Fabry-Perot cavity based on MEMS and packaging method

Abstract

A MEMS-based Fabry-Perot cavity disclosed by the present invention comprises an electrostatic driver and an FP cavity, the electrostatic driver comprises a substrate layer, a buried oxide layer and a device layer, the device layer comprises an outer frame, fixed comb teeth, an inner frame and movable comb teeth, and the fixed comb teeth and the movable comb teeth are provided with electrodes and can be connected with an external control circuit. Comb tooth capacitance is formed between the fixed comb teeth and the movable comb teeth; the FP cavity comprises a first panel and a second panel which are arranged in parallel. The electrostatic driver is driven in a comb tooth mode, accurate driving and control over the relative position of the FP cavity can be achieved, the distance between two parallel panels of the FP cavity is changed by applying voltage to the FP cavity, position detection is achieved by detecting comb tooth capacitance, and then distance control over the two parallel panels of the FP cavity is achieved. And through an advanced packaging technology, the lead-out of the electrode and the packaging of various atmospheres or vacuum environments are realized, and the practicability of the FP cavity is improved.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromechanical technology, and in particular to a MEMS-based Fabry-Perot cavity and a packaging method thereof. Background Art

[0002] Infrared spectroscopy is a reliable and stable analysis method. Microelectromechanical systems (MEMS) Fabry-Perot (FP) tunable filters are core components of instruments such as infrared spectrometers, mobile phone cameras, portable hyperspectral imagers, and remote sensing instruments. Traditional infrared analysis systems and spectrometers are large in size, high in power consumption, and expensive, making them difficult to apply to miniaturized devices. Compared with traditional types of filters, MEMS FP tunable filters have the advantages of small size, high resolution, easy integration, and low power consumption, and therefore play an important role in spectral detection.

[0003] At present, traditional filters are large in size, high in cost, and difficult to integrate. In order to meet the development needs of miniaturization, portability, and low power consumption in spectral detection, the MEMS-based Fabry-Perot cavity has the characteristics of low power consumption, small size, and high precision. It meets the development needs of miniaturization, low power consumption, and portability in spectral detection. Therefore, the MEMS-based Fabry-Perot cavity has become a hot spot in recent development. However, the current MEMS-based Fabry-Perot cavity is mainly driven by electrostatic plate capacitors, piezoelectric drives, and thermal drives, and has problems such as complex structural design and low control accuracy. Summary of the invention

[0004] The purpose of the present invention is to provide a MEMS-based Fabry-Perot cavity and a packaging method thereof to solve the problems existing in the above-mentioned related technologies, improve the control accuracy of the MEMS-based Fabry-Perot cavity, and at the same time simplify the overall structure, realize sensor miniaturization, and improve the adaptability of the sensor.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a MEMS-based Fabry-Perot cavity, comprising:

[0007] An electrostatic driver, the electrostatic driver comprising a base layer, a buried oxide layer and a device layer arranged in sequence from bottom to top, the device layer comprising a fixed unit and a movable unit, the fixed unit comprising an outer frame and fixed comb teeth, the outer frame being an annular structure, the fixed comb teeth being arranged on the inner wall of the outer frame, the movable unit comprising an inner frame and movable comb teeth, the inner frame being an annular structure and being arranged in the outer frame, the movable comb teeth being arranged on the outer wall of the inner frame, the fixed comb teeth and the movable comb teeth being both cantilever structures, the movable comb teeth extending into between two adjacent fixed comb teeth with a gap therebetween, the fixed comb teeth and the movable comb teeth both having electrodes and being able to be connected to an external control circuit to form a comb tooth capacitance between the fixed comb teeth and the movable comb teeth;

[0008] The FP cavity comprises a first panel and a second panel which are arranged in parallel, wherein the first panel is located on top of the second panel with a gap therebetween, and the first panel is connected to the device layer of the electrostatic driver.

[0009] Preferably, the movable unit also includes a support beam, one end of which is connected to the inner frame, and the other end of which extends in a direction away from the inner frame and is connected to the moving comb-tooth electrode; the outer frame has a mounting position matching the support beam and the moving comb-tooth electrode, and there is a gap between the support beam and the moving comb-tooth electrode and the outer frame.

