MEMS micro-mirror capable of biaxial angle feedback, and manufacturing method therefor

Abstract

A MEMS micro-mirror capable of biaxial angle feedback, and a manufacturing method therefor. The MEMS micro-mirror is provided with comb structures (40), which each comprise a movable comb (41), a fixed driving comb (42) and a fixed feedback comb (43), wherein the movable comb (41) and the fixed driving comb (42) form a driving comb group, and the movable comb (41) and the fixed feedback comb (43) form a feedback comb group. The feedback comb groups are easily compatible and integrable without affecting the performance and size of the MEMS micro-mirror, and the number of feedback comb groups is substantially equal to the number of driving comb groups, such that a feedback capacitance variation of the MEMS micro-mirror is larger, and more precise closed-loop control over the rotation angle of the micro-mirror is realized by means of a change in feedback capacitance; and the MEMS micro-mirror has a small size and a high level of integration, and manufacturing techniques therefor are fully compatible, thereby further saving on costs, and facilitating further widening of the application field of MEMS micro-mirrors.

Description

A MEMS micromirror with dual-axis angle feedback and its preparation method Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems (MEMS), and in particular to a MEMS micromirror with dual-axis angle feedback and a preparation method thereof. Background Art

[0002] MEMS micromirrors are increasingly used in industrial and consumer applications, such as LiDAR, projection displays, and 3D cameras. However, unstable environmental factors such as temperature, humidity, vibration, and shock can affect the scanning accuracy of MEMS micromirrors, leading to their failure. Therefore, it is crucial to provide feedback on the deflection angle of the MEMS micromirrors through closed-loop control, thereby maintaining a certain degree of stability through circuitry.

[0003] In the prior art, there are four common methods for monitoring the deflection angle of a MEMS micromirror: piezoelectric feedback, capacitive feedback, photoelectric feedback, and piezoresistive feedback. Comb-based capacitive feedback requires no additional components or packaging, nor does it require additional manufacturing processes, and is easy to integrate. Capacitive feedback typically comes in two forms: one is to use the same set of comb teeth as both the drive comb and the capacitive feedback comb, which greatly increases the difficulty in processing and demodulating the drive signal; the other is to set up independent drive comb groups and capacitive feedback comb groups within the device structure. Typically, these independent drive comb groups and capacitive feedback comb groups are arranged side by side, offering good compatibility and integration. However, this approach typically sacrifices the number of drive comb groups, reducing the driving force of the MEMS micromirror or impacting its performance. Therefore, how to independently set up the drive comb group and the capacitive feedback comb group without reducing the driving force of the MEMS micromirror or impacting its structure and performance presents significant challenges in setting up and integrating the capacitive feedback comb group and the drive comb group.

[0004] Therefore, how to realize the setting of the driving comb tooth group and the capacitive feedback comb tooth group without affecting the structure and performance of the MEMS micromirror, and how to achieve higher compatibility and integration of the driving comb tooth group and the capacitive feedback comb tooth group are problems that need to be solved urgently.

[0005] Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the present invention provides a dual-axis angle feedback MEMS micromirror and a method for manufacturing the same. The MEMS micromirror is provided with a comb structure, including movable comb teeth, fixed drive comb teeth, and fixed feedback comb teeth, wherein the movable comb teeth and the fixed drive comb teeth form a drive comb group, and the movable comb teeth and the fixed feedback comb teeth form a feedback comb group. Without affecting the performance and volume of the MEMS micromirror, the present invention designs a feedback comb group that is easily compatible and integrated, and the number of feedback comb groups is substantially the same as the number of drive comb groups, so that the feedback capacitance of the MEMS micromirror changes more, and higher-precision closed-loop control of the micromirror rotation angle is achieved through the change in feedback capacitance. In addition, the MEMS micromirror provided by the present invention is small in size, highly integrated, and fully compatible in manufacturing technology, which is more cost-effective and helps further expand the application field of the MEMS micromirror.

