesive or adhesive tape.

[0261] Another solution for connecting chips is in Fig. 6. Here, a portion of the signals formed on the back of Chips_3 68 are connected by wire bonds 72 to the back of Chips_1 64, where they can be processed and / or further transmitted, e.g., to the top of Chips_1 64 for further processing or to the mirror substrate 27.

[0262] The electrical connections can be designed so that the signal can be routed through the chips to one or more wiring / stacking levels through TSVs and bumps and wire bonding.

[0263] Other contacts on the back of Chips_3 68 are wire-connected to the designated pads 73 on the mirror substrate 27. The signals from the front of Chips_3 68 can be connected to the back of Chips_1 64 or routed through Chips_1 64, as shown in Fig. 6 is shown schematically.

[0264] In the Fig. In the example shown in Figure 6, Chips_1 64 also have two active sides 67.

[0265] The structures from the top side are applied to the mirror substrate 27 with bumps.

[0266] The structures from the back are routed to the opposite side of the chip via TSVs 63.

[0267] A Chip_4 74 is shown as a single-sided active flip chip that is connected to the substrate 27 of the mirror element via bumps 66 or by metal-to-metal bonding.

[0268] Another example is in Fig. 7. Here, the chips 75 are installed in a carrier 76.

[0269] The carrier 76 can be made of ceramic, e.g., low-temperature single-fired ceramic (LTCC). This can be used for the robust assembly and packaging of electronic components, especially for multilayer packaging.

[0270] Single-fired ceramic components are manufactured using a multi-layer process. The starting material is green composite ribbons consisting of ceramic particles bonded to polymeric binders. The ribbons are flexible and can be processed, for example, by cutting, milling, punching, and embossing. Metal structures can be added to the layers, which is usually done through via filling and screen printing. Cavities are reinforced. The individual ribbons are then bonded together in a lamination process before the components are fired in a furnace, where the polymer portion of the ribbon burns and the ceramic particles sinter together, creating a hard and dense ceramic component.

[0271] The steps for producing such an LTCC carrier 76 with built-in chips 75 are described in the Fig. 8A to 8G are shown schematically.

[0272] First, a first shell 81 of the LTCC 76 is created with contact holes 77 and wire-spread layers 78 as well as cavities 79 for the first row 80 of the electronic chips 75 (cf. Fig. 8A).

[0273] The chips 75 are bonded or provided with bumps 66 (“bumped”).

[0274] Subsequently, a second LTCC shell 82 with contact holes 77, wiring layers 78 and cavities 79 is applied and electrically connected by lamination over the first shell 81 or by face-to-face bonding, bumps, etc. (see Fig. 8B).

[0275] Fine wire bonding with small wire loops is also an option, since in this case the bond pads of the chips must be located on their backside and thus must be bonded to the corresponding pads in the LTCC cavities.

[0276] The 2nd and 3rd row of chips are attached and bonded F2F (face-to-face) (see Fig. 8C), followed by the connection of the next shell 83 (cf. Fig. 8D), re-bumping / bonding of chips (cf. Fig. 8E), etc. Finally, an LTCC cap 84 can be attached (cf. Fig. 8F and Fig. 8G).

[0277] It has been recognized that higher on-die integration can be achieved by combining TSVs 63 and ASICs or other CMOS circuits on the same die (chip).

[0278] Preferably, the individual process steps are carried out in the order of decreasing process temperature.

[0279] TSVs 63 can be manufactured using the following process sequence: 1) - Etching of contact holes (DRIE), 2) - Side insulation, 3) - Filling and 4) - Planarization, in particular by chemical mechanical polishing (CMP).

[0280] The TSVs 63 can be first insulated with SiO2 and then filled with doped poly-Si or with metal, especially Cu.

[0281] Alignment mark compatibility is possible. Before or during TSV fabrication, marks are created on the wafer to align the various lithography steps. These marks ensure compatibility and fine alignment of the TSV process with the subsequent MEMS or CMOS processing.

[0282] The dielectric strength (short-circuit voltage) of the TSVs 63 side insulation can be achieved in the following ways: a) by wet thermal oxidation at 1100 °C: ~400V @ 1µm thermal SiO2 b) by PECVD (plasma-enhanced chemical vapor deposition) of SiO2 at 300 °C to 350 °C: <~100V @ 1µm PECVD SiO2

[0283] It has been found that ASICs can withstand the thermal stress and the RF and MW electromagnetic fields during the DRIE (deep RIE / reactive ion etching) process.