[0010] Preferably, one end of the support beam away from the inner frame extends out from the outer frame, and one end of the support beam extending out of the outer frame is connected to a cross beam.

[0011] Preferably, the outer frame and the inner frame are both rectangular frames, the fixed comb teeth are evenly arranged on the inner wall of the outer frame to form a rectangle, and the movable comb teeth are evenly arranged on the outer wall of the inner frame to form a rectangle.

[0012] Preferably, the height of the fixed comb teeth is 40 μm, the thickness of the movable comb teeth is 50 μm, and the spacing between the fixed comb teeth and the movable comb teeth is 4 μm;

[0013] In a plane parallel to the height directions of the fixed comb teeth and the movable comb teeth, the length of the overlapping portion of the projections of the fixed comb teeth and the movable comb teeth is 200 μm.

[0014] Preferably, the FP cavity further comprises a supporting column and a CMOS substrate, and the second panel is fixed on the CMOS substrate by using the supporting column.

[0015] Preferably, the first panel and the second panel are both rectangular plate structures, the number of the support columns is four, and the support columns are arranged at the four bottom corners of the second panel.

[0016] Preferably, the distance between the first panel and the second panel ranges from 1 μm to 20 μm, and the first panel and the second panel are both made of quartz material.

[0017] Preferably, the MEMS-based Fabry-Perot cavity further includes a packaging structure, which includes a multi-layer main packaging layer and a sealing glass. The multi-layer main packaging layers are stacked in sequence to construct a packaging cavity. The electrostatic driver and the FP cavity are both arranged in the packaging cavity. The sealing glass is arranged on the top of the multi-layer main packaging layer to seal the packaging cavity. The main packaging layer is made of a low-temperature co-fired ceramic material.

[0018] The present invention also provides a packaging method for the above-mentioned MEMS-based Fabry-Perot cavity, wherein the main packaging layer is prepared by stacking, pressing and sintering, and then the electrostatic driver and the FP cavity are fixed in the packaging cavity by photocuring, and the opening of the packaging cavity is sealed by the sealing glass.

[0019] Compared with the related art, the present invention has achieved the following technical effects: the MEMS-based Fabry-Perot cavity of the present invention includes an electrostatic driver and an FP cavity, wherein the electrostatic driver includes a substrate layer, a buried oxide layer and a device layer arranged in sequence from bottom to top, the device layer includes a fixed unit and a movable unit, the fixed unit includes an outer frame and fixed comb teeth, the outer frame is an annular structure, the fixed comb teeth are arranged on the inner wall of the outer frame, the movable unit includes an inner frame and movable comb teeth, the inner frame is an annular structure and is arranged in the outer frame, the movable comb teeth are arranged on the outer wall of the inner frame, the fixed comb teeth and the movable comb teeth are both cantilever structures, the movable comb teeth extend between two adjacent fixed comb teeth and there is a gap between the two, the fixed comb teeth and the movable comb teeth both have electrodes and can be connected to an external control circuit to form a comb capacitance between the fixed comb teeth and the movable comb teeth; the FP cavity includes a first panel and a second panel arranged in parallel, the first panel is located on the top of the second panel and there is a gap between the two, and the first panel is connected to the device layer of the electrostatic driver.

[0020] The MEMS-based Fabry-Perot cavity of the present invention applies a driving voltage to an electrostatic driver, and under the action of electrostatic attraction, the movable comb teeth are displaced relative to the fixed comb teeth. By controlling the voltage applied between the fixed comb teeth and the movable comb teeth, the moving distance and speed of the movable comb teeth can be accurately controlled, thereby driving the FP cavity connected to the electrostatic driver, adjusting the optical properties of the FP cavity, and ensuring the detection accuracy of the MEMS-based Fabry-Perot cavity through precise movement. The MEMS-based Fabry-Perot cavity of the present invention has a movable unit that uses an internal frame to drive the movable comb teeth to move, and has a compact structure, which is conducive to miniaturization of the overall structure of the MEMS-based Fabry-Perot cavity and improves the adaptability of the MEMS-based Fabry-Perot cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The schematic diagram of the comb movement of the electrostatic actuator;

