MEMS micromirror array chip, MEMS micromirror array module and optical scanning equipment

Abstract

The invention provides an MEMS (Micro Electro Mechanical System) micromirror array chip, a module and optical scanning equipment. The MEMS micromirror array chip comprises a plurality of micromirror structures, a substrate, a vertical lead structure and a capacitance angle sensing structure, according to the micro-mirror array chip integrated with the capacitive sensor, array-level real-time angle detection, feedback control and high-precision scanning angle detection are realized, and the micro-mirror array chip is fast in driving and resistant to interference; meanwhile, the wiring density is reduced by frequency division multiplexing isolation signals; in addition, the application of a monolithic integrated capacitance angle sensor in a high-density micro-mirror array chip is realized by a thick substrate with a silicon through hole; and finally, the micromirror array chip of the monolithic integrated capacitance angle sensor is used for precision optical scanning equipment, a photoelectric angle detector is omitted, optical scanning high-precision real-time angle detection and feedback control, high-precision angle detection and high-speed scanning are realized, the use design is convenient, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the fields of semiconductor integrated circuit manufacturing technology and optical technology, and in particular relates to MEMS micromirror array chips, modules and optical scanning equipment. Background Technology

[0002] MEMS micromirror arrays are MEMS devices that integrate micro-actuators and micro-mirrors onto a single chip using MEMS technology. They offer fast and high-precision beam pointing and scanning capabilities. With the development of optical MEMS technology, the trends in MEMS micromirror array development include increasing array size, improving scanning accuracy, accelerating scanning speed, and developing various optical scanning devices for application in related optical systems, such as lithography machines, optical switches, and vector optical phased arrays.

[0003] The primary optical function of MEMS (Micromirror System) arrays is to perform dual-axis angle scanning of the array beam. In high-precision beam scanning applications such as lithography machine free-pupil generation devices, all-optical switching matrices, and vector optical phased arrays, scanning angle accuracy is a key technical indicator, requiring constant maintenance of optical scanning angle accuracy while performing rapid scanning (millisecond-level). However, the scanning accuracy of MEMS micromirror array chips is inevitably affected by MEMS chip manufacturing deviations and inconsistencies, scanning dynamic response, scanning characteristic drift, and environmental vibrations and temperature variations. The most effective solution is to perform real-time monitoring and feedback control of the MEMS micromirror array's scanning angle. This requires providing a high-precision, high-bandwidth scanning angle detection signal as the monitoring and control signal for MEMS micromirror scanning. However, current MEMS micromirror array technology cannot yet achieve high-precision, real-time angle detection and feedback control to obtain high-precision beam scanning.

[0004] To monitor and control the angular position of MEMS micromirror array chips, current technologies in high-precision scanning applications such as lithography machine free pupil generation devices and all-optical switching matrices typically use an additional photoelectric angular position detector to detect the scanning angle (micromirror angular position). However, due to the low bandwidth of the angular position signal output by the photoelectric angular position detector, it is impossible to simultaneously detect the angles of all micromirrors in the micromirror array at once; multiple measurements must be performed in a time-division manner. Therefore, real-time monitoring and feedback control of the angular position of micromirrors in the MEMS micromirror array chip cannot be achieved. At the same time, the photoelectric angular position detector requires a large equipment volume, affecting the spatial design flexibility of optical equipment. Furthermore, the MEMS micromirror array chip and module also require high-precision scanning characteristic calibration of each micromirror before application to the equipment, resulting in a long detection cycle, low detection efficiency, and high cost. The photoelectric angular position detector performs scanning angular position detection of MEMS micromirror arrays in multiple time-division multiple times. The detection time is long, and the detection accuracy is easily affected by environmental interference such as vibration and temperature changes during the detection interval. It is difficult to adapt to the application of equipment such as free pupil generation devices with increasingly high accuracy requirements. In particular, it cannot meet the real-time requirements of scanning feedback control of MEMS micromirror arrays. Moreover, the photoelectric angular position detector itself has many shortcomings such as high cost, large power consumption, immature technology of the array semiconductor laser used, and difficulty in optical alignment.

[0005] Therefore, there is an urgent need for a MEMS micromirror array and optical scanning device that can achieve high-precision and high-efficiency real-time monitoring and feedback control of the scanning angle position.

[0006] It should be noted that the above introduction to the technical background is only for the purpose of providing a clear and complete explanation of the technical solutions of this application and facilitating the understanding of those skilled in the art. It should not be assumed that the above technical solutions are known to those skilled in the art simply because these solutions have been described in the background section of this application. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide MEMS micromirror array chips, modules and optical scanning devices to solve the problems of low angle detection efficiency and poor accuracy of micromirror arrays and optical scanning devices in the prior art.

[0008] To achieve the above objectives, the present invention provides a MEMS micromirror array chip, the MEMS micromirror array chip comprising: a plurality of micromirror structures arranged in an array, a substrate, and a vertical lead structure;

[0009] Each of the micromirror structures includes a biaxial micromirror surface and an electrostatic drive structure. The biaxial micromirror surface is deflectable by the electrostatic drive structure. The electrostatic drive structure includes an inner axis driving high and low comb tooth group for driving the biaxial micromirror surface to deflect about a symmetry axis parallel to a first direction, and an outer axis driving high and low comb tooth group for driving the biaxial micromirror surface to deflect about a symmetry axis parallel to a second direction. The first direction and the second direction are perpendicular to each other and are both parallel to the biaxial micromirror surface. The inner axis driving high and low comb tooth group constitutes a set of capacitive angle sensing structures, and the outer axis driving high and low comb tooth group constitutes another set of capacitive angle sensing structures. The substrate includes an upper surface and a lower surface disposed opposite to each other. The vertical lead structure penetrates the upper surface and the lower surface of the substrate. The vertical lead structure is electrically connected to the inner axis driving high and low comb tooth group and the outer axis driving high and low comb tooth group, respectively, and the electrical connection is led out to the lower surface of the substrate.

[0010] The present invention also provides a MEMS micromirror array chip, the MEMS micromirror array chip comprising: a plurality of micromirror structures arranged in an array, a capacitor plate, a substrate and a vertical lead structure;

[0011] Each of the micromirror structures includes a biaxial micromirror surface and an electrostatic drive structure. The biaxial micromirror surface is deflectable by the electrostatic drive structure. The substrate includes an upper surface and a lower surface that are disposed opposite to each other. The capacitor plate is located on the upper surface of the substrate at a position parallel to and corresponding to the biaxial micromirror surface. The capacitor plate and the biaxial micromirror surface constitute a capacitance angle sensing structure. The vertical lead structure passes through the upper and lower surfaces of the substrate. The vertical lead structure is electrically connected to the biaxial micromirror surface, the capacitor plate, and the electrostatic drive structure, and the electrical connection is led out to the lower surface of the substrate. The biaxial micromirror surface is grounded through the vertical lead structure.

[0012] The substrate is made of silicon and has through-silicon vias. The through-silicon vias contain conductive low-resistivity silicon or metal, which constitute the vertical lead structure. The thickness of the substrate is 350 micrometers to 500 micrometers.

[0013] This invention also provides a MEMS micromirror array module, comprising any of the MEMS micromirror array chips described above, and further comprising: a capacitance sensing detection circuit chip, a driving chip, and a precision power supply chip; the electrical connection of the vertical lead structure leading to the lower surface of the substrate is electrically connected to the capacitance sensing detection circuit chip and the driving chip, and the precision power supply chip is electrically connected to the capacitance sensing detection circuit chip and the driving chip; the capacitance sensing detection circuit chip is used to input a sensing excitation signal to the capacitance angle sensing structure to measure the sensing capacitance value signal of the capacitance angle sensing structure, process the sensing capacitance value signal into current angle position information, and output the current angle position information; the driving chip is used to transmit an angle scanning driving signal to the electrostatic driving structure; and the precision power supply chip is used to provide power to the capacitance sensing detection circuit chip and the driving chip.

[0014] Optionally, when both the electrostatic drive structure and the capacitive angle sensing structure are driven by an inner shaft driving high and low comb teeth and an outer shaft driving high and low comb teeth, the sensing excitation signal input from the capacitive angle sensing detection circuit chip to the capacitive angle sensing structure and the angle scanning drive signal input from the drive chip to the electrostatic drive structure are isolated by frequency division multiplexing. The frequency of the sensing excitation signal is 100-1000 times the frequency of the angle scanning drive signal.