[0007] To achieve the above and other related objectives, the present invention provides a dual-axis angle feedback MEMS micromirror, comprising:

[0008] an inner frame and an outer frame, wherein the outer frame is located outside the inner frame;

[0009] a movable reflector located within the inner frame;

[0010] an elastic beam comprising a first elastic beam and a second elastic beam, wherein the first elastic beam is symmetrically arranged about the movable reflector along a first direction, connecting the inner frame and the movable reflector; and the second elastic beam is symmetrically arranged about the movable reflector along a second direction, connecting the inner frame and the outer frame, the first direction being perpendicular to the second direction;

[0011] a comb structure, provided between the inner frame and the movable reflector, and between the inner frame and the outer frame, for driving the movable reflector to twist around the first elastic beam and the second elastic beam respectively;

[0012] The comb tooth structure includes movable comb teeth, fixed drive comb teeth and fixed feedback comb teeth, wherein the fixed feedback comb teeth are located above the fixed drive comb teeth, the fixed feedback comb teeth and the movable comb teeth are located in the same plane, and the projections of the fixed drive comb teeth and the movable comb teeth on the horizontal plane are staggered; in the comb tooth structure arranged between the inner frame and the movable reflector, the fixed drive comb teeth are connected to the inner side of the inner frame; in the comb tooth structure arranged between the inner frame and the outer frame, the fixed drive comb teeth are connected to the inner side of the outer frame.

[0013] The present invention also provides a method for preparing a dual-axis angle feedback MEMS micromirror, which is used to prepare the above-mentioned MEMS micromirror and includes the following steps:

[0014] A bonding body structure is provided, comprising a substrate, a first device layer, a first insulating layer, a second device layer and a second insulating layer stacked in sequence, wherein at least fixed drive comb teeth are formed in the first device layer;

[0015] Etching the second insulating layer and the second device layer to form movable comb teeth, fixed feedback comb teeth, a movable reflector, a first elastic beam, a second elastic beam, and lower comb tooth electrode lead grooves in the second device layer, wherein the fixed feedback comb teeth are coaxially arranged with the fixed drive comb teeth, and the projections of the fixed drive comb teeth and the movable comb teeth on the horizontal plane are staggered;

[0016] removing the second insulating layer and the exposed first insulating layer;

[0017] A metal reflective layer is formed on the surface of the movable reflector, a movable comb electrode and a fixed feedback comb electrode are formed on the outer frame surface of the second device layer, and a lower comb electrode exposed on the outer frame surface is formed in the lower comb electrode lead groove, and different electrodes are isolated from each other.

[0018] The dual-axis angle feedback MEMS micromirror and its manufacturing method provided by the present invention have at least the following beneficial effects:

[0019] The MEMS micromirror provided by the present invention is provided with a comb structure, including movable comb teeth, fixed drive comb teeth, and fixed feedback comb teeth. The movable comb teeth and the fixed drive comb teeth form a drive comb group, and the movable comb teeth and the fixed feedback comb teeth form a feedback comb group. Without affecting the performance and volume of the MEMS micromirror, the present invention designs a feedback comb group that is easily compatible and integrated. The number of feedback comb groups is substantially the same as the number of drive comb groups, which increases the variation in the feedback capacitance of the MEMS micromirror and achieves higher-precision closed-loop control of the micromirror's rotation angle through the variation in feedback capacitance. In addition, the MEMS micromirror provided by the present invention is small in size, highly integrated, and fully compatible with manufacturing technologies, which is more cost-effective and helps further expand the application field of the MEMS micromirror.

[0020] The method for preparing the dual-axis angle feedback MEMS micromirror provided by the present invention also has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 shows a top view of the MEMS micromirror provided in the first and second embodiments.

[0022] FIG. 2 a shows a top view of the comb tooth structure of the first and second embodiments.

[0023] FIG. 2 b is a cross-sectional view of the comb tooth structures of the first and second embodiments.

[0024] 3a-3b are cross-sectional views of the MEMS micromirror provided in the first embodiment.

[0025] 4a-4b are cross-sectional views of a MEMS micromirror provided in the second embodiment.

[0026] 5a to 5f are cross-sectional views of the structure obtained from steps S1 to S3 of preparing the MEMS micromirror provided in Example 3. FIG.

[0027] 6a to 6d are cross-sectional views showing steps for preparing a bonding structure according to the fourth embodiment.

[0028] Component Reference Numerals 10 Inner frame 62 Lower comb-tooth electrode 20 Outer frame 63 Metal reflective layer 30 Movable reflector 100 Substrate 40 Comb-tooth structure 101 Hollow groove 41 Movable comb tooth 200 First device layer 42 Fixed drive comb tooth 300 Second device layer 43 Fixed feedback comb tooth 400 Insulation layer 51 First elastic beam 401 Isolation groove 52 Second elastic beam 410 First insulation layer 53 Additional elastic beam 420 Second insulation layer 61 Upper comb-tooth electrode 500 Base layer 611 Movable comb-tooth electrode 620 Lower comb-tooth electrode lead groove 612 Fixed feedback comb-tooth electrode DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0030] It should be noted that the illustrations provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Although the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation, the form, quantity, positional relationship and proportion of each component in actual implementation can be changed at will under the premise of realizing the technical solution of this party, and the component layout form may also be more complicated.