[0284] The TSVs 63 mentioned above can be classified according to their structure and procedure: a) TSVs as purely thermally conductive structures. No requirements for side insulation. Material: e.g., Cu. b) TSVs as thermally conductive structures and transmission of low-voltage (digital) signals. Low requirements for side insulation. Material: e.g., Cu. c) TSVs as thermally conductive structures and transmission of HV (analog / driver) signals. High demands on side insulation. A possible solution includes: poly-Si TSVs before CMOS for the HV signals and separate Cu TSVs before / after CMOS for the thermal connection. Material: poly-Si and Cu. d) TSVs are used only for transmitting low-voltage (digital) signals. Low side insulation requirements. Material: e.g., Cu or poly-Si. e) TSVs only for transmitting HV (analog / driver) signals. High demands on side insulation (only thermal oxidation, 1 µm SiO2 ~400V). Material: e.g., Cu or poly-Si. ASICs must come next.

[0285] With regard to the order of processing, the invention proposes the following: If the TSVs are processed first and then the ASICs: Isolation of TSV up to 400V, but TSV must survive all following high temperature CMOS processes TSV material: for example Poly-Si. When ASICs are processed first and then TSVs. One challenge is the direct testing of ASICs after the CMOS foundry. The ICs cannot be finished on the surface with wiring and pads, as CMP (chemical mechanical polishing) planarization for the TSVs, which is required later, would destroy them. Therefore, additional measures are necessary: ​​processing a portion of the wafers to test the ASIC yield, or including fully finished test ASICs alongside the functional chips used for intermediate testing and scratched by TSV processing. Preferably, high-temperature processes, such as thermal oxidation, are not used for the TSVs to avoid degrading the TSV insulation, which could lead to short circuits in the HVs. ASICs must survive the TSV process; DRIE with MW and RF fields, plasma, heat, gases, subsequent bonding, etc.

[0286] Three preferred solutions according to the present invention comprise the following sequence of processing steps: 1. first, poly-Si TSVs are processed and then ASICs 2. Poly-Si TSVs are provided for the HV supply for the HV / driver signals, then CMOS ASICs and finally Cu TSVs for NV and for thermal conductivity. 3. ASICs and then PECVD SiO2 / Cu TSVs are intended for the low-voltage (digital) signals and as thermally conductive structures. HV signals are generated by a cascade of low-voltage power supplies.

[0287] A particularly advantageous embodiment is in Fig. 9 and Fig. 10 shown. Fig. Figure 9 shows a schematic representation of the signals on the array for a single mirror 20.

[0288] Fig. 10 schematically shows an exemplary 3D architecture of the electronics for an array or a part thereof.

[0289] Out of Fig. 9 and Fig. 10 it can be seen that the only high voltage signal 88 (HVact i ; HVset j ) that must be passed through the stack of electronic chips (the TSVs 63*) is the high voltage supply 85 (HVsup) for the analog ASICs, which is used to build up the drive voltages for the actuators (HV driver 86).

[0290] The TSVs 63 can be connected for each actuator for each mirror from the array via bumps 66 directly to the MMA chip 87 and within the MMA chip via poly-Si TSVs.

[0291] On the top side of the middle wafer are the cores (outputs of the ADCs), which form the control voltages.

[0292] For four actuators for a synthetic mirror, four control voltages are required. For 24 x 24 mirrors, four 24 x 24 control signals are needed. They are connected via bumps to the mirror substrate and the TSVs HVact. jNo additional HV TSVs are required in the front-end ASICs.

[0293] However, these ADCs require one or two high-voltage feeds: left and right, for greater safety—provided by TSVs 63*. Only these 2 x 2 or 2 x 1 TSVs need to be high-voltage compatible. The remaining high-voltage signals are routed directly to the mirror element via the bumps.

[0294] The remaining TSVs 63 are made of Cu to transmit the amplified sensor NV signals 89 (sens i ; sense j ) to lead.

[0295] They may also have a connecting function between the front-end electronics 91 and the back-end electronics 92, in particular the controller 90.