[0015] Optionally, the MEMS micromirror array module further includes a control chip, an interface chip, and connectors;

[0016] The connector includes an input signal channel and an output signal channel. The interface chip is electrically connected to the connector, and the control chip is electrically connected to the interface chip. The control chip is connected to the capacitive angle sensing detection circuit chip to receive the current angle position information output by the capacitive angle sensing structure and perform feedback control. The connector is connected to the control system of an external device. The control system outputs preset scanning angle position information to the control chip. The control chip combines the preset scanning angle position information output by the control system and the current angle position information output by the capacitive angle sensing detection circuit chip, and obtains a drive control signal according to a feedback control algorithm. The control chip distributes the drive control signal to the drive chips of each micromirror structure so that the drive chips output corresponding angle scanning drive signals to drive each micromirror structure, thereby performing feedback control of the scanning angle position.

[0017] The present invention also provides an optical scanning device, the optical scanning device including any of the MEMS micromirror array modules described above, the optical scanning device further including a control system, the control system being connected to the MEMS micromirror array module to input preset scanning angle position information or angle-time function curve to the MEMS micromirror array module.

[0018] Optionally, the optical scanning device is a free pupil generating device of a lithography machine. The free pupil generating device further includes an energy equalization component, a beam splitting component, a failed micromirror shielding component, a Fourier transform lens group, and a pupil surface. The energy equalization component, the beam splitting component, the failed micromirror shielding component, the MEMS micromirror array module, the Fourier transform lens group, and the pupil surface are arranged sequentially along the optical path propagation direction. The control system controls the deflection angle of the biaxial micromirror surface of the MEMS micromirror array module so that a preset pupil distribution pattern is obtained on the pupil surface.

[0019] Optionally, the optical scanning device is an all-optical switching matrix in an optical communication system. The all-optical switching matrix includes two MEMS micromirror array modules: a first micromirror array module and a second micromirror array module. The all-optical switching matrix also includes an input fiber collimator array and an output fiber collimator array. The input fiber collimator array is aligned with the first micromirror array module to emit an input collimated beam to the first micromirror array module. The output fiber collimator array is aligned with the second micromirror array module to receive the output collimated beam reflected from the second micromirror array module. The first micromirror array module transmits the switched collimated beam to the second micromirror array module. The control system controls the deflection angle of the biaxial micromirror surfaces of the first and second micromirror array modules to minimize the optical insertion loss between the input fiber collimator array and the output fiber collimator array.

[0020] Optionally, the optical scanning device is a vector optical phased array, which further includes an optical beam splitter and an optical phase shifter. The optical phase shifter performs optical phase shifting on multiple beams obtained after passing through the optical beam splitter, and the MEMS micromirror array module deflects the multiple beams after optical phase shifting at an angle. The optical phase shifter and the MEMS micromirror array module work together to adjust the light emitted from the optical beam splitter so that the light beams are coherently superimposed in the far field and scanned to the target angle.

[0021] As described above, the MEMS micromirror array chip, module, and optical scanning device of the present invention have the following beneficial effects:

[0022] This invention achieves real-time angle detection and feedback at the array level by setting up a micromirror array chip monolithically integrated with a capacitive sensor, thereby improving the accuracy and speed of micromirror array angle detection and enhancing the anti-interference capability of micromirror array angle detection against environmental factors such as vibration and temperature changes.

[0023] This invention, by combining frequency division multiplexing to isolate sensing signals and driving signals, reduces the wiring density requirements for micromirror array angle detection;

[0024] This invention satisfies the high-density wiring requirements by using a thick substrate with through-silicon vias, and realizes the feasibility of applying a dual-axis MEMS micromirror array with a single-chip integrated dual-axis capacitive angle sensing structure in an optical scanning device based on a large array of high-density micromirror array chips.

[0025] This invention applies a micromirror array monolithically integrated with a capacitive sensor to free pupil generation devices, all-optical switching matrices, and vector optical phased arrays, eliminating the need for photoelectric angle detectors used in these fields. It enables simultaneous real-time angle detection and feedback of all micromirror structures in the micromirror array, improving the scanning speed and accuracy of angle detection and adjustment in these devices, reducing device size, and increasing the efficiency of accuracy calibration and adjustment. Attached Figure Description

[0026] Figure 1 The image shown is a top view of the MEMS micromirror array chip in Embodiment 1 of the present invention.

[0027] Figure 2 The diagram shown is a top view of a single micromirror structure in a MEMS micromirror array chip according to Embodiment 1 of the present invention.

[0028] Figure 3 The image shown is a side cross-sectional view of the MEMS micromirror array chip corresponding to a single micromirror structure in Embodiment 1 of the present invention.

[0029] Figure 4 The image shown is a side cross-sectional view of the MEMS micromirror array chip corresponding to a single micromirror structure in Embodiment 2 of the present invention.

[0030] Figure 5 The image shown is a top perspective view of the capacitive angle sensing structure including a biaxial micromirror surface in the MEMS micromirror array chip of Embodiment 2 of the present invention.

[0031] Figure 6 The image shown is a top view of the capacitor plate in the MEMS micromirror array chip of Embodiment 2 of the present invention.

[0032] Figure 7 The image shown is a side cross-sectional view of the MEMS micromirror array module in Embodiment 3 of the present invention.

[0033] Figure 8 The image shown is a side cross-sectional view of the MEMS micromirror array module in an optional example of Embodiment 3 of the present invention.

[0034] Figure 9 The diagram shown is a schematic representation of the all-optical switching matrix in Embodiment 5 of the present invention.

[0035] Component designation explanation

[0036] 10. Micromirror structure; 11. Dual-axis micromirror surface; 121. Inner shaft driven high and low comb teeth assembly; 1211. Inner shaft fixed comb teeth; 1212. Inner shaft moving comb teeth; 122. Outer shaft driven high and low comb teeth assembly; 1221. Outer shaft fixed comb teeth; 1222. Outer shaft moving comb teeth; 123. Inner shaft elastic beam; 124. Outer shaft elastic beam; 125. Torsion frame; 126. Fixed frame; 127. Support frame; 13. Capacitor plate; 131. Sub-capacitor plate; 132. Air gap; 133. Insulating groove;

[0037] 21. Substrate; 22. Vertical lead structure; 221. Capacitor vertical lead; 222. Drive vertical lead; 23. Insulating oxide layer; 31. Capacitive sensing detection circuit chip; 32. Driver chip; 33. Control chip; 34. Interface chip; 35. Control and interface chip; 36. Connector; 361. FPC stripline; 37. Filter capacitor; 38. Precision power chip; 39. Adapter board; 411. First micromirror array module; 412. Second micromirror array module; 421. Input fiber collimator array; 422. Output fiber collimator array; 431. Input single-mode fiber array; 432. Output single-mode fiber array; 441. First FPC stripline; 442. Second FPC stripline; 451. Input collimated beam; 452. Output collimated beam; 453. Exchange collimated beam; 46. Optical platform panel. Detailed Implementation

[0038] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0039] In the detailed description of embodiments of the present invention, for ease of explanation, the schematic diagrams illustrating the device structure may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0040] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the accompanying drawings for devices in use or operation.

[0041] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0042] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0043] Example 1:

[0044] like Figures 1-3 As shown, this embodiment provides a MEMS micromirror array chip, wherein... Figure 1 This is a top view of a MEMS micromirror array chip. Figure 2 This is a top view of a single micromirror structure 10 in a MEMS micromirror array chip. Figure 3 The image shows a side cross-sectional view of the structure of a MEMS micromirror array chip corresponding to a single micromirror structure 10. The MEMS micromirror array chip includes: multiple micromirror structures 10 arranged in an array, a substrate 21, and a vertical lead structure 22.

[0045] Each of the micromirror structures 10 is 1 mm long and 1 mm wide. Each micromirror structure 10 includes a biaxial micromirror surface 11 and an electrostatic drive structure. The biaxial micromirror surface 11 is deflectable by the electrostatic drive structure. The electrostatic drive structure includes an inner axis driving high and low comb teeth group 121 for driving the biaxial micromirror surface 11 to deflect about a symmetry axis parallel to a first direction, and an outer axis driving high and low comb teeth group 122 for driving the biaxial micromirror surface 11 to deflect about a symmetry axis parallel to a second direction. The first direction and the second direction are perpendicular. Both the first direction and the second direction are parallel to the biaxial micromirror surface 11. The inner axis driven high and low comb teeth group 121 forms a set of capacitive angle sensing structures, and the outer axis driven high and low comb teeth group 122 forms another set of capacitive angle sensing structures. The substrate 21 includes an upper surface and a lower surface that are arranged opposite to each other. The vertical lead structure 22 passes through the upper surface and the lower surface of the substrate 21. The vertical lead structure 22 is electrically connected to the inner axis driven high and low comb teeth group 121 and the outer axis driven high and low comb teeth group 122, respectively, and the electrical connection is led out to the lower surface of the substrate 21.

