Micromirror with diaphragm deflection angle threshold detection structure and processing technology thereof

Abstract

The present application provides a kind of micro mirror with diaphragm deflection angle threshold detection structure and its processing technology, the micro mirror includes: first substrate, for installing micro mirror structure;Second substrate is bonded on the first substrate, and the second substrate is located in one side of the first substrate;Forming the detection column structure of differential capacitance, is arranged in the inside of the second substrate, the detection column structure is formed by etching on the second substrate;And electrode piece, is arranged on the detection column structure, and the electrode piece is located between the detection column structure and the micro mirror structure.The present application provides a kind of micro mirror with diaphragm deflection angle threshold detection structure and its processing technology, the micro mirror provides a more stable threshold capacitance, can be completely differential detection output, accurately detects the deflection angle threshold θ of micro mirror, is favorable for the improvement of control precision.

Description

Technical Field

[0001] This invention relates to the field of micromirror detection technology, and in particular to a micromirror with a diaphragm deflection angle threshold detection structure and its fabrication process. Background Technology

[0002] Micromirrors are a type of micro / nano chip that can effectively control optical paths and are widely used in projection, imaging, laser navigation, and other fields. Currently, the most commonly used micromirrors include electrostatic, electromagnetic, piezoelectric, and electrothermal types. A large proportion of currently used micromirrors employ open-loop control without angle feedback. A serious drawback of this type of micromirror is the lack of effective angle feedback, leading to inaccurate micromirror control and consequently, problems such as projection and imaging drift, and navigation deviation.

[0003] Current devices for detecting micromirrors cannot achieve fully differential detection output and cannot accurately provide the deflection angle threshold of the micromirror, resulting in low signal-to-noise ratio and low sensitivity of the detection signal, which is not conducive to improving control accuracy. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned problems in the prior art and provide a micromirror with a diaphragm deflection angle threshold detection structure and its processing technology. The micromirror can perform completely differential detection output, accurately detect the diaphragm deflection angle threshold of the micromirror, and is beneficial to improving control accuracy.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] This invention provides a micromirror with a diaphragm deflection angle threshold detection structure, the micromirror comprising:

[0007] The first substrate is used to mount the micromirror structure;

[0008] The second substrate is bonded to the first substrate, and the second substrate is located on one side of the first substrate;

[0009] A detection post structure forming a differential capacitance is disposed inside the second substrate, the detection post structure being formed by etching on the second substrate; and

[0010] An electrode sheet is disposed on the detection column structure, and the electrode sheet is located between the detection column structure and the micromirror structure.

[0011] In one embodiment of the present invention, the first substrate includes:

[0012] plate body;

[0013] A first insulating layer is disposed on the plate body;

[0014] A first metal layer, disposed on the first insulating layer, is used for electrical conduction with the detection column structure and for bonding the micromirror structure; and

[0015] The second insulating layer is disposed on the first metal layer.

[0016] In one embodiment of the present invention, the first substrate further includes a second metal layer, which is located on the second insulating layer and is used to bond the second substrate.

[0017] In one embodiment of the present invention, the detection column structure includes N detection column ring groups, and the center points of the N detection column ring groups coincide.

[0018] In one embodiment of the present invention, the detection column ring group includes M detection columns, and the M detection columns are centrally symmetrical.

[0019] In one embodiment of the present invention, the detection column ring assembly further includes a dielectric layer located at one end of the detection column and between the detection column and the electrode sheet.

[0020] In one embodiment of the present invention, the micromirror further includes a micromirror structure, the micromirror structure being mounted on the first substrate and the micromirror structure being fitted onto the second substrate.

[0021] The present invention also provides a micromirror fabrication process, the fabrication process comprising:

[0022] Producing the first substrate;

[0023] The second substrate is bonded to the first substrate;

[0024] Etching the detection pillar structure on the first substrate; and

[0025] The micromirror structure is bonded to the first substrate to obtain the micromirror.

[0026] In one embodiment of the present invention, the manufacturing process of the first substrate includes:

[0027] Take a piece of plate;

[0028] A first insulating layer is grown on the plate.

[0029] A first metal layer is grown on the first insulating layer, and the first metal layer is etched.

[0030] A second insulating layer is grown on the first metal layer, and the second insulating layer is etched to expose the first metal layer to air; and

[0031] A second metal layer is grown on the second insulating layer and the second metal layer is etched, the second metal layer being used to bond the second substrate.