[0031] Example 1

[0032] This embodiment provides a dual-axis angle feedback MEMS micromirror, as shown in FIG1 , including an inner frame 10 , an outer frame 20 , a movable reflector 30 and a comb-tooth structure 40 .

[0033] As shown in FIG1 , the movable reflector 30 is located within the inner frame 10, and the outer frame 20 is located outside the inner frame 10. As an example, a first elastic beam 51 is symmetrically arranged about the movable reflector 30 along a first direction (the X-axis direction shown in FIG1 ) and is used to connect the inner frame 10 and the movable reflector 30; a second elastic beam 52 is symmetrically arranged about the movable reflector 30 along a second direction perpendicular to the first direction (the Y-axis direction shown in FIG1 ) and is used to connect the inner frame 10 and the outer frame 20.

[0034] As shown in Figure 1, the comb tooth structure 40 is arranged between the inner frame 10 and the movable reflector 30, and is used to drive the movable reflector 30 to twist with the first elastic beam 51 as the axis; the comb tooth structure 40 is also arranged between the inner frame 10 and the outer frame 20, and is used to drive the movable reflector 30 to twist with the second elastic beam 52 as the axis.

[0035] As shown in Figures 2a and 2b, the comb structure 40 includes movable comb teeth 41, fixed drive comb teeth 42, and fixed feedback comb teeth 43. The fixed feedback comb teeth 43 are located above the fixed drive comb teeth 42 and coplanar with the movable comb teeth 41. The projections of the fixed drive comb teeth 42 and the movable comb teeth 41 on the horizontal plane are staggered. When the movable comb teeth 41 rotate, the capacitance formed between the fixed feedback comb teeth 43 and the movable comb teeth 41 changes. This capacitance change provides real-time feedback on the rotation angle. For example, when the movable reflector 30 is twisted about the first elastic beam 51, the capacitance of the movable comb teeth 41 and the fixed feedback comb teeth 43 located between the inner frame 10 and the movable reflector 30 decreases simultaneously. When the movable reflector 30 is twisted about the second elastic beam 52, the capacitance of the movable comb teeth 41 and the fixed feedback comb teeth 43 located between the inner frame 10 and the outer frame 20 decreases simultaneously.

[0036] As an example, there are isolation grooves 401 or insulating filling grooves (not shown in the figure) between the fixed drive comb teeth 42, between the fixed feedback comb teeth 43, and between the fixed feedback comb teeth 43 and the movable comb teeth 41, and there is a first insulating layer 410 between the fixed feedback comb teeth 43 and the fixed drive comb teeth 42 to achieve electrical insulation.

[0037] As shown in FIG1 , in the comb tooth structure disposed between the inner frame 10 and the outer frame 20, the movable comb teeth 41, the fixed drive comb teeth 42, and the fixed feedback comb teeth 43 all extend along a first direction (the X-axis direction shown in FIG1 ), wherein the movable comb teeth 41 are connected to the outer side of the inner frame 10, and the fixed drive comb teeth 42 and the fixed feedback comb teeth 43 are both connected to the inner side of the outer frame 20. In the comb tooth structure disposed between the inner frame 10 and the movable reflector 30, the movable comb teeth 41, the fixed drive comb teeth 42, and the fixed feedback comb teeth 43 all extend along a second direction (the Y-axis direction shown in FIG1 ), wherein the movable comb teeth 41 are connected to the movable reflector 30, and the fixed drive comb teeth 42 and the fixed feedback comb teeth 43 are both connected to the inner side of the inner frame 10. As an example, on the projection plane formed by the first direction and the second direction (the XY plane shown in Figure 2a), the length of the fixed feedback comb tooth 43 is less than or equal to the length of the fixed drive comb tooth 42, and the width of the fixed feedback comb tooth 43 is less than or equal to the width of the fixed drive comb tooth 42.