[0046] Specifically, the dimensions of the micromirror structure 10 described above are merely an example, and any other suitable dimensions may be used.

[0047] In existing technologies, scanning angle detection for micromirror arrays mostly requires a separate photoelectric angle position detector to measure the angle of each micromirror in a time-division manner. Therefore, when scanning the angle of the entire micromirror array, the difference caused by external environmental vibrations and temperature changes during asynchronous detection results in poor accuracy, long detection time, and low detection efficiency. When the array size and density of micromirror arrays are large, the number and density of wiring required for the MEMS angle sensor to perform micromirror scanning angle detection are also large. Some MEMS micromirror structures that can realize capacitive angle sensing detection of a single MEMS micromirror face the problem of high-density wiring due to the capacitive angle sensing structure in high-density array applications. The implementation of high-density wiring for MEMS micromirror structures in existing processes is difficult and complex, and many process problems need to be overcome. Therefore, it is often difficult to use in practical high-density micromirror arrays, which is not conducive to the practical application and industrialization of micromirror arrays in optical scanning equipment that requires large arrays of high-density micromirror structures.

[0048] This embodiment achieves monolithic integration of the micromirrors and the capacitive angle sensing detection structure by setting the electrostatic drive structure of each dual-axis micromirror surface 11 in the micromirror array as a capacitive angle sensing structure. This allows all micromirrors in the micromirror array to perform real-time angle detection and feedback control simultaneously and independently, thereby obtaining the angle information of all micromirrors in the array simultaneously and in real time. This enables synchronous real-time detection and significantly reduces the impact of external factors such as environmental vibration and temperature changes on the accuracy of micromirror scanning angle detection. Furthermore, the structure allowing real-time synchronous measurement of all micromirrors in the array greatly improves the bandwidth and efficiency of the scanning angle detection signal. Additionally, since the capacitive angle sensing in this invention uses the electrostatic drive structure of the micromirrors, the angle sensing detection and micromirror drive share a common physical structure, which significantly reduces the wiring density required for angle sensing and achieves single-chip integrated micromirror array scanning angle detection.

[0049] In one embodiment, the substrate 21 is made of silicon, and the substrate 21 is provided with a through-silicon via (TSV) penetrating the substrate 21. The TSV contains conductive low-resistivity silicon or metal, and the conductive low-resistivity silicon or metal in the TSV constitutes the vertical lead structure 22. The thickness of the substrate 21 is 350 micrometers to 500 micrometers.

[0050] The present invention achieves high-density wiring with high yield and low cost in the MEMS micromirror array chip by using through silicon vias (TSVs) to set the vertical lead structure 22 in a thicker substrate 21. For example, a MEMS micromirror array chip containing a 32-row, 32-column micromirror structure 10 has 5120 vertical leads, which is impossible to achieve with a planar lead structure.

[0051] In current semiconductor technology, TSV technology is used to fabricate 3D CMOS integrated circuits, often to shorten the length of electrical signal traces. It utilizes thin TSV silicon substrates (30-100 micrometers) to construct dozens of layers of 3D integrated circuits. The conductive pillars in the TSV are electroplated copper to reduce the on-resistance of the electrical signal transmission path. In MEMS micromirror array chips, thicker TSV substrates are required, at least 350 micrometers thick. Otherwise, wafer fragmentation is highly likely during MEMS fabrication. The copper electroplating filling of vias in thick TSV substrates is difficult to implement, significantly increasing costs. If thinner TSV substrates (e.g., 175 micrometers thick, the maximum thickness in current technology) are used for double-layer stacking and bonding, the yield of the resulting thicker TSV substrate (350 micrometers thick) is very poor. The overall technical challenges are significant. Therefore, current technologies often avoid using copper electroplated TSV substrates to meet the wiring density requirements of MEMS micromirror arrays and also avoid integrating other functional structures, such as single-chip integrated angle sensors, into MEMS micromirror arrays to avoid a significant increase in wiring density.

[0052] This invention, from a novel perspective, utilizes the ability of low-resistivity silicon TSVs in a thicker substrate to perform downward vertical wiring, thus meeting the wiring density requirements of MEMS micromirror array chips with high-density horizontally arranged micromirror structures integrating capacitive angle sensing structures. In the invention process, this invention leverages the fact that the main body of the MEMS micromirror array chip itself is a capacitive angle sensing structure, and the on-resistance of the low-resistivity silicon conductive pillars is approximately 1Ω, negligible for capacitive sensors. This avoids the copper plating process, using low-resistivity silicon as the conductive pillars in the TSVs, thereby achieving low-cost, high-yield TSV wiring in a thicker substrate. This overcomes the technical biases caused by the cost, process, and yield difficulties of using TSV wiring in MEMS micromirror arrays in the prior art. This allows the micromirror structure 10 integrating capacitive angle sensing structures in MEMS micromirrors to be practically applied in high-density micromirror arrays, meeting the higher-density wiring requirements for further integration of capacitive angle sensors in MEMS micromirror array chips.

[0053] Specifically, the multiple micromirror structures 10 are arranged in an m×n array, including m rows and n columns of micromirror structures 10, where m and n are both integers greater than or equal to 2.

[0054] In one embodiment, such as Figure 2As shown, the micromirror structure 10 is a biaxial micromirror. The electrostatic drive structure further includes an inner axis elastic beam 123, an outer axis elastic beam 124, a torsion frame 125, a fixing frame 126, and a support frame 127. The biaxial micromirror mirror 11 is fixedly placed on the support frame 127. The support frame 127 is connected to the torsion frame 125 through the inner axis elastic beam 123. The inner axis drive high and low comb teeth group 121 is arranged opposite to each other at corresponding positions on the support frame 127 and the torsion frame 125. The inner axis drive high and low comb teeth group 121 is symmetrical about the biaxial micromirror mirror 11 in the first direction. The inner axis elastic beam 123 is symmetrically distributed with respect to the dual-axis micromirror surface 11, parallel to the axis of symmetry in the first direction. The torsion frame 125 is connected to the fixed frame 126 via the outer axis elastic beam 124. The outer axis drive high and low comb teeth 122 are arranged opposite to each other at corresponding positions on the torsion frame 125 and the fixed frame 126. The outer axis drive high and low comb teeth 122 are symmetrically distributed with respect to the dual-axis micromirror surface 11, parallel to the axis of symmetry in the second direction. The outer axis elastic beam 124 is symmetrically distributed with respect to the dual-axis micromirror surface 11, parallel to the axis of symmetry in the second direction.

[0055] Specifically, such as Figure 2 As shown, the inner shaft driven high and low comb tooth assembly 121 includes an inner shaft fixed comb tooth 1211 and an inner shaft movable comb tooth 1212. The inner shaft fixed comb tooth 1211 is located on the torsion frame 125, and the inner shaft movable comb tooth 1212 is located on the support frame 127. The outer shaft driven high and low comb tooth assembly 122 includes an outer shaft fixed comb tooth 1221 and an outer shaft movable comb tooth 1222. The outer shaft fixed comb tooth 1221 is located on the fixed frame 126, and the inner shaft movable comb tooth 1212 is located on the torsion frame 125.

[0056] In one embodiment, such as Figure 2 As shown, the inner axis elastic beam 123 is located between the support frame 127 and the torsion frame 125, corresponding to the position on the straight line where the biaxial micromirror mirror 11 is parallel to the first direction axis of symmetry. The outer axis elastic beam 124 is located between the fixed frame 126 and the torsion frame 125, corresponding to the position on the straight line where the biaxial micromirror mirror 11 is parallel to the second direction axis of symmetry.

[0057] In one embodiment, the electrostatic drive structure is driven by one or two of the following methods: electrostatic drive, electromagnetic drive, piezoelectric drive, or electrothermal drive.

[0058] This invention combines the advantages of two driving methods to drive a dual-axis micromirror via an electrostatic driving structure, thereby achieving better driving performance.

[0059] In one embodiment, the mechanical angle range of the dual-axis micromirror scanning is ±3° (i.e., ±53mrad), and its scanning optical angle range is ±6° (i.e., ±106mrad); the minimum frequency of its outer axis drive for scanning is 920Hz, and the maximum driving voltage is 56V; the minimum frequency of its inner axis drive for scanning is 1000Hz, and the maximum driving voltage is 52V.

