Cantilever microbridge tunable infrared filter based on bulk silicon bonding technology and preparation method thereof

Abstract

An electrostatically tuned infrared filter based on a large-area cantilever microbridge process using bulk silicon bonding technology and a preparation method thereof. The moving mirror and the static mirror are independently processed and interconnected using indium to form an electrostatic voltage-driven tunable F-P filter structure. The present invention effectively solves the defects of using sacrificial layer technology, such as limited light transmission area and inability to withstand vacuum and low-temperature impact. The indium bonding process is used to integrate the moving and static mirrors, which can ensure the consistency of the overall bridge surface over a large area (mm size) and uniform stress on the bridge surface. It meets the conditions for use under vacuum and low-temperature impact. It also realizes the filter range tuning function under voltage drive in the medium-wave infrared range. The invention can be used to integrate filters on the surface of refrigerated infrared detectors to obtain a large-scale dynamic filter tuning detection function covering the entire chip area.

Description

Technical Field

[0001] The present invention relates to a core optical element dynamic filter required in the field of infrared spectrum detection integrated chips, and relates to a large-area cantilever microbridge electrostatic tuning infrared filter based on a bulk silicon bonding process and a preparation method thereof. Background Art

[0002] Infrared detection technology boasts advantages such as long range, excellent interference resistance, strong cloud and fog penetration, and 24 / 7 operation. It has been widely used in aerospace remote sensing, military equipment, astronomical exploration, and security monitoring. With global investment in infrared technology and the advancement of its technological advancement, second- and third-generation infrared focal plane detectors have entered widespread use in equipment, with high-end third-generation detectors also gradually becoming commercially available. This is leading to the development of the fourth-generation focal plane technology: on-chip multifunctional intelligent integrated detection (integrating multiple dimensions, including spectrum, polarization, phase, time, and space). Spectral integrated detection, as one of these branches, is a key research area. Traditional infrared detection chips, which rely solely on intensity detection, produce a two-dimensional (x, y) image of a target. This makes it difficult to avoid interference bands and achieve active detection in complex environments, thus failing to meet the requirements for clear target identification in camouflaged or obscured environments. A new generation of infrared spectral integrated detection chips leverages the "fingerprint recognition" properties of the infrared spectrum. Based on intensity detection, they integrate infrared spectral information to perform multi-dimensional spectral detection (x, y, λ) with a single image. This is an effective approach to improving target recognition and immunity to environmental interference. Research on integrated high-performance spectral integrated detection technology, core key technology - dynamic tuning filter.

[0003] In recent years, developed countries, led by the United States and Germany, have vigorously researched this key technology. At present, the main technical route focuses on the suspended microbridge filter solution based on the Fabry-Perot (FP) principle. Under the voltage bias of the upper and lower electrodes, the electrostatic force attracts each other to change the suspension height and adjust the filter cavity length, thereby realizing active selection of the filter. The integrated processing route based on the existing micro-surface sacrificial layer technology has the following defects: on the one hand, due to the special nature of the suspended structure, under the influence of external environment such as temperature and pressure, the upper bridge surface is prone to tilt and bend. Especially when used in vacuum and low-temperature environments, the bridge surface has stress mismatch and other problems, making it difficult to integrate and effectively use in refrigerated infrared detectors; on the other hand, due to the integrated processing of micro-surface devices, the area generally does not exceed the millimeter level and cannot cover the entire infrared focal plane chip. For example, the article "MEMS-based tunable Fabry–Perot filters for adaptive multispectral thermal imaging" (Journal of Microelectromechanical Systems, 2016, 25(1): 227-235.) produced a dynamic filter with an integrated structure based on surface micromachining sacrificial layer technology.

[0004] The prior art has the following technical problems:

[0005] 1. The traditional micro-FP filter made based on surface sacrificial layer technology has a limited effective filtering area, and the area cannot reach the centimeter level;

[0006] 2. The traditional micro FP filter made based on surface sacrificial layer technology has the problem of easy collapse of the cantilever structure in vacuum and low temperature, and cannot be integrated with the refrigerated infrared detector. Summary of the Invention

[0007] In order to overcome the deficiencies of the above-mentioned prior art, improve the stability and balance of the suspended flat plate, and increase the light-transmitting area of ​​the filter to meet the conditions for integrated use with a refrigerated infrared detection chip in a low-temperature vacuum environment, the present invention provides a large-area cantilever microbridge electrostatically tuned infrared filter based on a bulk silicon bonding process and a preparation method thereof. Focusing on the simulation of the coupling of multiple physical fields of force, electricity, and light, the structural mechanics of the structure are studied. First, the structure of the corners and fixed points where the equivalent stress is concentrated is improved, and a circular arc cantilever structure is introduced. The deep silicon etching technology is used to perform integrated processing on the bulk silicon to release the cantilever beam. Secondly, the indium column bonding method is used to obtain an integrated filter sample to ensure the uniform force on the bridge deck and the high consistency of the bridge deck displacement.

[0008] The purpose of the present invention is to provide a large-area cantilever microbridge spectrally tunable filter that can be used in a low-temperature vacuum environment and a preparation method thereof.

[0009] The technical solutions of the present invention are as follows:

[0010] On the one hand, the present invention provides a tunable infrared filter with an arc-shaped cantilever microbridge structure based on bulk silicon bonding technology, comprising a static mirror and a dynamic mirror. The filter is characterized in that the static mirror and the dynamic mirror are interconnected and bonded into one body via indium balls, forming a cavity in the middle, and utilizing electrostatic force to achieve dynamic tunability.