[0038] As shown in Figures 3a and 3b, the MEMS micromirror further includes a substrate 100. As an example, the substrate 100 is positioned below the inner frame 10, outer frame 20, movable reflector 30, first elastic beam 51, second elastic beam 52, and comb-tooth structure 40. An insulating layer 400 is provided on the bottom surface of the substrate 100. A hollow groove 101 is provided in the substrate 100 to provide movement space for the movable reflector 30, first elastic beam 51, second elastic beam 52, comb-tooth structure 40, and inner frame 10. In this embodiment, as shown in Figure 3a, the hollow groove 101 is a closed-bottom groove; in another alternative embodiment, as shown in Figure 3b, the hollow groove 101 is a through groove extending vertically.

[0039] As shown in Figures 3a and 3b, the MEMS micromirror further includes an additional elastic beam 53, an upper comb-tooth electrode 61, a lower comb-tooth electrode 62, and a metal reflective layer 63. As an example, the additional elastic beam 53 is located below the second elastic beam 52 and is isolated from the second elastic beam 52 by a first insulating layer 410. The upper comb-tooth electrode 61 and the lower comb-tooth electrode 62 are both located in the outer frame 20. As shown in Figure 1, the upper comb-tooth electrode 61 includes a movable comb-tooth electrode 611 and a fixed feedback comb-tooth electrode 612. The metal reflective layer 63 is located on the surface of the movable reflector 30.

[0040] As an example, the additional elastic beam 53 and the fixed drive comb teeth 42 are located in the first device layer 200, and an insulating layer 400 is provided between the first device layer 200 and the substrate 100; the movable reflector 30, the first elastic beam 51, the second elastic beam 52, the movable comb teeth 41 and the fixed feedback comb teeth 43 are located in the second device layer 300, and a first insulating layer 410 is provided between the second device layer 300 and the first device layer 200; the upper comb tooth electrode 61 is provided on the surface of the second device layer 300, and the lower comb tooth electrode 62 is provided on the surface of the first device layer 200 and is exposed on the surface of the outer frame. In this embodiment, the movable comb teeth 41 are led out to the movable comb tooth electrode 611 through the first elastic beam 51 and the second elastic beam 52; the fixed feedback comb teeth 43 connected to the inner side of the inner frame 10 are led out to the fixed feedback comb tooth electrode 612 through the first elastic beam 51 and the second elastic beam 52, and the fixed feedback comb teeth 43 connected to the inner side of the outer frame 20 are led out to the corresponding fixed feedback comb tooth electrode 612 through the internal connection of the layer; the fixed drive comb teeth 42 connected to the inner side of the inner frame 10 are led out to the corresponding lower comb tooth electrode 62 through the additional elastic beam 53, and the fixed drive comb teeth 42 connected to the inner side of the outer frame 20 are led out to the corresponding lower comb tooth electrode 62 through the internal connection of the layer, and different electrodes are isolated from each other.

[0041] As an example, a laser, position detector, lens, etc. (not shown) are also provided directly below the movable reflector 30. The laser beam is reflected by the back surface of the movable reflector 30 and then received by the position detector. The intensity or position of the beam received by the position detector can be used to provide feedback on the rotation angle of the movable reflector 30. Therefore, instead of using capacitive feedback, photoelectric feedback can also be implemented using lasers, position detectors, lenses, etc., and both capacitive feedback and photoelectric feedback can be compatible with closed-loop angle control, making the design more flexible.

[0042] Example 2

[0043] This embodiment also provides a dual-axis angle feedback MEMS micromirror, as shown in Figures 4a and 4b, comprising an inner frame 10, an outer frame 20, a movable reflector 30, and a comb structure 40. The similarities between this embodiment and the MEMS micromirror provided in Example 1 are not repeated here. The differences are as follows:

[0044] As shown in Figures 4a and 4b, the MEMS micromirror includes an upper comb electrode 61 and a lower comb electrode 62 located within the outer frame 20. As shown in Figure 1, the upper comb electrode 61 includes a movable comb electrode 611 and a fixed feedback comb electrode 612. As an example, the upper comb electrode 61 is disposed on the surface of the second device layer 300, while the lower comb electrode 62 is disposed on the surface of the first device layer 200 and exposed on the outer frame surface. In this embodiment, the movable comb teeth 41 are connected to the movable comb electrode 611 via the first and second elastic beams 51 and 52; the fixed feedback comb teeth 43 connected to the inner side of the inner frame 10 are connected to the fixed feedback comb electrode 612 via the first and second elastic beams 51 and 52; the fixed feedback comb teeth 43 connected to the inner side of the outer frame 20 are connected to the corresponding fixed feedback comb electrode 612 via internal layer connections; and the fixed drive comb teeth 42 are connected to the corresponding lower comb electrode 62 via internal layer connections, with the different electrodes being isolated from each other.

