A two-dimensional micromechanical bidirectional torsion mirror array and its manufacturing method

Abstract

The invention relates to a two-dimensional micromechanical bidirectional twist mirror array and a manufacturing method thereof. The two-dimensional micromechanical bidirectional twist mirror array comprises an electrode substrate and a micromirror unit arranged on the electrode substrate. The micromirror unit comprises a micromirror support structure layer, a through-hole electrode substrate and a mirror structure layer. The micromirror support structure layer comprises an anchor point, a twist beam, a first lower electrode and a second lower electrode. The through-hole electrode substrate comprises a first through-hole electrode, a second through-hole electrode and a third through-hole electrode. The first through-hole electrode is in contact with the first lower electrode, the second through-hole electrode is in contact with the second lower electrode, and the third through-hole electrode is in contact with the anchor point. The mirror structure layer comprises a mirror and a mirror support structure. The twist beam is supported by anchor points at both ends and suspended above the through-hole electrode substrate. The first lower electrode and the second lower electrode are symmetrically distributed about the twist beam. The optical field matching of the micromirror array in a spectral imaging system is improved, the system optical path is simplified, and the miniaturization of the spectral imaging system is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-opto-mechanical-mechanical systems, and in particular to a two-dimensional micro-mechanical bidirectional twisting mirror array and a manufacturing method thereof. Background Art

[0002] In recent years, spatial light modulation chips processed by microelectromechanical systems (MEMS) technology have the advantages of small size, low power consumption and cost, strong integration and customization capabilities, and have been widely used in many fields such as optical communication, projection display, medical imaging and biotechnology. Among them, the high frame rate, high resolution, programmable digital micromirror devices (DMD) designed and produced by TI (Texas Instruments) in the United States is the most representative spatial light modulator in optical MEMS at present, and has been applied in many fields such as projection equipment, microscopic imaging, and spectral imaging. The DMD structure (US patent 4615595 (1986.10.7)) consists of many small aluminum reflectors, complementary metal oxide semiconductor (CMOS) static memory, addressing electrodes, bias electrodes, yokes, hinges, etc. The micromirror array is manufactured using CMOS technology and integrated on the CMOS memory. Under the control of the digital drive signal, the torsion angle can be quickly changed, thereby changing the emission direction of the incident light. The rotation of the micromirror is accomplished by the electrostatic attraction generated by the voltage difference between the micromirror itself and the memory cell below. When the memory cell is in the "on" or "1" state, the micromirror rotates to +10°; when the memory cell is in the "off" or "0" state, the micromirror rotates to -10°.

[0003] Currently, commercial DMDs are mainly divided into two types of arrays: "diamond" and "orthogonal". In the new spectral imaging system (Optics Express, 2019, 27(12): 16995), the core device DMD is twisted by column to achieve the discrete dynamic framing of the two-dimensional target image. In combination with the traditional transmission grating, the spectral overlap phenomenon during grating filtering is eliminated, effectively improving the spectral resolution of the system. However, due to the inherent structure of the DMD and its movement mode, the DMDs of both array types have the problems of poor optical path matching and distortion of target optical information collection. When the "diamond" arranged DMD is twisted by column, the gap between the micromirror units in the same column is large, and the same column cannot be completely filled, resulting in part of the incident light not being reflected into the back-end dispersion system, resulting in distortion of the target optical information collection, limiting the improvement of the spectral imaging system's ability to finely identify the target spectrum. When the "orthogonal" DMD is twisted in columns, the incident and outgoing light rays cannot be in the same horizontal plane due to the way the micromirror units are twisted around their diagonals. Therefore, at least one optical path in the spectral imaging system needs to be fixed with the help of a special fixture, which increases the volume of the entire spectral imaging system and seriously hinders the miniaturization of the spectral imaging system. In addition, there is interference and occlusion of light between adjacent micromirror units in the same twisted column, which leads to the loss of target optical information. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a two-dimensional micromechanical bidirectional torsion mirror array and a manufacturing method thereof, which can improve the light field matching of the micromirror array in the spectral imaging system, simplify the optical path of the spectral imaging system, promote the miniaturization of the spectral imaging system, and improve the utilization rate of the target optical information.

[0005] A technical solution adopted by the present invention is a two-dimensional micromechanical bidirectional torsion mirror array, comprising an electrode substrate and N×N groups of equally spaced micromirror units arranged on the electrode substrate, wherein the micromirror units include a micromirror torsion support structure layer, a through-hole electrode substrate located below the micromirror torsion support structure layer, and a mirror structure layer located above the micromirror torsion support structure layer, wherein the micromirror torsion support structure layer includes an anchor point, a torsion beam, a first lower electrode, and a second lower electrode, wherein the torsion beam is suspended above the through-hole electrode substrate through anchor point supports at both ends, and the first lower electrode and the second lower electrode are symmetrically distributed about the torsion beam; wherein the through-hole electrode substrate includes a first through-hole electrode, a second through-hole electrode, and a third through-hole electrode arranged on the through-hole electrode substrate, wherein the first through-hole electrode is in contact with the first lower electrode, the second through-hole electrode is in contact with the second lower electrode, and the third through-hole electrode is in contact with the anchor point, wherein the mirror structure layer includes a mirror and a mirror support structure, and wherein the mirror is connected to the torsion beam through the mirror support structure.