[0023] Figure 2 It is the principle diagram of comb capacitance detection of electrostatic actuator;

[0024] Figure 3 A schematic structural diagram of an electrostatic actuator of a MEMS-based Fabry-Perot cavity disclosed in an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of simulation analysis of an electrostatic actuator based on a MEMS Fabry-Perot cavity disclosed in an embodiment of the present invention;

[0026] Figure 5 A graph showing the relationship between the displacement of a certain point on the inner frame of the electrostatic actuator of the MEMS-based Fabry-Perot cavity and the driving voltage disclosed in an embodiment of the present invention;

[0027] Figure 6 A schematic diagram of a portion of the structure of a MEMS-based Fabry-Perot cavity disclosed in an embodiment of the present invention;

[0028] Figure 7 A schematic diagram of a portion of the structure of a MEMS-based Fabry-Perot cavity disclosed in an embodiment of the present invention;

[0029] Figure 8 It is a schematic diagram of a method for preparing an electrostatic actuator of a MEMS-based Fabry-Perot cavity disclosed in an embodiment of the present invention.

[0030] In the figure: 100, electrostatic driver;

[0031] 1. Base layer; 2. Buried oxide layer; 3. Device layer; 4. Outer frame; 5. Fixed comb teeth; 6. Inner frame; 7. Movable comb teeth; 8. Support beam; 9. Movable comb tooth electrode; 10. Crossbeam; 11. First panel; 12. Second panel; 13. Support column; 14. CMOS substrate; 15. Main packaging layer; 16. Sealing glass; 17. Kovar alloy; 18. Image sensor; 19. Lead wire. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The purpose of the present invention is to provide a MEMS-based Fabry-Perot cavity and a packaging method thereof to solve the problems existing in the above-mentioned related technologies, improve the control accuracy of the MEMS-based Fabry-Perot cavity, and at the same time simplify the overall structure, realize sensor miniaturization, and improve the adaptability of the sensor.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Embodiment 1

[0036] This embodiment provides a MEMS-based Fabry-Perot cavity, such as Figure 3-Figure 7As shown, it includes an electrostatic driver 100 and an FP cavity, wherein the electrostatic driver 100 includes a base layer 1, a buried oxide layer 2 and a device layer 3 arranged in sequence from bottom to top, the device layer 3 includes a fixed unit and a movable unit, the fixed unit includes an outer frame 4 and fixed comb teeth 5, the outer frame 4 is an annular structure, the fixed comb teeth 5 are arranged on the inner wall of the outer frame 4, the movable unit includes an inner frame 6 and movable comb teeth 7, the inner frame 6 is an annular structure and is arranged in the outer frame 4, the movable comb teeth 7 are arranged on the outer wall of the inner frame 6, the fixed comb teeth 5 and the movable comb teeth 7 are arranged on the outer wall of the inner frame 6, and the fixed comb teeth 5 and the movable comb teeth 7 are arranged on the outer wall of the inner frame 6. The movable comb teeth 7 are all cantilever structures. The movable comb teeth 7 extend between two adjacent fixed comb teeth 5, and there is a gap between the movable comb teeth 7 and the fixed comb teeth 5. The fixed comb teeth 5 and the movable comb teeth 7 have electrodes and can be connected to an external control circuit to form a comb tooth capacitor between the fixed comb teeth 5 and the movable comb teeth 7; the FP cavity includes a first panel 11 and a second panel 12 arranged in parallel, the first panel 11 is located on top of the second panel 12 with a gap between the two, and the first panel 11 is connected to the device layer 3 of the electrostatic driver 100.