[0045] As an example, a hollow groove 101 is provided in the substrate 100 to provide movement space for the movable reflector 30 and the first elastic beam 51, the second elastic beam 52, the comb structure 40, and the inner frame 10. In this embodiment, as shown in Figure 4a, the hollow groove 101 is a groove with a closed bottom; in another optional embodiment, as shown in Figure 4b, the hollow groove 101 is a through groove that passes through from top to bottom.

[0046] Example 3

[0047] This embodiment provides a method for manufacturing a dual-axis angle feedback MEMS micromirror. The method is used to manufacture the MEMS micromirror described in the first embodiment, and includes the following steps:

[0048] S1: providing a bonding structure, comprising a substrate, a first device layer, a first insulating layer, a second device layer, and a second insulating layer stacked in sequence, wherein at least fixed drive comb teeth are formed in the first device layer;

[0049] As shown in FIG5a , a dual-device layer substrate is provided, comprising a first device layer 200, a first insulating layer 410, a second device layer 300, a second insulating layer 420, and a base layer 500 stacked in sequence. As an example, the dual-device layer substrate includes, but is not limited to, a dual-device layer being an SOI low-resistance silicon wafer and a base layer 500 being a high-resistance silicon wafer, whereby the first device layer 200, the second device layer 300, and the base layer 500 are silicon material layers, while the first insulating layer 410 and the second insulating layer 420 are silicon oxide layers. Of course, according to actual needs, the dual-device layer substrate can also be made of other materials, for example, the first device layer 200, the second device layer 300, and / or the base layer 500 are semiconductor material layers such as germanium, silicon germanium, or silicon carbide, and the first insulating layer 410 and / or the second insulating layer 420 are dielectric layers such as silicon nitride, and this is not strictly limited.

[0050] As shown in Figure 5b, the first device layer 200 and the first insulating layer 410 are etched to form fixed drive comb teeth 42, the underlying structure of the inner frame 10, the underlying structure of the outer frame 20, and the additional elastic beams 53 in the first device layer 200. Referring to Figure 1, in the comb structure disposed between the inner frame 10 and the outer frame 20, the fixed drive comb teeth 42 are connected to the inner side of the outer frame 20; in the comb structure disposed between the inner frame 10 and the movable reflector 30, the fixed drive comb teeth 42 are connected to the inner side of the inner frame 10.

[0051] In this step, a photoresist layer or the like is applied to the surface of the first device layer 200, and patterning is performed to define the desired pattern. Dry and / or wet etching is then performed to form the fixed drive comb teeth 42, the inner frame 10, the outer frame 20, and the additional elastic beams 53. As an example, the fixed drive comb teeth 42 connected to the inner side of the inner frame are subsequently led to the corresponding lower comb tooth electrodes 62 via the additional elastic beams 53, and the fixed drive comb teeth 42 connected to the inner side of the outer frame 20 are subsequently led to the corresponding lower comb tooth electrodes 62 via internal layer connections. Multiple fixed drive comb teeth 42 are arranged in parallel and spaced apart, and the gaps between the multiple fixed drive comb teeth 42 expose the second device layer 300.

[0052] As shown in Figure 5c, a substrate 100 is provided, and an insulating layer 400 is formed on both surfaces of the substrate 100. For example, the substrate 100 can be a silicon substrate, and a double-sided insulating layer is obtained by thermal oxidation treatment; a hollow groove 101 is formed in the substrate 100, and the hollow groove 101 has an opening on the front side of the substrate 100. The hollow groove 101 is used to provide movement space for the movable reflector 30, the inner frame 10, the comb tooth structure 40, the first elastic beam 51 and the second elastic beam 52 prepared subsequently.

[0053] As shown in Figure 5d, the side of the dual-device-layer substrate with the first device layer 200 is bonded to the front surface of the substrate 100. The base layer 500 is removed by etching and / or chemical mechanical polishing to form a bonded structure. As an example, the fixed drive comb teeth 42, the inner frame 10, and the additional elastic beams 53 are positioned above the hollow groove 101.