[0006] The beneficial effects of the present invention are as follows: the two-dimensional micromechanical bidirectional twist mirror array of the above structure is adopted, and the micromirror unit is twisted around the long axis of the mirror surface by adopting the axisymmetric micromirror structure design. When the micromirror array is placed horizontally, the incident light path and the outgoing light path are located in the same horizontal plane, which improves the light field matching of the micromirror array in the spectral imaging system, and does not need to add redundant mechanical structures for the tilt of the incident or outgoing light path, thereby simplifying the system optical path and promoting the miniaturization of the spectral imaging system. The change in the mirror twisting mode eliminates the optical interference and occlusion between adjacent micromirror units in the same twisted column, and more effective target optical information can enter the back-end dispersion system, greatly improving the ability of the spectral imaging system to finely identify the spectrum.

[0007] Preferably, the torsion beam includes a central portion, the mirror support structure is connected to the central portion of the torsion beam, the mirror support structure and the mirror are an integrally formed structure, the torsion beam is symmetrical about the central portion, the number of the anchor points is two, which are respectively fitted and connected to the two ends of the torsion beam. With this structure, the mirror of each group of micromirror units is divided into two parts by the mirror support structure along the central axis of the torsion beam, that is, the micromirror structure is an axisymmetric design, which realizes the twisting of the micromirror unit around the long axis of the mirror, improves the light field matching of the micromirror array in the spectral imaging system, simplifies the system optical path, and promotes the miniaturization of the spectral imaging system.

[0008] Preferably, the micromirror unit also includes an insulating layer covering the upper surfaces of the first lower electrode and the second lower electrode. With this structure, an insulating layer is adhered to the upper surfaces of the first lower electrode and the second lower electrode, which can prevent the mirror from contacting the first lower electrode or the second lower electrode when deflected, thereby avoiding a short circuit between the mirror and the first lower electrode or the second lower electrode.

[0009] Preferably, the micromirror unit further comprises a metal reflection layer covering the upper surface of the mirror surface. With this structure, the reflection efficiency of the mirror surface can be improved.

[0010] Preferably, the first through-hole electrode, the second through-hole electrode and the third through-hole electrode all include a through-hole, a filling metal filled in the through-hole and a surface electrode covering the filling metal. With this structure, the electric potential is conducted from the electrode base to the mirror surface through the through-hole electrode, and the structure is simple.

[0011] Another technical solution adopted by the present invention is a method for manufacturing a two-dimensional micromechanical bidirectional torsion mirror array, the method comprising the following steps:

[0012] S1. Fabricating an electrode substrate using a three-dimensional integrated manufacturing process;

[0013] S2, using a MEMS etching process to make a through hole on the through hole electrode substrate;

[0014] S3, aligning and bonding the electrode substrate and the through-hole electrode substrate using a MEMS bonding process;

[0015] S4, using a metal material deposition process to complete the deposition of the filling metal in the through hole;

[0016] S5, depositing a surface electrode material on the through-hole electrode substrate by using a MEMS deposition process, and obtaining a surface electrode by a metal material patterning process;

[0017] S6, etching a first lower electrode, an anchor point, and a second lower electrode on one side of the micromirror torsion support structure layer using a MEMS etching process;

[0018] S7, performing wafer-level integration of the through-hole electrode substrate obtained in step S5 and the micromirror torsion support structure layer obtained in step S6 by using a MEMS bonding process;

[0019] S8, thinning the micromirror torsion support structure layer to a desired thickness using a MEMS thinning process, and completing the structural release of the first lower electrode and the second lower electrode;

[0020] S9, depositing an insulating material on the surfaces of the first lower electrode and the second lower electrode after the structure release is completed, and patterning the insulating material to obtain an insulating layer;

[0021] S10, etching a mirror support structure on one side of the mirror using a MEMS etching process according to the micromirror torsion angle requirement;

[0022] S11, according to the requirements of driving voltage and torsion angle, a torsion beam is etched on one side of the micromirror torsion structure layer by using a MEMS etching process;

[0023] S12, bonding the torsion beam and the mirror torsion support structure by using a MEMS process;

[0024] S13, using MEMS thinning process to complete the release of the torsion beam structure;

[0025] S14, bonding the two ends of the torsion beam to the corresponding anchor points respectively by using a MEMS process;

[0026] S15, thinning the mirror surface to a required thickness according to the micromirror driving requirements;

[0027] S16, depositing metal material on the surface of the thinned mirror and patterning it to obtain a metal reflective layer, using the metal reflective layer as a mask, and using a MEMS etching process to complete the structural release of the mirror.

[0028] By adopting the above-mentioned method for manufacturing the two-dimensional micromechanical bidirectional torsion mirror array, the MEMS technology and advanced three-dimensional packaging technology are innovatively heterogeneously integrated, which simplifies the micromirror array processing process and further improves the integration of the micromirror array chip. The manufactured micromirror array has good light field matching, simple structure, and can greatly improve the ability of the spectral imaging system to finely identify spectra. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A structural diagram of a two-dimensional micromechanical bidirectional torsion mirror array of the present invention;

[0030] Figure 2 An exploded view of a micromirror unit in the present invention;

[0031] Figure 3 A schematic diagram of the working principle of a two-dimensional micromechanical bidirectional torsion mirror array of the present invention;

[0032] Figure 4 to Figure 7 This is a schematic diagram of a two-dimensional micromechanical bidirectional twist mirror array manufacturing process in Example 1 of the present invention;

[0033] Figure 8 to Figure 11 Schematic diagram of the preparation process of a two-dimensional micromechanical bidirectional torsion mirror array in Example 2 of the present invention;