[0296] They can also form dummy TSVs that only have a heat conduction function (thermal).

[0297] In the following, a simplified manufacturing process for chips with TSVs and CMOS circuits is described with reference to the Fig. 11A to 11G and Fig. 12A to 12G.

[0298] The Fig. 11A to 11G schematically show a simplified and shortened manufacturing process, first for TSVs and then for ASICs, in an exemplary variant.

[0299] The production of Fig. 11A starts with an init Si wafer 100.

[0300] Subsequently, alignment marks 101 are formed for different patterning levels: deposition of photoresist (PR), lithography, development, etching (RIE) of the marks in the silicon and PR stripping (see. Fig. 11B).

[0301] In step 3 (see Fig. 11C), contact holes 102 are defined lithographically and etched through using DRIE. For this purpose, the wafer can be fixed to an adhesive tape or be part of an SOI (silicon on insulator) holder wafer, which is then polished away (not shown here).

[0302] Furthermore, the wafer 100 with the contact holes 102 is oxidized for TSV isolation (formation of a thermal SiO2 layer 103 at 1100 °C (cf. Fig. 11D).

[0303] Then, the TSVs are filled by (multiple) deposition of a filler 104, which consists, for example, of highly doped poly-Si and CMP with polishing stop on the oxide (cf. Fig. 11E).

[0304] In the next step (cf. Fig. 11F), a thermal insulation 105 is applied to both surfaces. The thermal insulation 105 can be formed as a SiO2 layer deposited at 1100 °C.

[0305] This is followed by the CMOS processing for the ASICs 106, which is completed with a surface passivation using PECVD-SiO2 at 350 °C (see Fig. 11G).

[0306] The Fig. 12A to 12G schematically show a simplified and shortened manufacturing process, first for ASICs and then for TSVs in an exemplary variant.

[0307] The production process in Fig. 12 begins with the same first two steps as in Fig. 11: Init wafer 100 (cf. Fig. 12A) and lithography alignment marks 101, which are etched in Si using RIE (cf. Fig. 12B).

[0308] After that (cf. Fig. 12C), the surface is isolated by thermal oxidation (thermal SiO2 103 at 1100 °C), and the CMOS circuits (ASICs 106) are fabricated, followed by further surface isolation, in particular by low-temperature PECVD SiO2 at 350 °C.

[0309] The wafers are now ready for the formation of contact holes 102 (see Fig. 12D) TSV lithography + DRIE through the wafer. For this purpose, the wafer 100 can be fixed to an adhesive tape or be part of an SOI (silicon on insulator) holder wafer that is polished away (not shown here).

[0310] The TSVs must be isolated in the next process (see Fig. 12E). For this purpose, PECVD SiO2 is performed at 350 °C. This leaves the CMOS circuits (ASICs 106) intact.

[0311] Furthermore, the TSVs are filled with a filler 107, in particular by galvanic deposition of Cu and Cu CMP with stop on the oxide (cf. Fig. 12F).

[0312] Finally, the surface is passivated again by PECVD of SiO2 at 350 °C (cf. Fig. 12G).

[0313] Both processes are presented in an abbreviated and simplified manner. What is not shown are steps such as the formation of contacts and planar interconnects, bonding / bumping pads, etc.

[0314] The Fig. 13A to 13K schematically show the implementation of a combined solution with ASICs 106, poly-Si TSVs 104 for the HV signals and Cu TSVs 107 for the NV signals and thermal conductivity.

[0315] Processing begins as in Fig. 11A first for poly-Si TSVs and then for CMOS ASICs: Init wafer 100 (cf. Fig. 13A), alignment marks 101 (cf. Fig. 13B), DRIE for the contact holes 102 (cf. Fig. 13C), high-temperature insulation (cf. Fig. 13D), filling with highly doped poly-Si 104 and CMP (cf. Fig. 13E), surface high-temperature oxidation (cf. Fig. 13F) and formation of the CMOS part (ASIC 106) (cf. Fig. 13G). Processing then continues with steps 8 to 11, which are described in Fig. 12D to 12G, namely lithography and DRIE of the NV or thermal TSVs (cf. Fig. 13H), PECVD oxide side insulation at low temperature (cf. Fig. 13I), filling and CMP of Cu (cf. Fig. 13J) and final surface passivation at low temperature by PECVD of SiO2 at 350 °C (cf. Fig. 13K).