[0054] S2: etching the second insulating layer and the second device layer to form movable comb teeth, fixed feedback comb teeth, a movable reflector, a first elastic beam, a second elastic beam, and a lower comb tooth electrode lead groove in the second device layer;

[0055] As shown in FIG5e, the second insulating layer 420 and the second device layer 300 are etched to form the top structure of the inner frame 10, the top structure of the outer frame 20, the movable comb teeth 41, the fixed feedback comb teeth 43, the movable reflector 30, the first elastic beam 51, the second elastic beam 52, and the lower comb electrode lead groove 620 in the second device layer 300. Referring to FIG1 and FIG2b, the movable reflector 30 is located within the inner frame 10 and connected to the inner frame 10 by the first elastic beam 51. The outer frame 20 is located outside the inner frame 10 and connected to the inner frame 10 by the second elastic beam 52. The fixed feedback comb teeth 43 and the fixed drive comb teeth 42 are coaxially arranged, and the projections of the fixed drive comb teeth 42 and the movable comb teeth 41 on the horizontal plane are staggered.

[0056] As shown in Figure 1, in the comb tooth structure arranged between the inner frame 10 and the outer frame 20, the movable comb teeth 41 are connected to the outer side of the inner frame 10, and the fixed drive comb teeth 42 and the fixed feedback comb teeth 43 are connected to the inner side of the outer frame 20; in the comb tooth structure arranged between the inner frame 10 and the movable reflector 30, the movable comb teeth 41 are connected to the movable reflector 30, and the fixed drive comb teeth 42 and the fixed feedback comb teeth 43 are connected to the inner side of the inner frame 10.

[0057] S3: removing the second insulating layer and the exposed first insulating layer.

[0058] As an example, the second insulating layer 420 and the exposed first insulating layer 410 are removed to form the structure shown in FIG. 5 f .

[0059] Next, an upper comb-tooth electrode 61 is formed on the surface of the outer frame 20 of the second device layer 300. As shown in FIG1 , the upper comb-tooth electrode 61 includes a movable comb-tooth electrode 611 and a fixed feedback comb-tooth electrode 612. A metal reflective layer 63 is formed on the surface of the movable reflector 30. A lower comb-tooth electrode 62 exposed on the surface of the outer frame is formed in the lower comb-tooth electrode lead groove 620, ultimately forming the structure shown in FIG3a .

[0060] As an example, the upper surface of the second device layer 300 is the surface of the outer frame 20. Upper comb-tooth electrodes 61 are formed on the outer frame 20, including a movable comb-tooth electrode 611 and a fixed feedback comb-tooth electrode 612. The movable comb-tooth electrode 611 is electrically connected to the movable comb teeth 41 via the first elastic beam 51 and the second elastic beam 52, and is generally a shared ground electrode. Lower comb-tooth electrode lead slots 620 expose the first device layer 200 to allow the lower comb-tooth electrodes 62 to be exposed on the surface of the outer frame 20. As shown in FIG1 , there are generally four lower comb-tooth electrodes 62. Two of these electrodes are independently electrically connected to the fixed drive comb teeth 42 connected to the inner side of the inner frame 10 to provide different voltages to rotate the movable reflector 30 about the first elastic beam 51. The other two electrodes are independently electrically connected to the fixed drive comb teeth 42 connected to the inner side of the outer frame 20 to provide different voltages to rotate the movable reflector 30 about the second elastic beam 52. The different lower comb-tooth electrodes 62 are isolated from each other. The metal reflective layer 63 and the electrodes may be formed by the same process or different processes, including but not limited to a sputtering process, and the materials include but are not limited to a single metal or alloy such as gold, silver, copper, and aluminum.

[0061] In another optional embodiment, after forming the structure shown in Figure 3a, the step of opening a hole on the back side of the substrate 100 is also included. As shown in Figure 3b, the hollow groove 101 in the substrate 100 is a through groove that passes through from top to bottom to provide movement space for the movable reflector 30 and the first elastic beam 51, the second elastic beam 52, the comb tooth structure 40, and the inner frame 10.

[0062] Example 4

[0063] This embodiment provides a method for preparing a dual-axis angle feedback MEMS micromirror. The method is used to prepare the MEMS micromirror described in the second embodiment, and includes the following steps:

[0064] S1: providing a bonding structure, comprising a substrate, a first device layer, a first insulating layer, a second device layer, and a second insulating layer stacked in sequence, wherein at least fixed drive comb teeth are formed in the first device layer;

[0065] S2: etching the second insulating layer and the second device layer to form movable comb teeth, fixed feedback comb teeth, a movable reflector, a first elastic beam, a second elastic beam, and a lower comb tooth electrode lead groove in the second device layer;

[0066] S3: removing the second insulating layer and the exposed first insulating layer.