[0034] As shown in the figure: 1. electrode base; 2. first through-hole electrode; 3. second through-hole electrode; 4. third through-hole electrode; 5. first lower electrode; 6. anchor point; 7. second lower electrode; 8. torsion beam; 9. insulating layer; 10. mirror support structure; 11. mirror; 12. metal reflection layer; 13. through-hole electrode base; 14. micromirror torsion support structure layer; 14.1. first device layer; 14.2. first oxide layer; 14.3. first substrate layer; 15. Mirror structure layer; 15.1. Second device layer; 15.2. Second oxide layer; 15.3. Second substrate layer; 16. Micromirror twisting structure layer; 16.1. Third device layer; 16.2. Third oxide layer; 16.3. Third substrate layer; 17. Mirror counterclockwise twisting driving voltage source; 18. Mirror clockwise twisting driving voltage source; 19. Center; 20. End; 21. Through hole; 22. Filling metal; 23. Surface electrode. DETAILED DESCRIPTION

[0035] The invention will be further described below with reference to the accompanying drawings and in combination with specific implementations, so that those skilled in the art can implement the invention with reference to the description. The protection scope of the invention is not limited to the specific implementations.

[0036] Those skilled in the art should understand that, in the disclosure of the present invention, the orientation or positional relationship indicated by terms such as "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0037] In view of the problems existing in the prior art, such as poor light field matching of micromirror arrays in spectral imaging systems, loss of target optical information collection caused by inherent twisting mode and array form, the present invention proposes a novel two-dimensional micromechanical bidirectional twisting mirror array and its processing method, which aims to achieve twisting of micromirror units around the long axis of the mirror surface by adopting an axisymmetric micromirror structure design, thereby improving the light field matching of the micromirror array in the spectral imaging system, simplifying the system optical path, and promoting the miniaturization of the spectral imaging system. At the same time, the optical interference and occlusion between adjacent micromirror units in the same twisted column are eliminated, and the utilization rate of the target optical information is improved.

[0038] The present invention relates to a two-dimensional micro-mechanical bidirectional torsion mirror array, such as Figure 1 As shown, it includes an electrode substrate 1 and N×N groups of equally spaced micromirror units arranged on the electrode substrate 1, wherein the micromirror unit includes a micromirror torsion support structure layer 14, a through-hole electrode substrate 13 located below the micromirror torsion support structure layer 14, and a mirror structure layer 15 located above the micromirror torsion support structure layer 14, wherein the micromirror torsion support structure layer 14 includes an anchor point 6, a torsion beam 8, a first lower electrode 5, and a second lower electrode 7, wherein the torsion beam 8 is suspended above the through-hole electrode substrate 13 by supporting the anchor points 6 at both ends. The first lower electrode 5 and the second lower electrode 7 are symmetrically distributed about the torsion beam 8; the through-hole electrode substrate 13 includes a first through-hole electrode 2, a second through-hole electrode 3 and a third through-hole electrode 4 arranged on the through-hole electrode substrate 13, the first through-hole electrode 2 is in contact with the first lower electrode 5, the second through-hole electrode 3 is in contact with the second lower electrode 7, the third through-hole electrode 4 is in contact with the anchor point 6, the mirror structure layer 15 includes a mirror 11 and a mirror support structure 10, and the mirror 11 is connected to the torsion beam 8 through the mirror support structure 10.

[0039] The two-dimensional micromechanical bidirectional twist mirror array of the present invention is adopted, and the micromirror unit is twisted around the long axis of the mirror surface 11 by adopting an axisymmetric micromirror structure design. When the micromirror array is placed horizontally, the incident light path and the outgoing light path are located in the same horizontal plane, which improves the light field matching of the micromirror array in the spectral imaging system, and does not need to add redundant mechanical structures for the tilt of the light path, thereby simplifying the system light path and promoting the miniaturization of the spectral imaging system. The change in the twisting mode of the mirror surface 11 eliminates the optical interference and shielding between adjacent micromirror units in the same twisted column, and more effective target optical information can enter the back-end dispersion system, greatly improving the ability of the spectral imaging system to finely identify the spectrum.

[0040] like Figure 2 As shown, the torsion beam 8 includes a central portion 19, the mirror support structure 10 is connected to the central portion 19 of the torsion beam 8, the mirror support structure 10 and the mirror 11 are an integrally formed structure, the torsion beam 8 is symmetrical about the central portion 19, the number of the anchor points 6 is two, the two anchor points 6 are symmetrical structures, and are respectively connected to the two ends 20 of the torsion beam 8 in a corresponding manner, and the mirror 11 of each group of micromirror units is divided into two parts by the mirror support structure 10 along the central axis of the torsion beam 8, that is, the micromirror structure is an axisymmetric design, which realizes the torsion of the micromirror unit around the long axis of the mirror 11, improves the light field matching of the micromirror array in the spectral imaging system, simplifies the system optical path, and promotes the miniaturization of the spectral imaging system. The change in the torsion mode of the mirror 11 eliminates the optical interference and occlusion between adjacent micromirror units in the same torsion column, and more effective target optical information can enter the back-end dispersion system, which greatly improves the ability of the spectral imaging system to finely identify the spectrum.

[0041] like Figure 2 As shown, the micromirror unit also includes an insulating layer 9 covering the upper surfaces of the first lower electrode 5 and the second lower electrode 7. With this structure, a layer of insulating layer 9 is adhered to the upper surfaces of the first lower electrode 5 and the second lower electrode 7. This can prevent the torsion beam 8 from contacting the first lower electrode 5 or the second lower electrode 7 when twisted, thereby avoiding the mirror surface 11 from being short-circuited with the first lower electrode 5 or the second lower electrode 7.

[0042] like Figure 2 As shown, the micromirror unit further includes a metal reflection layer 12 covering the upper surface of the mirror surface 11 . With this structure, the reflection efficiency of the mirror surface 11 can be improved.