[0060] In one embodiment, the vertical lead structure 22 corresponding to each micromirror structure 10 includes: positive and negative voltage leads Vx+ and Vx- for driving the inner shaft connected to the inner shaft fixed comb teeth 1211; a grounding wire connected to the inner shaft moving comb teeth 1212; positive and negative voltage leads Vy+ and Vy- for driving the outer shaft connected to the outer shaft fixed comb teeth 1221; and a grounding wire connected to the outer shaft moving comb teeth 1222.

[0061] In one embodiment, when the material of the substrate 21 is silicon, the substrate 21 is a single-crystal silicon wafer or a polycrystalline silicon wafer, and the material of the vertical lead structure 22 can be one of low-resistivity silicon, metal or metal alloy.

[0062] In one embodiment, when the substrate 21 is made of ceramic, it is manufactured by a low-temperature co-fired ceramic process or a high-temperature co-fired ceramic process followed by a surface precision grinding and polishing process.

[0063] In one embodiment, when the material of the substrate 21 is ceramic, the substrate 21 is formed by sintering into a composite layer consisting of a substrate 21 layer, an intermediate wiring layer, and a substrate 21 layer from top to bottom.

[0064] In one embodiment, the overall equivalent coefficient of thermal expansion (CTE) of the composite layer is 3.0-7.5 ppm / ℃. Preferably, the CTE of the composite layer is 3.0 to 5.0 ppm / ℃.

[0065] This invention sets the substrate 21 as a composite layer of ceramic including a wiring layer, and utilizes the mature layered manufacturing process of ceramics to set the wiring within the substrate 21. This saves the process of setting the wiring during the overall fabrication of the MEMS micromirror array chip, thereby improving production efficiency.

[0066] In one embodiment, the total thickness variation (TTV) of the substrate 21 is less than or equal to 3 micrometers. Preferably, the TTV of the substrate 21 is less than or equal to 1 micrometer.

[0067] This invention improves the manufacturing yield of micromirror array chips and the accuracy of micromirror angle measurement by setting the TTV range of substrate 21 and controlling the surface deviation of substrate 21.

[0068] In one embodiment, the upper and / or lower surfaces of the substrate 21 are provided with an RDL (ReDistributionLayer).

[0069] In one embodiment, a bonding pad is provided on the upper surface of the substrate 21, the bonding pad being used to bond the substrate 21 and the micromirror structure 10.

[0070] In one embodiment, a metal capacitor electrode is disposed on the upper surface of the substrate 21, and the metal capacitor electrode is used to connect the capacitive angle sensing structure and the vertical lead structure 22.

[0071] In one embodiment, the metal wiring layer, the bonding pads, and / or the metal capacitor electrodes are made of gold.

[0072] In one embodiment, the lower surface of the substrate 21 is provided with a pad UBM (Under Ball Metal), which is used for electrical connection with the adapter board 39 or other external functional chips.

[0073] In one embodiment, the material of the pad UBM is a Ti / Ni / Au stack.

[0074] In one embodiment, the surface of the substrate 21 may also be fabricated with other suitable microstructures such as capacitor electrodes, cavities or trenches, alignment marks, etc., which can be selected and adjusted as needed.

[0075] In one embodiment, the thickness of the substrate 21 is 400 micrometers, such as Figure 3 As shown, an insulating oxide layer 23 is provided on both the upper and lower surfaces of the substrate 21, and the thickness of the insulating oxide layer 23 is 2 micrometers. The redistribution layer, the bonding pad and / or the solder pad are disposed on the surface of the insulating oxide layer 23.

[0076] In one embodiment, the thickness of the substrate 21 is 300 micrometers to 750 micrometers.

[0077] In one embodiment, the substrate 21 is a 6-inch silicon wafer containing conductive pillars, the conductive pillars serve as vertical lead structures 22, the material of the conductive pillars is low-resistivity polycrystalline silicon, and the conductive pillars are surrounded by a silicon dioxide layer to insulate the conductive pillars from the silicon in the substrate 21, and the on-resistance of the conductive pillars is approximately 1Ω.

[0078] In one embodiment, the material of the vertical lead structure 22 is one of low-resistivity silicon, metal, or metal alloy, or other suitable conductive materials.

[0079] Example 2:

[0080] This embodiment provides a MEMS micromirror array chip, which has similar features to that in Embodiment 1, except that:

[0081] like Figure 4 As shown, the MEMS micromirror array chip also includes a capacitor plate 13; the capacitor plate 13 is located on the upper surface of the substrate 21 at a position parallel to and corresponding to the dual-axis micromirror surface 11, and the capacitor plate 13 and the dual-axis micromirror surface 11 form a capacitance angle sensing structure; the vertical lead structure 22 is electrically connected to the dual-axis micromirror surface 11, the capacitor plate 13, and the electrostatic drive structure respectively, and the electrical connection is led out to the lower surface of the substrate 21; the dual-axis micromirror surface 11 is grounded through the vertical lead structure 22.

[0082] In one embodiment, the substrate 21 is made of silicon, and the substrate 21 is provided with a through-silicon via (TSV) penetrating the substrate 21. The TSV contains conductive low-resistivity silicon or metal, and the conductive low-resistivity silicon or metal in the TSV constitutes the vertical lead structure 22. The thickness of the substrate 21 is 350 micrometers to 500 micrometers.

[0083] This embodiment uses a capacitor plate 13 and a biaxial micromirror surface 11 together as a capacitive angle sensing structure (i.e., a planar capacitor structure). Sharing the physical structure with the biaxial micromirror surface 11 enables scanning angle detection, achieving a similar effect to Embodiment 1 of simultaneous synchronous scanning angle detection. This significantly improves the angle detection accuracy of the micromirror array, reaching 1-200 μrad. It also enhances the real-time performance and efficiency of angle detection, with a signal bandwidth of 1-10 kHz, reducing the wiring density requirements for micromirror array angle detection. Furthermore, the TSV structure and its arrangement in the substrate 21 overcome the wiring problems of micromirror arrays integrating capacitive sensors, facilitating the practical application of micromirror structures integrating capacitive angle sensing in optical scanning devices requiring large-array, high-density micromirror arrays.

[0084] In one embodiment, the planar capacitor structure formed by the capacitor plate 13 and the biaxial micromirror 11 is only a capacitor angle sensing structure and does not serve as an electrostatic driving structure to drive the biaxial micromirror 11. The electrostatic driving structure is a comb tooth driving structure that includes an inner shaft driving high and low comb tooth group and an outer shaft driving high and low comb tooth group.

[0085] In one embodiment, the planar capacitor structure formed by the capacitor plate 13 and the biaxial micromirror 11 serves as both a capacitor angle sensing structure and an electrostatic driving structure for driving the biaxial micromirror 11. In this case, the micromirror structure does not need to be fabricated with high and low comb teeth, and the sensing signal of the planar capacitor structure and the angle scanning driving signal of the micromirror structure are frequency-division isolated by frequency division multiplexing.

[0086] Specifically, since the planar capacitor structure and the electrostatic drive structure in this embodiment do not share a physical structure, an additional capacitor plate 13 is required, thus necessitating an additional structure. Furthermore, a certain air gap 132 is needed to form a dielectric layer in order to create the planar capacitor. Therefore, compared to Embodiment 1, there is a greater space requirement. However, this allows for the creation of a sensing capacitor independent of the electrostatic drive capacitor, eliminating the need for frequency division multiplexing to isolate the angle scanning drive signal and the sensing signal. Conversely, when the planar capacitor structure and the electrostatic drive structure share a physical structure, no additional electrostatic drive structure is required, resulting in a simpler structure. However, frequency division multiplexing is still needed to isolate the angle scanning drive signal and the sensing signal. Additionally, the scanning angle range of the planar capacitor structure as an electrostatic drive structure is typically smaller, and it is also susceptible to the electrostatic pull-in effect. Overall, the effects achieved by both are similar. This embodiment is a variation of Embodiment 1, and those skilled in the art can choose according to their needs.

[0087] Specifically, such as Figure 4 As shown, the vertical lead structure 22 includes a ground lead (not shown in the figure), a capacitor vertical lead 221, and a drive vertical lead 222. The ground lead is electrically connected to the biaxial micromirror surface 11, the capacitor vertical lead 221 is electrically connected to the electrode plate, and the drive vertical lead 222 is electrically connected to the electrostatic drive structure of the micromirror structure 10.