[0067] The method for preparing the MEMS micromirror provided in this embodiment is similar to that in the third embodiment and is not described in detail here. The difference is that providing a bonding structure includes:

[0068] As shown in Figure 6a, a single device layer substrate is provided, comprising a stacked substrate 100, a first device layer 200, and a first insulating layer 410. Insulating layers 400 are formed on both surfaces of the substrate 100. For example, the substrate 100 may be a silicon substrate, which is thermally oxidized to obtain double-sided insulating layers.

[0069] As shown in FIG. 6 b , the first device layer 200 and the first insulating layer 410 are etched to form fixed driving comb teeth 42 in the first device layer 200 .

[0070] Next, another single-device layer substrate is provided, as shown in Figure 6c, including a second device layer 300, a second insulating layer 420 and a base layer 500 stacked in sequence; the side of the single-device layer substrate having the first device layer 200 is bonded to the side of the single-device layer substrate having the second device layer 300 to form a bonded structure; finally, the base layer 500 is removed to form the structure shown in Figure 6d.

[0071] In the MEMS micromirror prepared in this embodiment, the movable comb teeth 41 are led out to the movable comb tooth electrode 611 through the first elastic beam 51 and the second elastic beam 52; the fixed feedback comb teeth 43 connected to the inner side of the inner frame 10 are led out to the fixed feedback comb tooth electrode 612 through the first elastic beam 51 and the second elastic beam 52, and the fixed feedback comb teeth 43 connected to the inner side of the outer frame 20 are led out to the corresponding fixed feedback comb tooth electrode 612 through the internal connection of the layer; the fixed drive comb teeth 42 are led out to the corresponding lower comb tooth electrode 62 through the internal connection of the layer, and different electrodes are isolated from each other.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A dual-axis angle feedback MEMS micromirror, characterized in that: include: An inner frame and an outer frame, wherein the outer frame is located outside the inner frame; a movable reflector located within the inner frame; An elastic beam, comprising a first elastic beam and a second elastic beam, wherein the first elastic beam is symmetrically arranged about the movable reflector along a first direction, connecting the inner frame and the movable reflector; the second elastic beam is symmetrically arranged about the movable reflector along a second direction, connecting the inner frame and the outer frame, and the first direction is perpendicular to the second direction; A comb structure, disposed between the inner frame and the movable reflector, and between the inner frame and the outer frame, for driving the movable reflector to twist with the first elastic beam and the second elastic beam as axes; The comb tooth structure includes movable comb teeth, fixed drive comb teeth and fixed feedback comb teeth, wherein the fixed feedback comb teeth are located above the fixed drive comb teeth, the fixed feedback comb teeth and the movable comb teeth are located in the same plane, and the projections of the fixed drive comb teeth and the movable comb teeth on the horizontal plane are staggered; in the comb tooth structure arranged between the inner frame and the movable reflector, the fixed drive comb teeth are connected to the inner side of the inner frame; in the comb tooth structure arranged between the inner frame and the outer frame, the fixed drive comb teeth are connected to the inner side of the outer frame.

2. The dual-axis angle feedback MEMS micromirror according to claim 1, characterized in that: In the comb tooth structure arranged between the inner frame and the outer frame, the movable comb teeth, the fixed drive comb teeth and the fixed feedback comb teeth all extend along the first direction; in the comb tooth structure arranged between the inner frame and the movable reflector, the movable comb teeth, the fixed drive comb teeth and the fixed feedback comb teeth all extend along the second direction.

3. The dual-axis angle feedback MEMS micromirror according to claim 1, characterized in that: On the projection plane formed by the first direction and the second direction, the length of the fixed feedback comb teeth is less than or equal to the length of the fixed drive comb teeth, and the width of the fixed feedback comb teeth is less than or equal to the width of the fixed drive comb teeth.

4. The dual-axis angle feedback MEMS micromirror according to claim 1, characterized in that: There are isolation grooves or insulation filling grooves between the fixed drive comb teeth, between the fixed feedback comb teeth, and between the fixed feedback comb teeth and the movable comb teeth, and there is a first insulation layer between the fixed feedback comb teeth and the fixed drive comb teeth.

5. The dual-axis angle feedback MEMS micromirror according to claim 1, characterized in that: It also includes a substrate, which is located below the inner frame, the outer frame, the movable reflector, the elastic beam and the comb-tooth structure. A hollow groove is provided in the substrate to provide movement space for the movable reflector, the elastic beam, the comb-tooth structure and the inner frame, and the hollow groove is a groove with a closed bottom or a through groove that passes through from top to bottom.