[0043] The first through-hole electrode 2, the second through-hole electrode 3 and the third through-hole electrode 4 all include a through-hole 21, a filling metal 22 filled in the through-hole 21 and a surface electrode 23 covering the filling metal 22. With this structure, the electric potential is conducted from the electrode substrate 1 to the mirror surface 11 through the through-hole 21 electrode, and the structure is simple.

[0044] The electrode substrate 1 is mainly used to provide driving electrical signals for the two-dimensional micromechanical bidirectional torsion mirror array. According to different electrode preparation processes, the material of the electrode substrate 11 is not limited to silicon, glass, polyimide, green ceramic tape, FR-4, etc.

[0045] The through-hole electrode substrate 13 is suitably made of materials that can be processed by wafer-level MEMS processing technology, and is not limited to silicon wafers or glass wafers.

[0046] The first through-hole electrode 2, the second through-hole electrode 3 and the third through-hole electrode 4 mainly function to transmit the ground signal and the voltage signal on the electrode substrate 1 to the first lower electrode 5, the second lower electrode 7 and the anchor point 6 respectively. The filling metal material of the through-hole electrode can be selected from tungsten, copper and other conductive materials according to the conductive performance requirements and process capabilities; the material of the surface electrode 23 can be selected from aluminum, gold, copper and other conductive materials according to the conductive performance requirements and process capabilities.

[0047] The micromirror torsion support structure layer 14 can be selected from ordinary silicon wafers or SOI (silicon-on-insulator) silicon wafers.

[0048] The insulating layer 9 is mainly used to prevent the mirror 11 from being short-circuited with the first lower electrode 5 or the second lower electrode 7. The material for preparing the insulating layer 9 may be silicon oxide, silicon nitride, polysilicon, etc., depending on the insulation requirements.

[0049] The shape of the torsion beam 8 may be, but is not limited to, a straight beam, a serpentine beam, a trapezoidal beam, etc., depending on the micromirror driving voltage requirement.

[0050] The micromirror torsion structure layer 16 is used to manufacture the torsion beam 8, and its material can be selected from ordinary silicon wafers or SOI (silicon-on-insulator) silicon wafers.

[0051] The mirror surface 11 acts as a reflective mirror surface 11 and also serves as the upper electrode of the micromirror unit. The potential signal is emitted from the electrode substrate 1, passes through the through-hole electrode, the anchor point 6, the torsion beam 8, and the micromirror support structure to reach the mirror surface 11. The material of the mirror structure layer 15 can be selected as a silicon wafer with a high doping concentration or an SOI silicon wafer according to the conductive performance requirements and the actual processing method.

[0052] The metal reflective layer 12 is made of a suitable material, such as gold, aluminum, silver, etc., according to the operating band of the micromirror and the surface quality requirements.

[0053] The basic working principle of the present invention is: Figure 3(a), the mirror surface 11 of each group of micromirror units is divided into two parts by the mirror support structure 10 along the central axis of the torsion beam 8, and the first lower electrode 5 and the second lower electrode 7 are distributed at the positions corresponding to the two parts of each group of micromirror units on the through-hole electrode substrate 13; a micromirror counterclockwise torsion voltage source is applied between the first lower electrode 5 and the mirror surface 11, and a micromirror clockwise torsion voltage source is applied between the second lower electrode 7 and the mirror surface 11; the micromirror counterclockwise torsion voltage source and the micromirror clockwise torsion voltage source provide the driving voltage required for bidirectional torsion of each group of micromirror units.

[0054] See also Figure 3 (b), when the driving voltage is turned on, the mirror surface 11 of the i-th group of micromirror units is twisted counterclockwise around the axis of the torsion beam 8 under the action of electrostatic attraction and the restriction of the torsion beam 8, generating a torsion angle; when the driving voltage is turned on, the mirror surface 11 of the j-th group of micromirror units is twisted counterclockwise around the axis of the torsion beam 8 under the action of electrostatic attraction and the restriction of the torsion beam 8, generating a torsion angle; when the driving voltage of the i-th group of micromirror units is equal to the driving voltage of the j-th group of micromirror units, the torsion angles generated by the i-th and j-th groups of mirror surfaces 11 are equal, that is, =θ1=θ2.

[0055] See also Figure 3 (c) When the driving voltage of the i-th group of micromirror units is not equal to the driving voltage of the j-th group of micromirror units, the twist angles generated by the i-th group and the j-th group of mirrors 11 are not equal, that is, θ1≠θ2; thereby achieving more complex spatial light modulation.

[0056] See also Figure 3 (d) When the driving voltage is turned on, the mirror surface 11 of the i-th group of micromirror units is twisted clockwise around the axis of the torsion beam 8 under the action of electrostatic attraction and the restriction of the torsion beam 8, generating a torsion angle; when the driving voltage is turned on, the mirror surface 11 of the j-th group of micromirror units is twisted clockwise around the axis of the torsion beam 8 under the action of electrostatic attraction and the restriction of the torsion beam 8, generating a torsion angle; when the driving voltage of the i-th group of micromirror units is equal to the driving voltage of the j-th group of micromirror units, the torsion angles generated by the i-th and j-th groups of micromirror mirror surfaces 11 are equal, that is, θ3=θ4.

[0057] See also Figure 3 (e) When the driving voltage of the i-th group of micromirror units is not equal to the driving voltage of the j-th group of micromirror units, the twist angles generated by the i-th group and the j-th group of mirrors 11 are not equal, that is, θ3≠θ4; thereby achieving more complex spatial light modulation.