[0037] The MEMS-based Fabry-Perot cavity of the present invention applies a driving voltage to the electrostatic driver 100. Under the action of the electrostatic attraction, the movable comb teeth 7 are displaced relative to the fixed comb teeth 5. By controlling the voltage applied between the fixed comb teeth 5 and the movable comb teeth 7, the moving distance and speed of the movable comb teeth 7 can be accurately controlled, thereby driving the FP cavity connected to the electrostatic driver 100, adjusting the optical properties of the FP cavity, and ensuring the detection accuracy of the MEMS-based Fabry-Perot cavity through precise movement. In the MEMS-based Fabry-Perot cavity of the present invention, the movable unit uses the inner frame 6 to drive the movable comb teeth 7 to move, and the structure is compact, which is conducive to the miniaturization of the overall structure of the MEMS-based Fabry-Perot cavity and improves the adaptability of the MEMS-based Fabry-Perot cavity.

[0038] It should be explained here that when the movable comb teeth 7 move, the first panel 11 or the second panel 12 of the FP cavity can be connected to the movable comb teeth 7 according to the specific working conditions, thereby driving the first panel 11 or the second panel 12 to move, so as to achieve the purpose of adjusting the distance between the first panel 11 and the second panel 12, thereby adjusting the optical properties of the FP cavity.

[0039] It should be noted here that:

[0040] (1) Electrostatic actuator 100 displacement mechanism

[0041] The MEMS electrostatic actuator 100 uses electrostatic attraction to achieve driving. Electrostatic driving is very efficient at small sizes (1 μm to 10 μm) and is easy to achieve precise control. Electrostatic comb teeth can be divided into planar comb teeth and vertical comb teeth according to their arrangement. Here, the working principle of the vertical comb teeth is studied as an example.

[0042] The vertical comb drive principle diagram is as follows Figure 1 As shown, the left side is a plane diagram, and the right side is a three-dimensional structure diagram. A partial schematic diagram of one of the micromirror's drivers. Assume that the number of comb teeth is N, the comb tooth overlap length is L, the comb tooth spacing is g, the driving voltage is V, and the electrostatic attraction F in the vertical direction v It can be expressed as:

[0043]

[0044] Where ε is the dielectric constant of air. As can be seen from formula (1), the electrostatic attraction is proportional to the number of comb teeth and the length of comb tooth overlap, inversely proportional to the comb tooth spacing, and proportional to the square of the voltage. In order to increase the electrostatic attraction, the measures generally taken are to increase the number of comb teeth and reduce the comb tooth spacing by optimizing the processing technology. However, too small a comb tooth spacing is also prone to short circuit problems, and a compromise needs to be considered during design.

[0045] (2) Electrostatic actuator 100 displacement sensing mechanism

[0046] For the vertically moving comb structure such as Figure 2 As shown, it can be seen that the movable comb teeth 7 and the fixed comb teeth 5 constitute the comb capacitance C(d), which is a parallel plate capacitor structure, and its overlapping area is a function of the displacement d. Therefore, without considering the edge effect, C(d) can be expressed as:

[0047]

[0048] When d is 0, the overlapping area between the movable comb teeth 7 and the fixed comb teeth 5 is 0; as d increases, the overlapping area gradually increases; when d is greater than the comb teeth thickness t, the overlapping area gradually decreases. Since the displacement of the driver is small, it is difficult to reach a level greater than the comb teeth thickness, so the overlapping area A(d) is:

[0049] A(d)=Ld (3)

[0050] Therefore, the displacement of the driver can be reflected by detecting the comb capacitance.

[0051] The movable unit further includes a support beam 8, one end of which is fixedly connected to the inner frame 6, and the other end of which extends in a direction away from the inner frame 6 and is connected to the movable comb electrode 9; the outer frame 4 has a mounting position matching the support beam 8 and the movable comb electrode 9, and there is a gap between the support beam 8 and the movable comb electrode 9 and the outer frame 4. The electrostatic actuator 100 is provided with the support beam 8 to improve the stability of the fixed comb teeth 5 and the movable comb teeth 7, and at the same time, it can effectively improve the dynamic response characteristics of the electrostatic actuator 100.