6. The dual-axis angle feedback MEMS micromirror according to claim 1, characterized in that: Also includes: an additional elastic beam, located below the second elastic beam and isolated from the second elastic beam; An upper comb-tooth electrode and a lower comb-tooth electrode, both of which are located in the outer frame, wherein the upper comb-tooth electrode includes a movable comb-tooth electrode and a fixed feedback comb-tooth electrode; The movable comb teeth are led out to the movable comb tooth electrode through the elastic beam; the fixed feedback comb teeth connected to the inner side of the inner frame are led out to the fixed feedback comb tooth electrode through the elastic beam, and the fixed feedback comb teeth connected to the inner side of the outer frame are led out to the corresponding fixed feedback comb tooth electrode through the internal connection of the layer; the fixed drive comb teeth connected to the inner side of the inner frame are led out to the corresponding lower comb tooth electrode through the additional elastic beam, and the fixed drive comb teeth connected to the inner side of the outer frame are led out to the corresponding lower comb tooth electrode through the internal connection of the layer; different electrodes are isolated from each other.

7. The dual-axis angle feedback MEMS micromirror according to claim 1, characterized in that: Also includes: An upper comb-tooth electrode and a lower comb-tooth electrode, both of which are located in the outer frame, wherein the upper comb-tooth electrode includes a movable comb-tooth electrode and a fixed feedback comb-tooth electrode; The movable comb teeth are led out to the movable comb tooth electrode through the elastic beam; the fixed feedback comb teeth connected to the inner side of the inner frame are led out to the fixed feedback comb tooth electrode through the elastic beam, and the fixed feedback comb teeth connected to the inner side of the outer frame are led out to the corresponding fixed feedback comb tooth electrode through the internal connection of the layer; the fixed drive comb teeth are led out to the corresponding lower comb tooth electrode through the internal connection of the layer; different electrodes are isolated from each other.

8. A method for preparing a dual-axis angle feedback MEMS micromirror, characterized in that: The method is used to prepare the MEMS micromirror according to any one of claims 1 to 7, comprising the following steps: A bonding body structure is provided, comprising a substrate, a first device layer, a first insulating layer, a second device layer and a second insulating layer stacked in sequence, wherein at least fixed drive comb teeth are formed in the first device layer; Etching the second insulating layer and the second device layer to form movable comb teeth, fixed feedback comb teeth, a movable reflector, a first elastic beam, a second elastic beam and a lower comb tooth electrode lead groove in the second device layer, wherein the fixed feedback comb teeth are coaxially arranged with the fixed drive comb teeth, and the projections of the fixed drive comb teeth and the movable comb teeth on the horizontal plane are staggered; removing the second insulating layer and the exposed first insulating layer; A metal reflective layer is formed on the surface of the movable reflector, and a movable comb is formed on the outer frame surface of the second device layer. Tooth electrodes and fixed feedback comb-tooth electrodes are formed in the lower comb-tooth electrode lead grooves to expose the lower comb-tooth electrodes on the surface of the outer frame, and different electrodes are isolated from each other.

9. The method for preparing a dual-axis angle feedback MEMS micromirror according to claim 8, characterized in that: Forming the bonding body structure comprises: Providing a double-device layer substrate, comprising a first device layer, a first insulating layer, a second device layer, a second insulating layer and a substrate layer stacked in sequence; Etching the first device layer and the first insulating layer to form the fixed driving comb teeth and the additional elastic beam in the first device layer; Providing a substrate, forming a hollow groove in the substrate, wherein the hollow groove has an opening on the front side of the substrate; Bonding the side of the double-device layer base having the first device layer to the front side of the substrate to form a bonding structure, wherein the fixed driving comb teeth, the inner frame and the additional elastic beam are located above the hollow groove; The base layer is removed.

10. The method for preparing a dual-axis angle feedback MEMS micromirror according to claim 8, characterized in that: Forming the bonding body structure comprises: Providing a single device layer substrate, comprising a substrate, a first device layer and a first insulating layer stacked in sequence; Etching the first device layer and the first insulating layer to form the fixed driving comb teeth in the first device layer; Providing another single device layer substrate, comprising sequentially stacking a second device layer, a second insulating layer and a substrate layer; Bonding a side of the single device layer substrate having the first device layer to a side of the single device layer base having the second device layer to form a bonded structure; The base layer is removed.

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