[0058] See also Figure 4 The present invention proposes a two-dimensional micro-mechanical bidirectional torsion mirror array processing method, which includes the following basic steps:

[0059] S1. See Figure 4(a) The electrode substrate 1 is manufactured using a three-dimensional integrated manufacturing process;

[0060] The three-dimensional integrated manufacturing process can be a low-temperature ceramic co-firing technology, a through-silicon via interconnection process, etc.

[0061] S2. See Figure 4 (b), using a MEMS etching process to form a through hole 21 on the through hole electrode substrate 13;

[0062] The MEMS etching process can be a wet etching process, a dry deep etching process, a surface laser processing process, etc.

[0063] S3. See Figure 4 (c) Aligning and bonding the electrode substrate 1 and the through-hole electrode substrate 13 using a MEMS bonding process;

[0064] The MEMS bonding process may be an anodic bonding process, an adhesive bonding process, a direct bonding process, etc.;

[0065] S4. See Figure 4 (d) Deposition of the filling metal 22 in the through hole 21 is completed by using a metal material deposition process;

[0066] The metal material deposition process may be an electroplating process, a chemical vapor deposition process, etc.;

[0067] S5. See Figure 4 (e) depositing the surface electrode 23 material on the through-hole electrode substrate 13 by using a MEMS deposition process, and obtaining the surface electrode 4.3 by a metal material patterning process;

[0068] The MEMS deposition process may be an electron beam evaporation process, a magnetron sputtering process, etc.;

[0069] The metal material patterning process can be a metal stripping process, a metal wet etching process, a metal dry etching process, etc.;

[0070] S6. See Figure 5 (a) A first lower electrode 5, an anchor point 6 and a second lower electrode 7 of a certain height are etched on one side of the micromirror torsion support structure layer 14 by using a MEMS etching process;

[0071] The MEMS etching process can be a wet etching process, a dry deep etching process, a surface laser processing process, etc.

[0072] S7, see Figure 5 (b) The through-hole electrode substrate 13 and the micromirror torsion support structure layer 14 processed in step 5 and step 6 are integrated at the wafer level by using a MEMS bonding process;

[0073] The MEMS bonding process can be selected from anodic bonding process, gold-silicon bonding process, adhesive bonding process, direct bonding process, etc. according to different substrate materials;

[0074] S8. See Figure 5 (c) using a MEMS thinning process to thin the micromirror torsion support structure layer 14 to a desired thickness, thereby completing the structural release of the first lower electrode 5 and the second lower electrode 7;

[0075] The MEMS thinning process can be selected from a wet etching process, a dry deep etching process, a chemical mechanical polishing process, etc.

[0076] S9. See Figure 5 (d) depositing an insulating material on the surfaces of the first lower electrode 5 and the second lower electrode 7 after the structure release and patterning to obtain an insulating layer 9;

[0077] The insulating material deposition process mainly includes low temperature chemical vapor deposition process, plasma enhanced chemical vapor deposition process, electron beam evaporation process, etc.

[0078] S10. See Figure 6 (a), according to the micromirror torsion angle requirement, a mirror support structure 10 of a certain height is etched on one side of the mirror 11 using a MEMS etching process;

[0079] The MEMS etching process is a dry deep etching process, a wet etching process, etc.

[0080] S11. See Figure 6 (b) according to the requirements of driving voltage and torsion angle, a torsion beam 8 of a certain depth is etched on one side of the micromirror torsion structure layer 16 by using a MEMS etching process;

[0081] The MEMS etching process is a dry deep etching process, a wet etching process, etc.

[0082] S12. See Figure 6 (c), bonding the torsion beam 8 and the mirror support structure 10 using a MEMS process;

[0083] The MEMS bonding process can be an anodic bonding process, an adhesive bonding process, or a direct bonding process;

[0084] S13. See Figure 6 (d) The torsion beam 8 is released by using the MEMS thinning process;

[0085] The MEMS thinning process can be selected from a wet etching process, a dry deep etching process, a chemical mechanical polishing process, etc.

[0086] S14. See Figure 7(a), bonding the two ends 20 on the torsion beam 8 and the corresponding anchor points 6 using a MEMS process;

[0087] The MEMS bonding process can be an anodic bonding process, an adhesive bonding process, or a direct bonding process;

[0088] S15. See Figure 7 (b), according to the micromirror driving requirements, the mirror surface 11 is thinned to a required thickness;

[0089] The thinning process can be selected from wet etching process, dry deep etching process, chemical mechanical polishing process, etc.

[0090] S16. See Figure 7 (c) depositing a metal material on the surface of the thinned mirror 11 and patterning it to obtain a metal reflective layer 12, using the metal reflective layer 12 as a mask and using a MEMS etching process to complete the structural release of the mirror 11;

[0091] The deposition process may be electron beam evaporation process, magnetron sputtering process, etc.

[0092] The MEMS etching process can be selected from dry deep etching process, surface laser processing process, wet etching process and the like.