[0032] In summary, this invention provides a micromirror with a diaphragm deflection angle threshold detection structure and its fabrication process. This micromirror, by setting different dielectric constants, cross-sectional areas, or heights of the detection pillars in each detection pillar ring group, can find, according to the capacitance formula C = εSd, that at a certain point, the capacitance between each detection pillar ring group and the micromirror is equal, thus obtaining the capacitance threshold. This allows the determination of the micromirror's deflection angle threshold θ. Because different dielectric constants, cross-sectional areas, or heights of the detection pillars in each detection pillar ring group create a difference, a more stable capacitance threshold is provided, which is more stable than measuring absolute capacitance. It allows for completely differential detection output, accurately detecting the micromirror's deflection angle threshold θ, which is beneficial for improving control accuracy. The micromirror structure and the first substrate are bonded at the wafer level, resulting in high consistency. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0034] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure of a micromirror according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0042] Figure 9 This is a schematic diagram of the structure of the second substrate and detection column according to an embodiment of the present invention;

[0043] Figure 10 This is a schematic diagram of the structure of the lens deflection state when the detection column height is different according to the present invention;

[0044] Figure 11 This is a schematic diagram of the structure of the lens deflection state when the detection column height is different according to the present invention;

[0045] Figure 12 This is a schematic diagram of the structure of the lens deflection state when the transverse cross-sectional area of ​​the detection column is different according to the present invention;

[0046] Figure 13 This is a schematic diagram of the structure of the lens deflection state when the transverse cross-sectional area of ​​the detection column is different according to the present invention;

[0047] Figure 14 This is a schematic diagram of the structure of the lens under different dielectric constants of the detection column in this invention;

[0048] Figure 15 This is a schematic diagram of the structure of the lens under different dielectric constants of the detection column in this invention;

[0049] Figure 16 This is the present invention. Figure 2 Top view.

[0050] Figure 17 This is a schematic diagram of the structure of the first substrate of the present invention;

[0051] Figures 18-a to 18-h This is a process diagram of the micromirror of the present invention.

[0052] The numbers in the diagram are explained as follows: 1-body, 2-outer frame, 3-cantilever beam, 4-lens, 5-second substrate, 6-electrode sheet, 7-detection column, 8-dielectric layer, 9-detection column structure, 10-micromirror structure, 11-first insulating layer, 12-first metal layer, 13-second insulating layer, 14-second metal layer. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0054] Please see Figure 1This invention provides a micromirror, which includes a micromirror structure 10. The micromirror structure 10 includes an outer frame 2, a cantilever beam 3, and a lens 4. The outer frame 2 is disposed on the micromirror. This application does not limit the specific structure of the outer frame 2. In one embodiment of this invention, the outer frame 2 consists of two bases with perforated holes. The cantilever beam 3 is disposed between the two bases and located at both ends of the bases, serving to connect the two bases. The cantilever beam 3 can be a T-shaped structure, but is not limited thereto. The two ends of the lens 4 are connected to one end of the two cantilever beams 3, and a gap L is formed between the lens 4 and the top of the micromirror. L can be 20-30 μm, for example, 25 μm. A gap D is formed between the sidewall of the lens 4 and the inner wall of the outer frame 2.

[0055] Please see Figures 2 to 9 , Figure 16 , Figure 17 The present invention also provides a micromirror with a diaphragm deflection angle threshold detection structure. This micromirror can perform completely differential detection output, accurately detecting the deflection angle threshold of the micromirror, which is beneficial to improving control accuracy. Specifically, the micromirror includes a first substrate 1 and a second substrate 5. The first substrate 1 is used to mount the micromirror structure 10. Specifically, the first substrate includes a plate body 1, a first insulating layer 11, a first metal layer 12, a second insulating layer 13, and a second metal layer 14. The plate body 1 can be a glass plate or a silicon plate. The first insulating layer 11 is disposed on the plate body 1. The first metal layer 12 is disposed on the first insulating layer 11, used for electrical conduction with the detection post structure, and for leading out the signal of the detection post structure, while also being used to bond the micromirror structure 10. The second insulating layer 13 is disposed on the first metal layer 12, and the portion of the first metal layer 12 in contact with the detection post structure is exposed to air, facilitating the bonding of the detection post structure to the first metal layer 12. The second metal layer 14 is located on the second insulating layer 13 and is used to bond the second substrate 5. The materials of the first insulating layer 11 and the second insulating layer 13 can be silicon oxide, but are not limited thereto. The second substrate 5 is bonded to the first substrate 1, and the second substrate 5 is located on one side of the first substrate 1. The second substrate 5 can be a silicon plate, for example, low-resistivity silicon, but is not limited thereto. The shape of the second substrate 5 matches the shape of the micromirror structure 10, and the second substrate 5 is embedded in the micromirror structure 10. The specific processing method for the second substrate 5 can be as follows: a silicon plate is bonded to the first substrate 1, and then the excess portion around the silicon plate is etched away using a silicon etching process, so that the second substrate 5 can be embedded within the micromirror structure 10. The second substrate 5 can limit the position of the micromirror structure 10, preventing the micromirror structure 10 from deflecting at an excessive angle.