[0088] In one embodiment, such as Figure 5 The image shown is a top perspective view of the capacitive angle sensing structure including the biaxial micromirror surface 11, as shown below. Figure 6The diagram shows a top view of the capacitor plate 13. The capacitor plate 13 is circular and divided into four sub-capacitor plates 131 of the same size. Each sub-capacitor plate 131 is a sector-shaped capacitor plate 13 with a central angle of 90°. Two dividing lines correspond to two lines that form a 45° angle with the projections of the biaxial micromirror mirror 11 (parallel to the first direction) and the biaxial micromirror mirror 11 (parallel to the second direction) onto the capacitor plate 13. Insulation between the 31 is achieved through insulating grooves 133 at the two dividing lines. Each of the sub-capacitor plates 131 is electrically connected to the lower surface of the substrate 21 through a capacitor vertical lead 221. The differential capacitance angle sensing structure formed by the two diagonally arranged sub-capacitor plates 131 and the biaxial micromirror surface 11 is used to detect the deflection angle of the biaxial micromirror surface 11 with the axis of symmetry of the biaxial micromirror surface 11 not covered by the corresponding two sub-capacitor plates 131 as the central axis.

[0089] This invention sets the sub-capacitor plate 131 in a diagonally symmetrical configuration to form a differential capacitance angle sensing structure. This allows the capacitance value obtained by the capacitance sensing detection circuit chip 31 to have a monotonic linear relationship with the scanning angle of the micromirror as close as possible. This is beneficial for improving the accuracy of the scanning angle and reducing the computational complexity of obtaining the scanning angle, thereby improving computational efficiency.

[0090] Example 3:

[0091] This embodiment provides a MEMS micromirror array module, which includes the MEMS micromirror array chip described in either embodiment 1 or 2, such as... Figure 7 As shown, the MEMS micromirror array module further includes: a capacitance sensing detection circuit chip 31, a driving chip 32, and a precision power supply chip 38; the electrical connection of the vertical lead structure 22 leading to the lower surface of the substrate 21 is electrically connected to the capacitance sensing detection circuit chip 31 and the driving chip 32, and the precision power supply chip 38 is electrically connected to the capacitance sensing detection circuit chip 31 and the driving chip 32; the capacitance sensing detection circuit chip 31 is used to input a sensing excitation signal to the capacitance angle sensing structure to measure the sensing capacitance value signal of the capacitance angle sensing structure and process the sensing capacitance value signal into current angle position information before outputting the current angle position information; the driving chip 32 is used to input a scanning angle driving signal to the electrostatic driving structure; and the precision power supply chip 38 is used to provide power to the capacitance sensing detection circuit chip 31 and the driving chip 32.

[0092] In one embodiment, the power chip 38 is used to supply the required high-precision power to each chip in the MEMS micromirror array module.

[0093] In one embodiment, the power chip 38 includes a 60V analog power chip 38, a 5V analog power chip 38, a 3.3V analog power chip 38, and a 3.3V digital power chip 38.

[0094] In one embodiment, the MEMS micromirror array module includes one MEMS micromirror array chip.

[0095] In one embodiment, the MEMS micromirror array module includes multiple MEMS micromirror array chips, which are spliced ​​together seamlessly or with seams. Specifically, in the case of seamless splicing, the distance between each MEMS micromirror array chip is no greater than the distance between its micromirror structures 10.

[0096] In one embodiment, when both the electrostatic drive structure and the capacitive angle sensing structure are inner-shaft driven high and low comb teeth 121 and outer-shaft driven high and low comb teeth 122, the sensing excitation signal input from the capacitive sensing detection circuit chip 31 to the capacitive angle sensing structure and the scanning angle driving signal input from the drive chip 32 to the electrostatic drive structure are frequency-division multiplexed, and the frequency of the sensing excitation signal is 100-1000 times the frequency of the angle scanning driving signal.

[0097] This invention employs frequency division multiplexing to achieve frequency isolation between the sensing signal and the angle control signal on the shared signal transmission lead. Combined with the physical structure of its shared electrostatic drive structure and capacitive angle sensing structure, it further reduces the volume space and line density required for scanning angle detection, solves the problem of high-density wiring technology, and is conducive to improving the reliability of the micromirror array module, while also facilitating the miniaturization of the module.

[0098] Preferably, the frequency of the sensing signal is 1000 times the frequency of the scanning angle driving signal. This invention reduces interference between the sensing signal and the scanning angle driving signal by setting the frequency of the sensing signal to be much greater than that of the scanning angle driving signal, thereby further improving the accuracy and reliability of scanning angle detection in the micromirror array.

[0099] In one embodiment, the sensing excitation signal input by the capacitance sensing detection circuit chip 31 to the capacitance angle sensing structure is a 10MHz square wave voltage signal. The capacitance angle sensing structure is connected to the 10MHz square wave voltage signal in the capacitance sensing detection circuit chip 31 to obtain the sensing capacitance value signal transmitted by the capacitance angle sensing structure. The capacitance-to-voltage conversion circuit in the capacitance sensing detection circuit chip 31 demodulates the sensing capacitance value signal transmitted by the capacitance angle sensing structure into a digital electrical signal and processes the digital electrical signal into the current angle position information.

[0100] In one embodiment, the capacitance sensing detection circuit chip 31 consists of four capacitance sensing ASIC chips, each used to detect the capacitance value corresponding to the scanning angle of the capacitance angle sensing structure in two directions in the quarter-micromirror array.

[0101] In one embodiment, the driving chip 32 consists of four 60V-driven HV-ASIC (High Voltage Application Integrated Circuit) chips, each used to drive the electrostatic driving structure of the quarter-micromirror array in two deflection directions, with a driving voltage accuracy of 12 bits.

[0102] In one embodiment, a MEMS micromirror array module comprising 11 rows and 11 columns of micromirror structures 10 has a length of less than or equal to 40 mm, a width of less than or equal to 40 mm, and a power consumption of less than or equal to 5 W.

[0103] In one embodiment, such as Figure 7 As shown, the MEMS micromirror array module also includes a control chip 33, an interface chip 34, and a connector 36;

[0104] The connector 36 includes an input signal channel and an output signal channel. The interface chip 34 is electrically connected to the connector 36, and the control chip 33 is electrically connected to the interface chip 34. The control chip 33 is connected to the capacitive angle sensing detection circuit chip 31 to receive the current angle position information output by the capacitive angle sensing structure and perform feedback control. The connector 36 is connected to the control system of an external device. The control system outputs preset scanning angle position information to the control chip 34. The control chip 34 combines the preset scanning angle position information output by the control system and the current angle position information output by the capacitive angle sensing detection circuit chip 31, and obtains a drive control signal according to the feedback control algorithm. The control chip 33 distributes the drive control signal to the drive chip 32 of each micromirror structure 10 so that the drive chip 32 outputs a corresponding angle scanning drive signal to drive each micromirror structure 10, thereby performing feedback control of the scanning angle position.

[0105] In one embodiment, such as Figure 7 As shown, the MEMS micromirror array module also includes a filter capacitor 37, which is used to decouple the precision power chip 38 from the driving chip 32, improve the power accuracy of the driving chip 32, and thus improve the scanning angle driving accuracy of the MEMS micromirror array module.

[0106] In one embodiment, the filter capacitor 37 includes four 60V capacitors, four 5V capacitors, and four 3.3V capacitors.

[0107] In one embodiment, the connector 36 transmits signals to an external device via an FPC (Flexible Printed Circuit) ribbon cable 361.

[0108] In one embodiment, such as Figure 8 As shown, the control chip 33 and the interface chip 34 can be a single integrated control and interface chip 3534 with control and interface functions.

[0109] In one embodiment, the monolithically integrated control chip 33 and interface chip 34 can be commercial FPGA (Field Programmable Gate Array) chips.

[0110] In one embodiment, the capacitive sensing detection circuit chip 31, the driving chip 32, the control chip 33, the interface chip 34, and the connector 36 are directly soldered to the lower surface of the substrate 21 of the MEMS micromirror array chip and electrically connected to the vertical lead structure 22 by flip-chip bonding.

[0111] In one embodiment, the capacitance sensing detection circuit chip 31, the driver chip 32, the control chip 33, the interface chip 34, the connector 36, and the precision power supply chip 38 are integrated into an application-specific integrated circuit (ASIC) chip. Specifically, other suitable functional chips may also be included, all of which can be integrated into an ASIC chip.