[0052] The electrostatic actuator 100 of the present invention is divided into a three-layer structure, including a base layer 1, a buried oxide layer 2 and a device layer 3. Figure 3 As shown, in this specific embodiment, the side length of the middle through hole structure of the inner frame 6 is 11 mm, the movable comb teeth 7 are connected to the inner frame 6 and supported by the support beam 8, and the number, thickness, length and spacing of the fixed comb teeth 5 and the movable comb teeth 7 are determined according to the displacement stroke of the inner frame 6 relative to the outer frame 4. In practical applications, it can be optimized by combining simulation analysis and theoretical calculation.

[0053] In other specific embodiments of the present invention, one end of the support beam 8 away from the inner frame 6 extends out of the outer frame 4, and the end of the support beam 8 extending outside the outer frame 4 is connected to the cross beam 10, such as Figure 4 As shown, a simulation analysis is performed on the electrostatic driver 100 having a beam 10 structure. The long side length of the inner frame 6 is 1664 μm, and there is a through hole in the middle. Support beams 8 and beams 10 are provided to provide support for the inner frame 6 to increase the displacement capacity of the inner frame 6 and improve the adaptability of the electrostatic driver 100.

[0054] It should be noted that the outer frame 4 and the inner frame 6 are both rectangular frames, the fixed comb teeth 5 are evenly arranged on the inner wall of the outer frame 4 and form a rectangle, and the movable comb teeth 7 are evenly arranged on the outer wall of the inner frame 6 and form a rectangle. While ensuring the driving capability of the electrostatic actuator 100, the structure is simple and the assembly is compact, which is conducive to the miniaturization of the MEMS-based Fabry-Perot cavity, thereby improving the adaptability of the MEMS-based Fabry-Perot cavity.

[0055] Among them, the height of the fixed comb teeth 5 is 40μm, the thickness of the movable comb teeth 7 is 50μm, and the spacing between the fixed comb teeth 5 and the movable comb teeth 7 is 4μm; in the plane parallel to the height direction of the fixed comb teeth 5 and the movable comb teeth 7, the length of the overlapping part of the projections of the fixed comb teeth 5 and the movable comb teeth 7 is 200μm.

[0056] Figure 5 This is the relationship between the displacement of the inner frame 6 and the driving voltage under quasi-static driving. It can be seen from the figure that the displacement change is proportional to the square of the voltage. Under a driving voltage of 150V, the displacement of the inner frame 6 reaches 420nm, and the displacement of the inner frame 6 can be precisely controlled by controlling the voltage, which is beneficial to improving the detection accuracy.

[0057] Specifically, the FP cavity further includes a support column 13 and a CMOS substrate 14 , and the second panel 12 is fixed on the CMOS substrate 14 by the support column 13 to ensure the structural stability of the FP cavity and the optical performance of the first panel 11 and the second panel 12 .

[0058] Among them, the first panel 11 and the second panel 12 are both rectangular plate structures, which match the structure of the electrostatic driver 100. There are four support columns 13, and the support columns 13 are arranged at the four corners of the bottom of the second panel 12 to ensure support stability, improve the force uniformity and structural stability of the second panel 12, and ensure the working reliability of the FP cavity.

[0059] In this specific embodiment, the spacing between the first panel 11 and the second panel 12 ranges from 1 μm to 20 μm, and the first panel 11 and the second panel 12 are both made of quartz material; in actual applications, the spacing between the first panel 11 and the second panel 12 can be adjusted according to specific working conditions, and the materials of the first panel 11 and the second panel 12 can be selected to meet different testing requirements.

[0060] The MEMS-based Fabry-Perot cavity of the present invention also includes a packaging structure, see Figure 7 The packaging structure includes a multi-layer main packaging layer 15 and a sealing glass 16. The multi-layer main packaging layer 15 is stacked in sequence to construct a packaging cavity. The electrostatic driver 100 and the FP cavity are both arranged in the packaging cavity. The sealing glass 16 is arranged on the top of the multi-layer main packaging layer 15 to seal the packaging cavity. The main packaging layer 15 is made of low-temperature co-fired ceramic material. In this specific embodiment, the thickness of the main packaging layer 15 ranges from 0.8mm to 6mm, and can be processed by engraving, punching, filling, etc. The low-temperature co-fired ceramic material has excellent high-frequency characteristics, high-density integration, and high reliability, and is an indispensable material for aerospace and military industries.