[0056] Please see Figures 2 to 9 , Figure 16In one embodiment of the present invention, the micromirror further includes a detection post structure forming a differential capacitor and an electrode sheet 6. The detection post structure is disposed inside the second substrate 5 and is formed by etching on the second substrate 5. The second substrate 5 can protect the detection post structure to prevent it from breaking when the micromirror structure 10 deflects. This application does not limit the specific structure of the detection post structure. In one embodiment of the present invention, the detection post structure consists of N detection post ring groups 9, with the center points of the N detection post ring groups 9 coinciding. Each detection post ring group 9 consists of M detection posts 7, and the M detection posts 7 are centrally symmetrical. Here, N is a positive integer greater than or equal to two, and M is a positive even number greater than or equal to two. The number of detection posts 7 in the detection post ring group 9 is a positive even number greater than or equal to two, which can detect the angle threshold θ in each axial direction of the micromirror. According to the capacitance formula C=εSd, where C is the capacitance, ε is the dielectric constant, and d is the distance between the top of the detection post 7 and the bottom of the micromirror lens 4, differential capacitance can be achieved by setting different lateral cross-sectional areas of the detection post 7, different heights of the detection post 7, and different dielectric layers 8 at the top of the detection post 7. An angle is found such that the capacitance values ​​formed between several detection posts 7 and the micromirror on the same axis are equal, thereby determining the angle threshold θ.

[0057] Please see Figures 3 to 6 , Figure 9 , Figure 16 In one embodiment of the present invention, the transverse cross-sectional area of ​​the detection posts 7 in different detection post ring groups 9 is different, and the transverse cross-sectional area of ​​the detection posts 7 can gradually increase from the center point of the second substrate 5 to the edge of the second substrate 5, such as... Figure 11 As shown in Figure 12, the lateral cross-sectional area of ​​the detection post 7 from the center point of the second substrate 5 to the edge of the second substrate 5 can also be gradually reduced. At this time, the height of each detection post 7 and the dielectric layer 8 on the surface of the detection post 7 remain the same, so that the capacitance C1 = C2 = C3, thereby determining the angle threshold θ.

[0058] Please see Figure 2 and Figure 7 , Figure 16 In one embodiment of the present invention, the heights of the detection columns 7 in different detection column ring groups 9 are different, and the height of the detection columns 7 can gradually increase from the center point of the second substrate 5 to the edge of the second substrate 5, such as... Figure 9 As shown, the height of the detection post 7 from the center point of the second substrate 5 to the edge of the second substrate 5 can also be gradually reduced, such as... Figure 10 As shown. At this time, the lateral cross-sectional area of ​​each detection post 7 and the dielectric layer 8 on the surface of the detection post 7 remain the same, so that the capacitance C1 = C2 = C3, thereby determining the angle threshold θ.

[0059] Please see Figure 8 , Figure 15 In one embodiment of the present invention, the dielectric layer 8 of the detection pillars 7 in different detection pillar ring groups 9 is different, and the dielectric constant of the detection pillars 7 can gradually increase from the center point of the second substrate 5 to the edge of the second substrate 5, such as... Figure 13 As shown, the dielectric constant of the detection post 7 can also gradually decrease from the center point of the second substrate 5 to the edge of the second substrate 5, such as... Figure 14 As shown. At this time, the lateral cross-sectional area and height of each detection column 7 remain the same. Specifically, a dielectric layer 8 of different thicknesses of the same thickness can be coated on the surface of the electrode sheet 6, so that the dielectric constants on different detection columns 7 are different, making the capacitance C1=C2=C3, thereby determining the angle threshold θ.

[0060] Please see Figures 2 to 9 In one embodiment of the present invention, the electrode sheet 6 is disposed between the detection column structure and the micromirror structure 10. Specifically, the electrode sheet 6 can be disposed on one end of the detection column 7 near the micromirror structure 10, or on one side of the micromirror structure 10 near the detection column 7, which simplifies the process. Alternatively, the electrode sheet 6 can be disposed on both one end of the detection column 7 near the micromirror structure 10 and one side of the micromirror structure 10 near the detection column 7, forming electrodes on both the detection column 7 and the micromirror structure 10, thereby achieving the goal of eliminating stray signals and obtaining pure differential mode signals, which is beneficial for anti-interference signals.