[0093] Embodiment 1:

[0094] The two-dimensional micromechanical bidirectional torsion mirror array in this embodiment mainly includes an electrode substrate 1 and 10×10 groups of micromirror units placed on the electrode substrate 1, the spacing between the micromirror units is 2μm, and each group of micromirror units mainly includes a first through-hole electrode 2, a second through-hole electrode 3, a third through-hole electrode 4, a first lower electrode 5, an anchor point 6, a second lower electrode 7, a torsion beam 8, an insulating layer 9, a mirror support structure 10, a mirror 11 and a metal reflective layer 12, and the mirror 11 is a square structure of 20μm×20μm. The first through-hole electrode 2, the second through-hole electrode 3 and the third through-hole electrode 4 are prepared from a through-hole electrode substrate 13, the first lower electrode 5, the anchor point 6, the torsion beam 8 and the second lower electrode 7 together constitute a micromirror torsion support structure layer 14, and the first lower electrode 5, the anchor point 6 and the second lower electrode 7 correspond to and are in close contact with the first through-hole electrode 2, the third through-hole electrode 4 and the second through-hole electrode 3, respectively. The first lower electrode 5 and the second lower electrode 7 are symmetrically distributed about the torsion beam 8, and the insulating layer 9 is made on the surface of the first lower electrode 5 and the second lower electrode 7. The torsion beam 8 is supported by the anchor point 6 and suspended above the through-hole electrode substrate 13, and is prepared by the micromirror torsion structure layer 16. The mirror structure layer 15 includes a mirror support structure 10 and a mirror 11. The mirror support structure 10 and the mirror 11 are an integrally formed structure, and the mirror 11 is connected to the torsion beam 8 through the mirror support structure 10 below it. In order to improve the mirror reflection efficiency, a metal reflection layer 12 is covered on the mirror 11.

[0095] In the present embodiment, the material of the electrode substrate 1 is a raw porcelain tape; the through-hole electrode substrate 13 is a silicon wafer; the filling metal material of the first through-hole electrode 2, the second through-hole electrode 3 and the third through-hole electrode 4 is tungsten, and the surface electrode material is aluminum; the micromirror torsion support structure layer 14 is an ordinary silicon wafer; the shape of the torsion beam 8 is selected as a straight beam according to the micromirror driving voltage requirement, and the micromirror torsion structure layer 16 is an ordinary silicon wafer; the insulating layer 9 is silicon oxide; the mirror structure layer 15 is a silicon wafer with a high doping concentration; and the metal reflective layer 12 is prepared from gold.

[0096] See also Figure 4 The manufacturing process of the two-dimensional micromechanical bidirectional torsion mirror array proposed by the present invention comprises the following steps:

[0097] Step 1: Read Figure 4 (a) The electrode substrate 1 is manufactured by using a low temperature co-fired ceramic process;

[0098] Step 2: See Figure 4 (b) A 300 μm silicon wafer is used as the through-hole electrode substrate 13, and a through-hole 21 is made on the 300 μm silicon wafer by a dry deep etching process;

[0099] Step 3: Read Figure 4 (c) Aligning and bonding the electrode substrate 1 and the 300 μm silicon wafer using a direct bonding process;

[0100] Step 4: Read Figure 4 (d) using a chemical vapor deposition process to complete the deposition of metal tungsten filling in the through hole;

[0101] Step 5: See Figure 4 (e) A 200 nm aluminum film is deposited on a silicon wafer using an electron beam evaporation process, and then patterned by a metal lift-off process to obtain a surface electrode;

[0102] Step 6: Read Figure 5 (a) A 500 μm ordinary silicon wafer is used to make a micromirror torsion support structure layer, that is, a 15 μm first lower electrode 5, an anchor point 6 and a second lower electrode 7 are etched on one side of the 500 μm ordinary silicon wafer using a dry deep etching process;

[0103] Step 7: See Figure 5 (b) The through-hole electrode substrate 13 and the micromirror torsion support structure layer 14 processed in step 5 and step 7 are integrated at the wafer level by using a silicon-silicon direct bonding process;

[0104] Step 8: See Figure 5 (c) Using a chemical mechanical polishing process, a 500 μm ordinary silicon wafer is thinned to 15 μm to complete the structural release of the first lower electrode 5 and the second lower electrode 7;

[0105] Step 9: See Figure 5 (d) using a low-temperature chemical vapor deposition process to deposit 200 nm of silicon oxide on the surfaces of the first lower electrode 5 and the second lower electrode 7 after the structure release, and patterning them to obtain an insulating layer 9;

[0106] Step 10: See Figure 6 (a) A mirror structure layer 15 is made of a 300 μm high-doping concentration silicon wafer. According to the micromirror torsion angle requirement, a 15 μm mirror support structure 10 is prepared on the surface of the 300 μm high-doping concentration silicon wafer by a dry deep etching process;

[0107] Step 11: See Figure 6 (b) A 300 μm silicon wafer is used as the micromirror twist structure layer 16. According to the requirements of the driving voltage and the twist angle, a 10 μm deep twist beam 8 is etched on one side of the 300 μm silicon wafer using a dry deep etching process;

[0108] Step 12: See Figure 6 (c) bonding the torsion beam 8 to the mirror support structure 10 using a silicon-silicon direct bonding process;

[0109] Step 13: See Figure 6 (d) using chemical mechanical polishing to complete the release of the torsion beam 8 structure;

[0110] Step 14: See Figure 7 (a), bonding the two ends of the torsion beam 8 and the anchor point 6 using a silicon-silicon direct bonding process;

[0111] The MEMS bonding process can be an anodic bonding process, an adhesive bonding process, or a direct bonding process;

[0112] Step 15: See Figure 7 (b) According to the micromirror driving requirements, the 300μm high-doping concentration silicon wafer is thinned to 25μm using the chemical mechanical polishing process.

[0113] Step 16: See Figure 7 (c) A 200 nm gold film is deposited on the surface of the thinned mirror structure layer 15 by electron beam evaporation and patterned to obtain a metal reflective layer 12. The metal reflective layer 12 is used as a mask and a dry deep etching process is used to complete the structure release of the mirror 11.