[0061] Embodiment 2

[0062] This embodiment provides a packaging method of the MEMS-based Fabry-Perot cavity in Embodiment 1, wherein a main packaging layer 15 is prepared by stacking, pressing and sintering, and then the electrostatic driver 100 and the FP cavity are fixed in the packaging cavity by photocuring, and the opening of the packaging cavity is sealed by sealing glass 16.

[0063] Low temperature co-fired ceramics are selected as packaging materials. Low temperature co-fired ceramics is a technology that prints interconnecting conductors, components and circuits on unsintered cast ceramic materials, and laminates and presses the structure together, and then sintered into an integrated ceramic multilayer material. The multilayer main body packaging layer 15 of the present invention is laminated and pressed together, and then sintered into shape.

[0064] The image sensor 18 (taking PGA package as an example) is distributed at the bottom layer of the main body packaging layer 15 and is fixed on the main body packaging layer 15 through PGA. In order to enhance its firmness, the image sensor 18 can be fixed by light curing, and the lead 19 of the image sensor 18 can be led out through the through hole and surface lead 19 on the main body packaging layer 15. Above the image sensor 18 is the lower quartz plate. The spacing between the lower quartz plate and the image sensor 18 can be determined by the thickness of the main body packaging layer 15. If the spacing between the two needs to be adjusted, it can be adjusted by curing agent and solder, or by designing the thickness and number of layers of the main body packaging layer 15. The upper quartz plate is fixed on the electrostatic driver 100, and the electrostatic driver 100 is fixed on the main body packaging layer 15. The distance between the upper quartz plate and the lower quartz plate can be accurately adjusted by the thickness of the main body packaging layer 15. The upper opening is sealed by the sealing glass 16. According to the requirements, the sensor chip can be packaged in a vacuum, air, or nitrogen environment, that is, the packaging cavity is evacuated or filled with protective gas. In order to reduce external interference, the periphery of the main packaging layer 15 is wrapped by Kovar alloy 17, and all leads 19 of the device can be led out from the side or bottom of the main packaging layer 15 to achieve interface interconnection with the external control circuit.

[0065] Embodiment 3

[0066] This embodiment provides a method for preparing the electrostatic actuator 100 in the first embodiment.

[0067] It should be emphasized that the fixed comb teeth 5 and the movable comb teeth 7 of the electrostatic driver 100 can be prepared in a high and low comb tooth preparation manner or an upper and lower double comb tooth preparation manner.

[0068] Specifically, when the high-low comb teeth method is adopted, the following steps are included: (a) preparing an SOI wafer, wherein the device layer 3 is low-resistance silicon; (b) photolithography is used to define the fixed comb teeth 5, and then dry etching is performed, the etching depth is about 3 μm, and then photolithography is performed again, and sputtering and peeling are performed to form a metal electrode. The comb teeth structure is defined again by photolithography, and then the movable comb teeth 7 and the fixed comb teeth 5 are etched; (c) finally, the back cavity is etched.

[0069] When the upper and lower double comb teeth method is adopted, the following steps are included: (a) preparing an SOI wafer, wherein the device layer 3 is low-resistance silicon; (b) PECVD (plasma enhanced chemical vapor deposition) growing silicon oxide as an insulating layer; (c) growing polycrystalline silicon; (d) etching through holes and fixed comb teeth 5 and movable comb teeth 7; (e) preparing electrodes; and (f) etching a back cavity.

[0070] In practical applications, the preparation method of the electrostatic actuator can be selected according to the specific working conditions to meet different needs and enhance the flexible adaptability of the MEMS-based Fabry-Perot cavity.

[0071] The electrostatic driver 100 of the MEMS-based Fabry-Perot cavity of the present invention is driven by a comb-tooth method, which can realize accurate driving and control of the relative position of the FP cavity. By applying a voltage to the FP cavity, the distance between the two parallel panels of the FP cavity is changed, and the position detection is realized by detecting the comb-tooth capacitance, thereby realizing the distance control of the two parallel panels of the FP cavity. Through advanced packaging technology, the electrode is led out and packaged in various atmospheres or vacuum environments, thereby improving the practicality of the FP cavity.