[0316] In the following, a further example of the arrangement of the electronic components of the micromirrors 20, in particular the front-end electronics 91 and the controller electronics 92, is described with reference to the Fig. 14 and Fig. 15 described.

[0317] The general details correspond to those of the variants described above, to which reference is made.

[0318] In the Fig. 14 and Fig. In the embodiment schematically illustrated in Figure 15, adjacent chips 205, 206; 206, 207; 207, 208 are connected to one another by bonding interface layers 209, 210, 211, 212, 213, 214. This greatly increases the contact area between adjacent chips 205, 206; 206, 207; 207, 208, in particular the contact area between the MEMS mirror chip 205 and the front-end electronics chip 206 and / or the contact area between the front-end electronics chip 206 and the controller electronics chip 207 and / or the contact area between the controller electronics chip 207 and an interposer chip 208.

[0319] The contact area between any two of these adjacent structures may be at least 50%, in particular at least 70%, in particular at least 90% of their cross-sectional area.

[0320] To distinguish between the interposer chip 69 and the interposer chip 208, the latter is also referred to below simply as interposer 208.

[0321] The chips 205, 206, 207 between the mirror substrate 27 and the interposer 208 are preferably thin. In particular, they can have a thickness of at most 100 µm. Their thickness can, for example, be in the range of 50 µm to 200 µm.

[0322] Chips 205, 206, 207, and 208 may be flexible to allow for out-of-plane bending and twisting. In particular, they may be reversibly deformable.

[0323] These chips 205, 206, 207, and 208 are connected to each other by hybrid bonding. In particular, they may have one or more full-surface connections.

[0324] This significantly reduces the vertical thermal resistance. The main function of the TSVs and the electrical bond pads is to form an electrical contact and a vertical path for signal flow. The mechanical and / or thermal connection between adjacent chips 205, 206, 207, 208 can be established across the entire lateral extent of the chips 205, 206, 207, 208. In particular, the dielectric regions can also contribute to the mechanical and / or thermal connection between adjacent chips. This allows for very low thermal resistance to be achieved. Furthermore, the thermal resistance can be kept very homogeneous across the lateral extent of the chips 205, 206, 207, 208.

[0325] With regard to the mechanical stability of the micromirrors 20, in particular their precise positioning, in particular relative to the tilt axes, they are related to the underlying support structure 60.

[0326] The arrangement of the stacked chips can be decoupled from the carrier structure 60 at least partially, in particular predominantly, in particular completely, by means of the interposer 208.

[0327] For details of the interposer 208, reference is made to DE 10 2022 209 935.4, which is incorporated by reference in its entirety. The details of the interposer 208 can also be advantageously combined with the details of other variants of the present application, in particular other variants of the stacked arrangement of electronic components.

[0328] As in the Fig. 14 and Fig. As schematically shown in Figure 15, each substrate (chip) can be provided with one or more interconnect layers 201 and its front side. The interconnect layers 201 can serve for the lateral flow of electrical signals and / or for connecting the electrical components and the TSVs. Each of the substrates (chips) may include at least one redistribution layer 202. The redistribution layer 202 may be applied to the backside of the substrate (chip). The redistribution layers 202 allow for the placement of electrical bonding sites independent of the positioning of the TSVs. In contrast to the Fig. 14 and Fig. 15, the bonding points, especially the Cu-Cu bonding points, do not have to be arranged above the areas where the electronic components are positioned. In particular, the bonding points can be shifted laterally relative to the areas where the electronic components are arranged.

[0329] Preferably, the Cu-Cu bonding points are arranged laterally offset from the electronic components of the electronic component layers 203.

[0330] This increases the robustness and reliability of the arrangement.

[0331] The substrates (chips) may further contain one or more electronic component layers 203.

[0332] The electronic circuits of the controller electronics 92 can be integrated into the controller electronics chip 207. In particular, they can be contained in the electronic component layers 203 of the controller electronics chip 207.

[0333] The electronic circuits of the front-end electronics 91 can be integrated into the front-end electronics chip 206. In particular, they can be contained in the electronic component layers 203 of the front-end electronics chip 206.