[0114] Embodiment 2:

[0115] The two-dimensional micromechanical bidirectional torsion mirror array in this embodiment mainly includes an electrode substrate 1 and 200×200 groups of micromirror units placed on the electrode substrate 1. The spacing between the micromirror units is 1μm. Each group of micromirror units mainly includes a first through-hole electrode 2, a second through-hole electrode 3, a third through-hole electrode 4, a first lower electrode 5, an anchor point 6, a second lower electrode 7, a torsion beam 8, an insulating layer 9, a mirror support structure 10, a mirror 11 and a metal reflective layer 12. The mirror 11 is a square structure of 25μm×25μm. The first through-hole electrode 2, the second through-hole electrode 3, and the third through-hole electrode 4 are arranged on the through-hole electrode substrate 13. The first lower electrode 5, the anchor point 6, the torsion beam 8 and the second lower electrode 7 together constitute a micromirror torsion support structure layer. The first lower electrode 5, the anchor point 6 and the second lower electrode 7 correspond to and are in close contact with the first through-hole electrode 2, the third through-hole electrode 4 and the second through-hole electrode 3 respectively. The first lower electrode 5 and the second lower electrode 7 are symmetrically distributed about the torsion beam 8, and the insulating layer 9 is made on the surface of the first lower electrode 5 and the second lower electrode 7. The torsion beam 8 is supported by the anchor point 6 and suspended above the through-hole electrode substrate 13, and is made of a micromirror torsion structure layer 16. The mirror structure layer 15 includes a mirror support structure 10 and a mirror 11. The mirror support structure 10 and the mirror 11 are an integrally formed structure, and the mirror 11 is connected to the torsion beam 8 through the mirror support structure 10 below it. In order to improve the mirror reflection efficiency, a metal reflection layer 12 is covered on the mirror 11.

[0116] In this embodiment, the material of the electrode substrate 1 is silicon; the through-hole electrode substrate 13 is a BF33 glass sheet; the filling metal material of the first through-hole electrode 2, the second through-hole electrode 3 and the third through-hole electrode 4 is copper, and the surface electrode material is gold; the micromirror torsion support structure layer 14 is an SOI silicon wafer (the SOI silicon wafer 14 includes a 15μm first device layer 14.1, a 0.5μm first oxide layer 14.2 and a 300μm first substrate layer 14.3); the shape of the torsion beam 8 is selected as a folded beam according to the micromirror driving voltage requirement, and the micromirror torsion structure layer material 16 is an SOI wafer (the SOI silicon wafer 16 includes a 15μm third device layer 16.1, a 1.5μm third oxide layer 16.2 and a 350μm third substrate layer 16.3); the insulating layer 9 is silicon nitride. The mirror structure layer 15 is a SOI silicon wafer (the SOI silicon wafer 15 includes a 20 μm second device layer 15.1, a 2 μm second oxide layer 15.2 and a 400 μm second substrate layer 15.3); the material of the metal reflective layer 12 is aluminum.

[0117] See also Figure 5 The manufacturing process of the micro-mechanical electrostatically driven micro-mirror array proposed by the present invention comprises the following steps:

[0118] Step 1: Read Figure 8 (a) The electrode substrate 1 is manufactured by using a through silicon via interconnection process;

[0119] Step 2: See Figure 8 (b) A 300 μm BF33 glass sheet is used as a through-hole electrode substrate 13, and a through-hole is made on the 300 μm BF33 glass sheet using a surface laser processing process;

[0120] Step 3: Read Figure 8 (c) Aligning and bonding the electrode substrate 1 and the BF33 glass sheet 13 using a silicon-glass anodic bonding process;

[0121] Step 4: Read Figure 8 (d) using an electroplating process to complete the deposition of metal copper filling in the through hole;

[0122] Step 5: See Figure 8 (e) A 250 nm gold film is deposited on a BF33 glass sheet 13 by a magnetron sputtering process, and the gold film is patterned by a metal wet etching process to obtain a surface electrode;

[0123] Step 6: Read Fig. 9 (a) A micromirror torsion support structure layer 14 is made of an SOI silicon wafer, and a 15 μm first bottom electrode 5, an anchor point 6, and a second bottom electrode 7 are etched on the device layer of the SOI silicon wafer using a wet etching process;

[0124] Step 7: See Fig. 9(b) The BF33 glass wafer and the SOI silicon wafer processed in step 5 and step 6 are integrated at the wafer level by using a silicon-glass anodic bonding process;

[0125] Step 8: See Fig. 9 (c) using a dry deep etching process to completely remove the 300 μm first substrate layer 14.3 of the SOI silicon wafer, thereby completing the structural release of the lower electrode 5 and the lower electrode 7;

[0126] Step 9: See Fig. 9 (c) The remaining 0.5 μm first oxide layer 14.2 of the SOI silicon wafer 14 is used as an insulating layer material and patterned to obtain an insulating layer 9;

[0127] Step 10: See Fig.10 (a) A mirror structure layer 15 is made of an SOI silicon wafer. According to the micromirror torsion angle requirement, a 10 μm mirror support structure 10 is prepared on the surface of a 20 μm device layer 15.1 of the SOI silicon wafer by a wet etching process;

[0128] Step 11: See Fig.10 (b), according to the requirements of the driving voltage and the twist angle, a twist beam 8 with a depth of 15 μm is etched on the 15 μm third device layer 16.1 of the SOI silicon wafer 16 by a wet etching process;

[0129] Step 12: See Fig.10 (c) bonding the torsion beam 8 to the mirror support structure 10 using a silicon-silicon direct bonding process;

[0130] Step 13: See Fig.10 (d) Using a wet etching process to complete the release of the torsion beam 8 structure;

[0131] Step 14: See Fig.11 (a), bonding the two ends of the torsion beam 8 to the anchor points 6 respectively using a conductive adhesive bonding process;

[0132] Step 15: See Fig.11 (b), according to the micromirror driving requirements, the second substrate layer 15.3 and the second oxide layer 15.2 of the SOI silicon wafer are completely removed by using a dry deep etching process;

[0133] Step 16: See Fig.11 (c) A 200 nm aluminum film is deposited on the surface of the thinned mirror structure layer 15 by magnetron sputtering and patterned to obtain a metal reflective layer 12. The metal reflective layer 12 is used as a mask and a surface laser processing process is used to complete the structure release of the mirror 11.