[0072] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A MEMS-based Fabry-Perot cavity, characterized in that: include: An electrostatic driver, the electrostatic driver comprising a base layer, a buried oxide layer and a device layer arranged in sequence from bottom to top, the device layer comprising a fixed unit and a movable unit, the fixed unit comprising an outer frame and fixed comb teeth, the outer frame being an annular structure, the fixed comb teeth being arranged on the inner wall of the outer frame, the movable unit comprising an inner frame and movable comb teeth, the inner frame being an annular structure and being arranged in the outer frame, the movable comb teeth being arranged on the outer wall of the inner frame, the fixed comb teeth and the movable comb teeth being both cantilever structures, the movable comb teeth extending into between two adjacent fixed comb teeth with a gap therebetween, the fixed comb teeth and the movable comb teeth both having electrodes and being able to be connected to an external control circuit to form a comb tooth capacitance between the fixed comb teeth and the movable comb teeth; The FP cavity comprises a first panel and a second panel which are arranged in parallel, wherein the first panel is located on top of the second panel with a gap therebetween, and the first panel is connected to the device layer of the electrostatic driver.

2. The MEMS-based Fabry-Perot cavity according to claim 1, characterized in that: The movable unit also includes a support beam, one end of which is connected to the inner frame, and the other end of which extends in a direction away from the inner frame and is connected to the moving comb-tooth electrode; the outer frame has a mounting position matching the support beam and the moving comb-tooth electrode, and there is a gap between the support beam, the moving comb-tooth electrode and the outer frame.

3. The MEMS-based Fabry-Perot cavity according to claim 2, characterized in that: One end of the support beam away from the inner frame extends out from the outer frame, and one end of the support beam extending out of the outer frame is connected to a cross beam.

4. The MEMS-based Fabry-Perot cavity according to claim 1, characterized in that: The outer frame and the inner frame are both rectangular frames, the fixed comb teeth are evenly arranged on the inner wall of the outer frame and form a rectangle, and the movable comb teeth are evenly arranged on the outer wall of the inner frame and form a rectangle.

5. The MEMS-based Fabry-Perot cavity according to any one of claims 1 to 4, characterized in that: The height of the fixed comb teeth is 40 μm, the thickness of the movable comb teeth is 50 μm, and the spacing between the fixed comb teeth and the movable comb teeth is 4 μm; In a plane parallel to the height directions of the fixed comb teeth and the movable comb teeth, the length of the overlapping portion of the projections of the fixed comb teeth and the movable comb teeth is 200 μm.

6. The MEMS-based Fabry-Perot cavity according to claim 1, characterized in that: The FP cavity further comprises a supporting column and a CMOS substrate, and the second panel is fixed on the CMOS substrate by using the supporting column.

7. The MEMS-based Fabry-Perot cavity according to claim 6, characterized in that: The first panel and the second panel are both rectangular plate structures. The number of the support columns is four, and the support columns are arranged at the four bottom corners of the second panel.

8. The MEMS-based Fabry-Perot cavity according to claim 1, characterized in that: The distance between the first panel and the second panel ranges from 1 μm to 20 μm, and the first panel and the second panel are both made of quartz material.

9. The MEMS-based Fabry-Perot cavity according to claim 1, characterized in that: It also includes a packaging structure, which includes a multi-layer main packaging layer and a sealing glass. The multi-layer main packaging layers are stacked in sequence to construct a packaging cavity. The electrostatic driver and the FP cavity are both arranged in the packaging cavity. The sealing glass is arranged on the top of the multi-layer main packaging layer to seal the packaging cavity. The main packaging layer is made of low-temperature co-fired ceramic material.

10. A packaging method of a MEMS-based Fabry-Perot cavity as claimed in claim 9, characterized in that: The main packaging layer is prepared by stacking, pressing and sintering, and then the electrostatic driver and the FP cavity are fixed in the packaging cavity by photocuring, and the opening of the packaging cavity is sealed by the sealing glass.

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