[0061] Please see Figures 18-a to 18-h The present invention also provides a micromirror processing technology, the processing technology including S1-S4:

[0062] S1 produces the first substrate. For example... Figures 18-a to 18-e As shown, the specific manufacturing process of the first substrate includes: a) taking a plate 1. b) growing a first insulating layer 11 on the plate 1. The first insulating layer 11 can cover the surface of the plate 1. c) growing a metal layer on the first insulating layer 11 and etching the metal layer to form a first metal layer 12. The first metal layer 12 corresponds to the position of the detection post 7 and is used to extract the signal from the detection post 7. At the same time, the first metal layer 12 is also located at the edge of the first insulating layer 11 for bonding the micromirror structure 10. d) growing an insulating layer on the first metal layer 12 and etching the insulating layer to obtain a second insulating layer 13. The shape of the second insulating layer 13 is consistent with the shape of the second substrate 5, and the portion covering the first metal layer 12 is etched on the second insulating layer 13, so that the portion of the first metal layer 12 corresponding to the position of the detection post 7 is exposed to the air. e) growing a metal layer on the second insulating layer 13 and etching the metal layer to obtain a second metal layer 14. The shape of the second metal layer 14 is consistent with the shape of the second insulating layer 13, and the portion of the first insulating layer 11 covered by the second metal layer 14 is etched to make the second metal layer 14 and the first metal layer 12 conductive.

[0063] S2 bonds the second substrate 5 to the first substrate. For example... Figure 18-f As shown, specifically, the second substrate 5 is bonded to the second metal layer 14.

[0064] S3 etches the detection pillar structure on the second substrate 5, such as Figure 18-g As shown.

[0065] S4 bonds the micromirror structure 10 to the first substrate, such as Figure 18-h As shown, specifically, the micromirror structure 10 is bonded to the first metal layer 12 to obtain the micromirror.

[0066] In summary, this invention provides a micromirror with a diaphragm deflection angle threshold detection structure and its fabrication process. This micromirror, by setting different dielectric constants, lateral cross-sectional areas, or heights of the detection pillars in different detection pillar ring groups, can find, according to the capacitance formula C = εSd, that at a certain point, the capacitance between each detection pillar ring group and the micromirror is equal, thus obtaining the capacitance threshold. This allows for the determination of the micromirror's deflection angle threshold θ. Because different dielectric constants, lateral cross-sectional areas, or heights of the detection pillars in each detection pillar ring group create a difference, a more stable threshold capacitance is provided, which is more stable than measuring absolute capacitance. It allows for completely differential detection output, accurately detecting the micromirror's deflection angle threshold θ, which is beneficial for improving control accuracy. The bonding between the first substrate, the second substrate, and the micromirror structure is highly consistent.

[0067] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A micromirror with a diaphragm deflection angle threshold detection structure, characterized in that... The micromirror comprises: The first substrate is used to mount the micromirror structure; The second substrate is bonded to the first substrate, and the second substrate is located on one side of the first substrate; A detection post structure forming a differential capacitance is disposed inside the second substrate, the detection post structure being formed by etching on the second substrate; and An electrode sheet is disposed on the detection column structure, and the electrode sheet is located between the detection column structure and the micromirror structure.

2. The micromirror according to claim 1, characterized in that, The first substrate includes: plate body; A first insulating layer is disposed on the plate body; A first metal layer, disposed on the first insulating layer, is used for electrical conduction with the detection column structure and for bonding the micromirror structure; and The second insulating layer is disposed on the first metal layer.

3. The micromirror according to claim 2, characterized in that, The first substrate further includes a second metal layer, which is located on the second insulating layer and is used to bond the second substrate.

4. The micromirror according to claim 1, characterized in that, The detection column structure includes N detection column ring groups, and the center points of the N detection column ring groups coincide.

5. The micromirror according to claim 4, characterized in that, The detection column ring group includes M detection columns, and the M detection columns are centrally symmetrical.

6. The micromirror according to claim 5, characterized in that, The detection column ring assembly further includes a dielectric layer located at one end of the detection column and between the detection column and the electrode sheet.

7. The micromirror according to claim 1, characterized in that, The micromirror also includes a micromirror structure, which is mounted on the first substrate and embedded in the second substrate.

8. A fabrication process for a micromirror according to any one of claims 1-7, characterized in that, The processing technology includes: Producing the first substrate; The second substrate is bonded to the first substrate; Etching the detection pillar structure on the first substrate; and The micromirror structure is bonded to the first substrate to obtain the micromirror.

9. The micromirror processing technology according to claim 8, characterized in that, The manufacturing process of the first substrate includes: Take a piece of plate; A first insulating layer is grown on the plate. A metal layer is grown on the first insulating layer, and the first metal layer is etched to obtain the first metal layer; An insulating layer is grown on the first metal layer, and a second insulating layer is etched to expose the first metal layer to air; and A metal layer is grown on the second insulating layer and etched to obtain a second metal layer, the second metal layer being used to bond the second substrate.

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