Claims

1. A two-dimensional micromechanical bidirectional torsion mirror array, characterized in that: The invention comprises an electrode substrate (1) and N×N groups of micromirror units arranged at equal intervals and arranged on the electrode substrate (1). The micromirror units comprise a micromirror torsion support structure layer (14), a through-hole electrode substrate (13) located below the micromirror torsion support structure layer (14), and a mirror structure layer (15) located above the micromirror torsion support structure layer (14). The micromirror torsion support structure layer (14) comprises an anchor point (6), a torsion beam (8), a first lower electrode (5), and a second lower electrode (7). The torsion beam (8) is suspended above the through-hole electrode substrate (13) by supporting the anchor points (6) at both ends of the torsion beam (8). The first lower electrode (5 ) and the second lower electrode (7) are symmetrically distributed about the torsion beam (8); the through-hole electrode substrate (13) comprises a first through-hole electrode (2), a second through-hole electrode (3) and a third through-hole electrode (4) arranged on the through-hole electrode substrate (13); the first through-hole electrode (2) is in contact with the first lower electrode (5); the second through-hole electrode (3) is in contact with the second lower electrode (7); the third through-hole electrode (4) is in contact with the anchor point (6); the mirror structure layer (15) comprises a mirror (11) and a mirror support structure (10); the mirror (11) is connected to the torsion beam (8) through the mirror support structure (10).

2. A two-dimensional micromechanical bidirectional torsion mirror array according to claim 1, characterized in that: The torsion beam (8) comprises a central portion (19), the mirror support structure (10) is connected to the central portion (19) of the torsion beam (8), the mirror support structure (10) and the mirror surface (11) are an integrally formed structure, the torsion beam (8) is symmetrical about the central portion (19), and the number of the anchor points (6) is two, which are respectively fitted and connected to two end portions (20) of the torsion beam (8).

3. The two-dimensional micromechanical bidirectional torsion mirror array according to claim 1, characterized in that: The micromirror unit further comprises an insulating layer (9) covering the upper surfaces of the first lower electrode (5) and the second lower electrode (7).

4. The two-dimensional micromechanical bidirectional torsion mirror array according to claim 1, characterized in that: The micromirror unit further comprises a metal reflection layer (12) covering the upper surface of the mirror surface (11).

5. The two-dimensional micromechanical bidirectional torsion mirror array according to claim 1, characterized in that: The first through-hole electrode (2), the second through-hole electrode (3) and the third through-hole electrode (4) each comprise a through-hole (21), a filling metal (22) filled in the through-hole (21) and a surface electrode (23) covering the filling metal (22).

6. A method for manufacturing a two-dimensional micromechanical bidirectional torsion mirror array as described in any one of claims 1 to 5, the method comprising the following steps: S1. Manufacturing an electrode substrate (1) using a three-dimensional integrated manufacturing process; S2, using a MEMS etching process to form a through hole (21) on the through hole electrode substrate (13); S3, aligning and bonding the electrode substrate (1) and the through-hole electrode substrate (13) using a MEMS bonding process; S4, using a metal material deposition process to complete the deposition of a filling metal (22) in the through hole (21); S5, depositing a surface electrode material on the through-hole electrode substrate (13) using a MEMS deposition process, and obtaining a surface electrode (23) through a metal material patterning process; S6, etching a first lower electrode (5), an anchor point (6), and a second lower electrode (7) on one side of the micromirror torsion support structure layer (14) using a MEMS etching process; S7, integrating the through-hole electrode substrate (13) completed in step S5 and the micromirror torsion support structure layer (14) completed in step S6 at the wafer level by using a MEMS bonding process; S8, using a MEMS thinning process to thin the micromirror torsion support structure layer (14) to a desired thickness, thereby completing the structural release of the first lower electrode (5) and the second lower electrode (7); S9, depositing an insulating material on the surfaces of the first lower electrode (5) and the second lower electrode (7) after the structure release is completed, and patterning them to obtain an insulating layer (9); S10, etching a mirror support structure (10) on one side of the mirror surface (11) using a MEMS etching process according to the micromirror torsion angle requirement; S11, according to the requirements of driving voltage and torsion angle, a torsion beam (8) is etched on one side of the micromirror torsion structure layer (16) using a MEMS etching process; S12, bonding the torsion beam (8) and the mirror support structure (10) by using a MEMS process; S13, using a MEMS thinning process to complete the release of the torsion beam (8) structure; S14, using a MEMS process to bond the two ends (20) of the torsion beam (8) to the corresponding anchor points (6) respectively; S15, thinning the mirror surface (11) to a required thickness according to the micromirror driving requirements; S16, depositing a metal material on the surface of the thinned mirror surface (11) and patterning it to obtain a metal reflective layer (12), using the metal reflective layer (12) as a mask, and using a MEMS etching process to complete the structural release of the mirror surface (11).

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