[0334] Additional electronic circuits can be integrated into the interposer 69. In particular, they can be integrated into the layout of the electronic components 203 of the interposer 69.

[0335] The interconnect layers 201 can provide lateral distribution of signals within a substrate (chip).

[0336] The chips can span the area of ​​an array of mirrors 20. In particular, the chips can have lateral dimensions that correspond to at least twice, in particular at least four times, in particular at least six times, in particular at least ten times the diameter of a single mirror substrate 27.

[0337] Even though the planar connection between adjacent substrates can lead to advantages with regard to the mechanical and / or thermal conductivity of adjacent substrates, in addition to one or more planar connections, connections by bumps 66 and / or wire connections 72 as described above are also possible.

Claims

[1] Microelectromechanical system (MEMS) for a device with one or more optical components (20) with 1.1 a suspension for an optical component (20), 1.

2. one or more actuator elements (62) for displacing the optical component (20) and / or one or more sensor elements (61) for detecting a displacement of the optical component (20) and 1.

3. a variety of integrated circuits (ICs) (64, 65, 68), 1.

4. wherein the integrated circuits (64, 65, 68) are arranged in a stacked manner and 1.

5. wherein the integrated circuits (64, 65, 68) 1.5.

1. at least two different types from the following list: actuator electronics, sensor electronics and control electronics and / or 1.5.

2. include at least two different types of silicon vias (TSVs), characterized bythat it comprises various types of electrical connections between different ICs (64, 65, 68), wherein the types of electrical connections are selected from the list of silicon vias (63), wire bonds (72) and wire and bump connections (66). [2] Microelectromechanical system (MEMS) according to claim 1, characterized by that it comprises various ICs (64, 65, 68) having at least two different types of silicon vias (TSVs) selected from the list of - TSVs that only serve as thermally conductive structures, - TSVs, which serve as thermally conductive structures and for the transmission of low-voltage (digital) signals, - TSVs, which serve as thermally conductive structures and for the transmission of high-voltage (analog / driver) signals, - TSVs that only serve to transmit low-voltage (digital) signals and - TSVs that are used only for transmitting high voltage (analog / driver) signals are selected. [3] Microelectromechanical system (MEMS) according to claim 1 or 2, characterized by that it comprises different ICs (64, 65, 68) with at least two different types of silicon vias (TSVs) made of different materials and / or with different technologies. [4] Microelectromechanical system (MEMS) according to one of the preceding claims, with one or more interposer chips (69) which contain only connections but no active electronic circuit. [5] Microelectromechanical system (MEMS) according to one of the preceding claims, characterized bythat one or more sensor readout ASICs and / or one or more actuator drivers (86) and / or one or more control logic devices (90) are each contained on different integrated circuits, wherein these different integrated circuits are arranged stacked one behind the other. [6] Microelectromechanical system (MEMS) according to one of the preceding claims, characterized by that an IC for the actuator electronics can deliver drive signals of at least 100 V. [7] Microelectromechanical system (MEMS) according to one of the preceding claims, comprising a low-temperature single-fired ceramic (LTCC) carrier (76) comprising a plurality of shells (81, 82, 83) with contact holes 77 and / or wiring layers 78 and / or cavities 79 serving as pockets for the arrangement of chips 75, the shells (81, 82, 83) being stacked on top of one another. [8] Optical component (20) with 8.

1. a microelectromechanical system (MEMS) according to one of the preceding claims, 8.

2. wherein the MEMS is arranged entirely within a base area of the optical component (20). [9] Optical component according to claim 8, characterized by in that it comprises a mirror substrate (27) defining a reflection surface (26), wherein the reflection surface (26) has an EUV-reflecting coating. [10] Optical component according to claim 9, characterized by that it has an electrode structure with a plurality of radially arranged comb fingers and / or the mirror substrate (27) is suspended from a cardan joint. [11] Optical component according to one of claims 8 to 10, characterized by that it comprises an array of a plurality of micromirrors (20). [12] Illumination optics (4) for a lithography system (1) with one or more optical components according to claim 9. [13] Lighting system (2) with 13.1 a lighting source (3) and 13.

2. an illumination optics (4) according to claim 12. [14] Projection optics (7) for a lithography system (1) with one or more optical components according to claim 9. [15] Lithography system (1) with one or more optical components according to one of claims 9 to 11.

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