[0112] In one embodiment, such as Figure 7 As shown, the MEMS micromirror array module also includes an adapter board 39. The capacitive sensing detection circuit chip 31, the driving chip 32, the control chip 33, the interface chip 34, the connector 36, and the precision power chip 38 are soldered to the surface of the adapter board 39 by flip-chip bonding and electrically connected to the vertical lead structure 22 of the MEMS micromirror array chip to form a 2.5D package structure.

[0113] This invention enables electrical connection between other chips and MEMS micromirror array chips by setting up an adapter board 39, which simplifies the packaging process and facilitates adaptation to existing processes.

[0114] In one embodiment, the adapter plate 39 is one of a silicon substrate, a low coefficient of thermal expansion glass substrate, a ceramic substrate, a printed circuit board, or a high-density organic substrate.

[0115] In one embodiment, when the length and width of the MEMS micromirror array chip are both greater than or equal to 20 mm, the adapter plate 39 is one of a silicon substrate, a low coefficient of thermal expansion glass substrate, or a ceramic substrate, which can reduce chip warpage; when the length and width of the MEMS micromirror array chip are both less than 20 mm, the adapter plate 39 is a printed circuit board or a high-density organic substrate, which can reduce module cost.

[0116] In one embodiment, when the MEMS micromirror array module includes multiple MEMS micromirror array chips, each MEMS micromirror array chip corresponds to an adapter board 39, and multiple adapter boards 39 are spliced ​​together with the MEMS micromirror array chips.

[0117] In one embodiment, when the MEMS micromirror array module includes multiple MEMS micromirror array chips, the multiple MEMS micromirror array chips share a common adapter board 39, and the multiple MEMS micromirror array chips are electrically connected to the adapter board 39.

[0118] The MEMS micromirror array module provided by this invention integrates the MEMS micromirror array chip with other functional chips, uses the adapter board 39 for 2.5D flip-chip packaging, and further integrates it into an ASIC chip, etc., so that the MEMS micromirror array module can achieve high-precision real-time angle detection and feedback control with small size and low power consumption, and the performance is greatly improved. At the same time, it improves the convenience of using the overall module structure for detecting scanning angles and the flexibility of space design.

[0119] Specifically, after the MEMS micromirror array module is packaged, a high-precision photoelectric angle position detector can be used to calibrate the capacitive angle sensing structure integrated with the MEMS micromirror monolith within the MEMS micromirror array module. This calibrates the monotonic function relationship between the capacitance difference value of the capacitive angle sensing structure and the scanning angle. In actual use, the MEMS micromirror array module can directly use the capacitive angle sensing structure to detect the scanning angle of the MEMS micromirror, eliminating the need for a photoelectric angle position detector. This avoids the need for continuous online angle detection using a photoelectric angle position detector, as is common in traditional photoelectric scanning equipment. It also significantly reduces the manpower and resources required for calibrating the MEMS micromirror array module with two-dimensional meshing, large data volume, and high-precision scanning drive characteristics before use, thereby substantially reducing production and usage costs.

[0120] In one embodiment, a light window is provided on the side of the MEMS micromirror array module near the MEMS micromirror structure 10 to protect the MEMS micromirror array chip. An antireflection coating is deposited on the light window to improve the light utilization rate of the micromirror structure 10, thereby reducing light loss during light transmission in the micromirror array module.

[0121] In one embodiment, a heat dissipation structure is provided on the side of the MEMS micromirror array module away from the MEMS micromirror structure 10 after packaging, so as to enhance the heat dissipation of the module and ensure the stable operation of the module.

[0122] Example 4:

[0123] This embodiment provides an optical scanning device, which includes any of the MEMS micromirror array modules described in Embodiment 3. The optical scanning device also includes a control system, which is connected to the MEMS micromirror array module to input preset scanning angle position information or angle-time function curves to the MEMS micromirror array module.

[0124] In this embodiment, the optical scanning device is a FlexRay device in a high-end lithography machine. The FlexRay device further includes an energy equalization component, a beam splitting component, a failed micromirror shielding component, a Fourier transform lens group, and a pupil surface. The energy equalization component, the beam splitting component, the failed micromirror shielding component, the MEMS micromirror array module, the Fourier transform lens group, and the pupil surface are arranged sequentially along the optical path propagation direction. The control system controls the deflection angle of the biaxial micromirror surface 11 of the MEMS micromirror array module to obtain a preset pupil distribution pattern on the pupil surface, so as to achieve the best matching between the pupil pattern and the lithography mask, thereby realizing the lithography resolution enhancement function based on "light source-mask joint optimization (SMO)".

[0125] Currently, in the field of optical scanning, it is generally believed that only photoelectric angle position detectors can meet the high-precision angle detection requirements of optical technology. On the other hand, the process of monolithically integrating angle detection sensors in micromirror array chips is complex, the angle detection accuracy is not high, and the required lead and wiring density will increase exponentially. Achieving such a structure and effect is technically very difficult in the design, manufacturing, packaging, and testing of MEMS micromirror array chips. Therefore, in existing technologies, in optical scanning devices such as free pupil generators that require optical scanning accuracy on the order of 10 μrad, a photoelectric angle position detector is generally used as an additional configuration to achieve online detection of micromirror scanning accuracy. The basic principle of the photoelectric angle position detector is to use a collimated laser beam incident on the micromirror surface of the MEMS micromirror under test. After being reflected by the micromirror surface, the collimated laser beam enters the photoelectric sensor to obtain the two-dimensional coordinates of the centroid of the reflected light spot, and the two-dimensional scanning angle position of the MEMS micromirror is obtained by calculation. Because photoelectric angular position detectors cannot simultaneously obtain the two-dimensional coordinates of the centroids of all micromirrors, they need to be detected one by one in a time-division manner. This results in low bandwidth of the output angular position signal data, which cannot meet the bandwidth requirements for real-time monitoring and feedback control of MEMS micromirror array chips. Currently, the "micromirror photoelectric angular position detector" based on the photoelectric displacement sensor (PSD) in the free pupil generation device of the high-end DUV lithography machine designed by industry leader ASML uses the PSD to receive the light spot reflected after collimating laser light is grazing into the micromirror to measure the angular position of the micromirror. It can only detect one light spot at a time, and still needs to detect the angles of each biaxial micromirror surface 11 in the micromirror array in turn. Therefore, the detection cycle is still long and cannot meet the requirements of real-time monitoring and feedback control. Asynchronous angle detection is still affected by environmental factors, which affects the accuracy of angle detection. In addition, each micromirror requires a separate collimating laser beam, and the micromirror array requires the collimating beam of the array, which is very costly. Before using a MEMS micromirror array module, each dual-axis scanning micromirror needs to undergo individual, high-precision, two-dimensional gridded calibration testing. This testing workload is enormous, and the cost is also very high. Micromirror photoelectric angle position detectors are inconvenient to use, interfere with the main optical path, occupy a large space, and have less than ideal angle detection efficiency. Furthermore, PSD-based photoelectric angle position detectors suffer from crosstalk between scanning angles in two scanning directions due to electronic noise, making high-precision detection difficult.

[0126] This invention applies a micromirror array module, which integrates capacitive angle sensing with a micromirror monolithic chip, to a free-pupil generation device. Through ingenious structural and wiring sharing, it achieves high-density wiring of the capacitive angle sensing structure monolithically integrated into a large-scale, high-density micromirror array chip. This meets the real-time, high-bandwidth, and high-precision scanning angle detection requirements of free-pupil generation devices in high-end lithography machines (such as lithography machines with processes of 28 nm or less, including 28nm, 14nm, and 7nm processes) for MEMS micromirror arrays. Simultaneously, it eliminates the need for an external photoelectric angle position detector, utilizing the micromirror array chip's own structure to achieve independent, synchronous, real-time, high-bandwidth scanning angles of each biaxial micromirror surface 11 within the micromirror array. This detection method achieves higher scanning angle detection accuracy and signal bandwidth than existing technologies, greatly improving the measurement efficiency of micromirror scanning angles in free pupil generation devices. Most importantly, it creates conditions for high-precision, real-time feedback control of scanning angles in MEMS micromirror arrays. It overcomes the technical bias of existing technologies regarding the complexity and accuracy limitations of integrated angle detection sensors in micromirror arrays, breaks through the design concept of micromirror angle detection in optical scanning equipment with high-precision optical scanning requirements such as free pupil generation devices, simplifies the structural design of micromirror array angle detection, reduces the cost of devices for angle detection of micromirror arrays in modified equipment, and increases the design freedom of free pupil generation devices. This represents a significant advancement in existing technology.

[0127] Specifically, when the control system inputs preset scanning angle position information to the MEMS micromirror array module, it is a static angle position control; when the control system inputs an angle-time function curve to the MEMS micromirror array module, it is a quasi-static angle position control, which can be selected according to the specific application scenario.

[0128] Example 5:

[0129] This embodiment provides an optical scanning device, which is similar in other features to the optical scanning device in Embodiment 4, except that:

[0130] like Figure 9As shown, the optical scanning device in this embodiment is an all-optical switching matrix in an optical communication system. The all-optical switching matrix includes two MEMS micromirror array modules: a first micromirror array module 411 and a second micromirror array module 412. The all-optical switching matrix also includes an input fiber collimator array 421 and an output fiber collimator array 422. The input fiber collimator array 421 is aligned with the first micromirror array module 411 to emit an input collimated beam 451 to the first micromirror array module 411. The output fiber collimator array 422 is aligned with the second micromirror array module 412. The micromirror array module 412 is aligned to receive the output collimated beam 452 reflected from the second micromirror array module 412; the first micromirror array module 411 transmits the exchange collimated beam 453 to the second micromirror array module 412; the control system controls the two-dimensional deflection angle of the biaxial micromirror surfaces 11 of the first micromirror array module 411 and the second micromirror array module 412 to minimize the optical insertion loss between the input fiber collimator array 421 and the output fiber collimator array 422, with the fiber-to-fiber insertion loss being 1.5-3dB.

[0131] Specifically, the above insertion loss range is for illustrative purposes only, and the actual range should be based on the lowest optical insertion loss obtained.

[0132] In existing technologies, with the explosive growth in computing power demand from AI technology, achieving ultra-high bandwidth all-optical switching matrices (OXCs), as the core equipment for fiber optic routing and switching, has become the mainstream trend in technological development. The requirements for the micromirror scanning angle accuracy of OXCs have reached the order of 10μrad. In previous OXCs, the scanning angle of the micromirror array was adjusted using a photodetector based on fiber power detection. However, since there are two micromirror array chips in the OXC that switch optical paths, it is difficult to determine the specific angle value that each micromirror array chip needs to be adjusted. At the same time, the adjustment speed is slow, the accuracy is poor, and it also increases the insertion loss of the OXC, as well as occupying a large volume and high cost. Currently, Google's industry-leading OXC device uses a "micromirror photoelectric angular position detector" based on a CCD / CMOS image sensor to monitor the angular position information of the micromirror array. Because it requires two monitoring channels to monitor the angular position information of the two micromirror array chips respectively, and each monitoring channel also needs to be equipped with an 850nm semiconductor laser array, the size, power consumption and cost of the OXC are significantly increased. In addition, the collimated laser beam used for detection will also have optical interference effects on the communication beam being exchanged. At the same time, the device still essentially uses the reflected light spot of the micromirror for photoelectric detection. Its light spot image data output is limited by the frame rate, and only one light spot can be detected at the same time. It can only detect each micromirror surface in the micromirror array in turn, resulting in a long detection cycle and still failing to achieve real-time monitoring and feedback control.

[0133] This invention applies a micromirror array module, which integrates capacitive angle sensing detection with a micromirror array on a single chip, to OXC. This achieves high-density wiring of a monolithically integrated capacitive angle sensing structure within a high-density micromirror array chip, thus meeting the high-density arrangement, high-bandwidth, and high-precision scanning angle detection requirements of OXC for MEMS micromirror arrays. It eliminates the need for an additional structure for photoelectric angle position detectors, resulting in a small size, low power consumption, and low cost. Simultaneously, it can perform real-time, high-bandwidth, synchronous scanning angle detection of the micromirror array, significantly shortening the detection cycle and improving the angle detection accuracy and efficiency of OXC. This enables real-time feedback control of the scanning angle, resulting in lower optical insertion loss, faster switching speed, and better environmental stability, overcoming a performance bottleneck that has long been difficult to solve in OXC devices.

[0134] In one embodiment, such as Figure 9 As shown, the all-optical switching matrix further includes an input single-mode fiber array 431 and an output single-mode fiber array 432. The input single-mode fiber array 431 transmits the light beam to the first micromirror array module 411 through the input fiber collimator array 421; the output single-mode fiber array 432 receives the light beam reflected from the second micromirror array module 412 through the output fiber collimator array 422.

[0135] In one embodiment, such as Figure 9 As shown, the all-optical switching matrix further includes a first FPC stripline 441 and a second FPC stripline 442; the first FPC stripline 441 is connected to the connector 36 in the first micromirror array module 411 to enable signal transmission between the control system of the all-optical switching matrix and the first micromirror array module 411; the second FPC stripline 442 is connected to the connector 36 in the second micromirror array module 412 to enable signal transmission between the control system of the all-optical switching matrix and the second micromirror array module 412.

[0136] In one embodiment, the all-optical switching matrix further includes fiber optic patch cords, which can replace faulty micromirrors by deflecting the light beams emitted by the input single-mode fiber array 431 or the output single-mode fiber array 432 to align with normally functioning micromirrors near the faulty micromirror when some micromirrors in the MEMS micromirror array module fail, thereby achieving a highly fault-tolerant all-optical switching matrix.

[0137] In one embodiment, each input single-mode fiber array 431 includes 100 input fibers, each output single-mode fiber array 432 includes 100 output fibers, the input fiber collimator array 421 and the output fiber collimator array 422 each include 11 rows and 11 columns of fiber collimator units, and each MEMS micromirror array module includes 11 rows and 11 columns of MEMS micromirror array chips. This all-optical switching matrix can achieve a fiber optic line switching time of less than or equal to 10 milliseconds, an end-to-end optical insertion loss of less than or equal to 2.0 dB, and a redundancy of up to 21% for the MEMS micromirror array chips. Even when 21 micromirror array chips in each MEMS micromirror array module fail, the all-optical switching matrix can still operate normally.

[0138] In one embodiment, each MEMS micromirror array chip is 14 mm long and 14 mm wide, the center-to-center spacing of adjacent micromirror structures 10 is 1.2 mm, and the diameter of each biaxial micromirror mirror 11 is 0.75 mm.

[0139] In one embodiment, the micromirror structure 10 in the MEMS micromirror array chip is made of SOI (silicon-on-insulator) material. The biaxial micromirror surface 11 in the micromirror structure 10 includes a single crystal silicon with a thickness of 30 micrometers and a titanium / gold thin film with a thickness of 200 nanometers deposited on the surface. The biaxial micromirror surface 11 has a light reflectivity of greater than or equal to 98% in the 1550 nanometer band of optical communication.

[0140] In one embodiment, such as Figure 9 As shown, all devices of the all-optical switching matrix are fixedly mounted on the optical platform panel 46, which is made of aluminum alloy and has a grid of positioning holes for optical adjustment.

[0141] Specifically, after optically assembling and adjusting each device in the all-optical switching matrix, a calibration test is performed. The scanning angle data of each micromirror structure 10 in the first micromirror array module 411 and the second micromirror array module 412 is recorded when the insertion loss is minimized in any one-to-one switching mode. This data serves as the control parameter for the all-optical switching matrix during operation. This calibration test only requires monitoring equipment such as a 1550nm light source and is automatically completed under the control of the all-optical switching matrix's control system. It eliminates the need for a photoelectric angle position detector, significantly reducing calibration time, complexity, and efficiency—features unattainable by existing all-optical switching matrices.

[0142] Example 6:

[0143] This embodiment provides an optical scanning device, which is similar in other features to the optical scanning device in Embodiment 4, except that:

[0144] The optical scanning device is a vector optical phased array (VOPA), which further includes an optical beam splitter and an optical phase shifter. The optical phase shifter performs optical phase shifting on multiple beams obtained after passing through the optical beam splitter. The MEMS micromirror array module deflects the multiple beams after optical phase shifting at different angles. The optical phase shifter and the MEMS micromirror array module work together to adjust the light emitted from the optical beam splitter so that the light beams are coherently superimposed in the far field and scanned to the target angle.

[0145] Currently, vector optical phased arrays (PSAs) for space laser communication are under research. Because they are suitable for ultra-long-distance, multi-beam coherent superposition beam scanning, they require higher precision in optical scanning. Current angle detectors for micromirror arrays on the market often cannot achieve synchronous, real-time angle detection, resulting in low detection efficiency, large size, and inflexible use, making them unsuitable for the precision requirements of vector optical phased arrays. This invention integrates a capacitive angle sensing module and a micromirror array into a vector optical phased array, achieving real-time, synchronous, high-bandwidth, and high-precision scanning angle detection. This, combined with an optical phase shifter, enables long-distance coherent laser superposition to obtain single-beam or multi-beam vector directional scanning, meeting the scanning angle detection requirements of vector optical phased arrays.

[0146] In summary, the MEMS micromirror array chip, module, and optical scanning device of this invention achieve real-time, high-bandwidth, and high-precision scanning angle detection and feedback control at the array level by incorporating a micromirror array chip monolithically integrated with a capacitive sensor. This improves the accuracy and speed of micromirror array scanning angle detection, as well as the scanning speed of the micromirror array, and enhances the anti-interference capability of micromirror array angle detection against environmental factors such as vibration and temperature changes. Simultaneously, the use of frequency division multiplexing to isolate the sensing signal and driving signal reduces the wiring density requirements for micromirror array angle detection. Furthermore, the use of a thick substrate with through-silicon vias satisfies high-density wiring, enabling the application of micromirror arrays with integrated capacitive angle sensing structures in large-array, high-density micromirror scanning devices. Finally, by applying the micromirror array monolithically integrated with the capacitive sensor to free pupil generation devices, all-optical switching matrices, and vector optical phased arrays, the need for photoelectric angle detectors used in these fields is eliminated. This allows for simultaneous real-time scanning angle detection and feedback of all micromirror structures within the micromirror array, improving the speed and accuracy of scanning angle detection and feedback control in these devices, while reducing device size, increasing the efficiency of accuracy calibration and adjustment, and lowering device costs.

[0147] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0148] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A MEMS micromirror array chip, characterized in that, The MEMS micromirror array chip includes: multiple micromirror structures arranged in an array, a substrate, and a vertical lead structure; Each of the micromirror structures includes a biaxial micromirror surface and an electrostatic drive structure. The biaxial micromirror surface is deflectable by the electrostatic drive structure. The electrostatic drive structure includes an inner axis driving high and low comb tooth group for driving the biaxial micromirror surface to deflect about a symmetry axis parallel to a first direction, and an outer axis driving high and low comb tooth group for driving the biaxial micromirror surface to deflect about a symmetry axis parallel to a second direction. The first direction and the second direction are perpendicular and parallel to the biaxial micromirror surface. The inner axis driving high and low comb tooth group constitutes a set of capacitive angle sensing structures, and the outer axis driving high and low comb tooth group constitutes another set of capacitive angle sensing structures. The substrate includes an upper surface and a lower surface disposed opposite to each other. The vertical lead structure penetrates the upper surface and the lower surface of the substrate. The vertical lead structure is electrically connected to the inner axis driving high and low comb tooth group and the outer axis driving high and low comb tooth group, respectively, and the electrical connection is led out to the lower surface of the substrate.

2. A MEMS micromirror array chip, characterized in that, The MEMS micromirror array chip includes: multiple micromirror structures arranged in an array, a capacitor plate, a substrate, and a vertical lead structure. Each of the micromirror structures includes a biaxial micromirror surface and an electrostatic drive structure. The biaxial micromirror surface is deflectable by the electrostatic drive structure. The substrate includes an upper surface and a lower surface that are disposed opposite to each other. The capacitor plate is located on the upper surface of the substrate at a position parallel to and corresponding to the biaxial micromirror surface. The capacitor plate and the biaxial micromirror surface constitute a capacitance angle sensing structure. The vertical lead structure passes through the upper and lower surfaces of the substrate. The vertical lead structure is electrically connected to the biaxial micromirror surface, the capacitor plate, and the electrostatic drive structure, and the electrical connection is led out to the lower surface of the substrate. The biaxial micromirror surface is grounded through the vertical lead structure.

3. The MEMS micromirror array chip according to claim 1 or 2, characterized in that, The substrate is made of silicon and has through-silicon vias. The through-silicon vias contain conductive low-resistivity silicon or metal, which constitute the vertical lead structure. The thickness of the substrate is 350 micrometers to 500 micrometers.

4. A MEMS micromirror array module, characterized in that, The MEMS micromirror array module includes the MEMS micromirror array chip according to any one of claims 1-3, and further includes: a capacitance sensing detection circuit chip, a driving chip, and a precision power supply chip; the electrical connection of the vertical lead structure leading out to the lower surface of the substrate is electrically connected to the capacitance sensing detection circuit chip and the driving chip, and the precision power supply chip is electrically connected to the capacitance sensing detection circuit chip and the driving chip; the capacitance sensing detection circuit chip is used to input a sensing excitation signal to the capacitance angle sensing structure to measure the sensing capacitance value signal of the capacitance angle sensing structure and process the sensing capacitance value signal into current angle position information and output the current angle position information; the driving chip is used to transmit an angle scanning driving signal to the electrostatic driving structure; and the precision power supply chip is used to provide power to the capacitance sensing detection circuit chip and the driving chip.

5. The MEMS micromirror array module according to claim 4, characterized in that, When both the electrostatic drive structure and the capacitive angle sensing structure are driven by an inner shaft for high and low comb teeth and an outer shaft for high and low comb teeth, the sensing excitation signal input from the capacitive angle sensing detection circuit chip to the capacitive angle sensing structure and the angle scanning drive signal input from the drive chip to the electrostatic drive structure are isolated by frequency division multiplexing. The frequency of the sensing excitation signal is 100-1000 times that of the angle scanning drive signal.

6. The MEMS micromirror array module according to claim 4, characterized in that, The MEMS micromirror array module also includes a control chip, an interface chip, and connectors; The connector includes an input signal channel and an output signal channel. The interface chip is electrically connected to the connector, and the control chip is electrically connected to the interface chip. The control chip is connected to the capacitive angle sensing detection circuit chip to receive the current angle position information output by the capacitive angle sensing structure and perform feedback control. The connector is connected to the control system of an external device, and the control system outputs preset scanning angle position information to the control chip. The control chip combines the preset scanning angle position information output by the control system and the current angle position information output by the capacitive angle sensing detection circuit chip, and obtains a drive control signal according to the feedback control algorithm. The control chip distributes the drive control signal to the drive chip of each micromirror structure so that the drive chip outputs the corresponding angle scanning drive signal to drive each micromirror structure, thereby performing feedback control of the scanning angle position.

7. An optical scanning device, characterized in that, The optical scanning device includes a MEMS micromirror array module as described in any one of claims 4-6, and the optical scanning device further includes a control system, which is connected to the MEMS micromirror array module to input preset scanning angle position information or angle-time function curve to the MEMS micromirror array module.

8. The optical scanning device according to claim 7, characterized in that, The optical scanning equipment is a free pupil generation device for a lithography machine. The free pupil generation device further includes an energy equalization component, a beam splitting component, a failed micromirror shielding component, a Fourier transform lens group, and a pupil surface. The energy equalization component, the beam splitting component, the failed micromirror shielding component, the MEMS micromirror array module, the Fourier transform lens group, and the pupil surface are arranged sequentially along the optical path propagation direction. The control system controls the deflection angle of the biaxial micromirror surface of the MEMS micromirror array module to obtain a preset pupil distribution pattern on the pupil surface.

9. The optical scanning device according to claim 7, characterized in that, The optical scanning device is an all-optical switching matrix in an optical communication system. The all-optical switching matrix includes two MEMS micromirror array modules, namely a first micromirror array module and a second micromirror array module. The all-optical switching matrix also includes an input fiber collimator array and an output fiber collimator array. The input fiber collimator array is aligned with the first micromirror array module to emit an input collimated beam to the first micromirror array module. The output fiber collimator array is aligned with the second micromirror array module to receive the output collimated beam reflected from the second micromirror array module; The first micromirror array module transmits an exchange-collimated beam to the second micromirror array module; the control system controls the deflection angle of the biaxial micromirror surfaces of the first and second micromirror array modules to minimize the optical insertion loss between the input fiber collimator array and the output fiber collimator array.

10. The optical scanning device according to claim 7, characterized in that, The optical scanning device is a vector optical phased array, which further includes an optical beam splitter and an optical phase shifter. The optical phase shifter performs optical phase shifting on multiple beams obtained after passing through the optical beam splitter. The MEMS micromirror array module deflects the multiple beams after optical phase shifting at different angles. The optical phase shifter and the MEMS micromirror array module work together to adjust the light emitted from the optical beam splitter so that the light beams are coherently superimposed in the far field and scanned to the target angle.

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