[0011] The static mirror includes a static mirror silicon substrate layer, a gold electrode layer and a static mirror filter area located on the static mirror silicon substrate layer, and a plurality of indium column beams; the gold electrode layer is composed of multiple electrode groups, each electrode group is composed of a first electrode and a second electrode, the first electrode is circular at one end close to the static mirror filter area, and the indium column beam is arranged above it for conducting electricity with the moving mirror T, one end of the second electrode corresponds to the first electrode, and the other end is in an arc shape surrounding the static mirror filter area; the static mirror filter area is circular and is located at the center of the circle formed by the arc ends of the second electrode;

[0012] The moving mirror T includes a moving mirror silicon substrate layer, and a cantilever beam electrode layer and a moving mirror filter area located on the moving mirror silicon substrate layer; the cantilever beam electrode layer is composed of a plurality of arm beam electrode groups with the same number as the electrode groups, and each arm beam electrode group is connected in sequence by a first cantilever beam electrode, a second cantilever beam electrode and a third cantilever beam electrode connected in an arc shape, and the arm beam electrode groups are nested with each other to form a circle, and the moving mirror filter area is circular and located in the center of the circle formed by the arm beam electrode groups; the moving mirror silicon substrate layer is divided into a fixed area, a cantilever beam area and a bridge deck area; the first cantilever beam electrode is located on the cantilever beam area and forms a support structure corresponding to the indium column beam; the second cantilever beam electrode is located on the cantilever beam area, and a part of the third cantilever beam electrode is located on the bridge deck area, and the other part is located on the fixed area.

[0013] Furthermore, the indium column beam is bonded to the first cantilever beam electrode, so that the dynamic and static mirrors are bonded into one; the static mirror filtering area and the dynamic mirror filtering area correspond to each other to form a suspended cavity structure. Under the action of the bias voltage, the electrostatic force is used to reduce the height of the cantilever beam area and the bridge surface, thereby realizing the tuning of the filtering wavelength with the cavity length height.

[0014] Preferably, there are three electrode groups, three indium column beams, and three arm beam electrode groups.

[0015] On the other hand, the present invention also provides a method for preparing the arc-shaped cantilever microbridge structure tunable infrared filter based on bulk silicon bonding technology, which is characterized in that it comprises the following steps:

[0016] Step 1. Still mirror production

[0017] ① Using a photolithography lift-off process on the static mirror silicon substrate layer, a gold bottom electrode layer is formed. The gold electrode layer is composed of multiple electrode groups, each electrode group consists of a first electrode and a second electrode. The electrode groups are arranged in an arc shape and are used to apply an electrostatic bias voltage;

[0018] ② In the middle area of ​​the static mirror silicon substrate layer, the static mirror filter area is grown by magnetron sputtering;

[0019] ③ Growing an indium column beam on the first electrode of the gold bottom electrode layer by a photolithography lift-off process, so as to connect with the electrode of the moving mirror to form a circuit path;

[0020] Step 2. Motion mirror production

[0021] ① A cantilever beam electrode layer is fabricated on the moving mirror silicon substrate layer by a photolithography lift-off process. The cantilever beam electrode layer is composed of multiple arm beam electrode groups with the same number as the electrode groups. Each arm beam electrode group is connected in sequence by a first cantilever beam electrode, a second cantilever beam electrode, and a third cantilever beam electrode connected in an arc shape. The shape and position of the first cantilever beam electrode correspond to the shape and position of the indium column beam. The second cantilever beam electrode corresponds to the cantilever beam region position. The shape and position of the third cantilever beam electrode correspond to the shape and position of the second electrode. The arm beam electrode groups are nested with each other to form a circle.

[0022] ②Grow the moving mirror filter area on the moving mirror silicon substrate layer using magnetron sputtering method;

[0023] ③ Using a deep silicon etching method to etch through the silicon substrate layer of the moving mirror to form a fixed area, a cantilever beam area, and a bridge deck area, wherein the second cantilever beam electrode is located in the cantilever beam area in an overlapping relationship, and one end of the cantilever beam area is connected to the fixed area, and the other end is connected to the bridge deck area;

[0024] Step 3. Bonding

[0025] The indium pillar is bonded to the first cantilever beam electrode, integrating the dynamic and static mirrors, forming a suspended cavity structure in between. Under the action of a bias voltage, the height of the cantilever beam region and the bridge deck can be tuned, changing the height of the cavity structure and thus achieving height-dependent tuning of the filter wavelength.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The arc-shaped microbridge structure of the present invention effectively solves the problems of excessive and concentrated stress in the dynamic tunable filter produced by the prior art based on micro-surface sacrificial layer technology, which leads to structural warping, tilting, and collapse. The dynamic mirror and the static mirror are independently processed and manufactured, and bonded together using indium interconnection to form an electrostatic voltage-driven tunable FP filter structure. The electrodes on the static mirror form a capacitive loop. By applying a polarization voltage, the positive and negative charges at the upper and lower poles are concentrated to produce an attractive displacement, ultimately achieving the purpose of changing the filter's filtering range. This makes the cantilever microbridge structure more stable and can maintain long-term stability in vacuum and low-temperature environments.

[0028] 2. The use of an indium bonding process integrates the dynamic and static mirrors, ensuring uniformity across a large bridge deck area (mm size) and uniform stress across the entire bridge deck. This invention ensures a large filtering area across the entire bridge deck, with a maximum diameter of 5.4mm for the central circular suspended bridge deck. This effectively addresses the limitations of sacrificial layer technology, such as the limited light transmission area.

[0029] 3. It meets the operating conditions of vacuum and low temperature shock. It can be used to integrate filters on the surface of refrigerated infrared detectors to obtain compact on-chip integrated dynamic filter tuning detection functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the arc-shaped cantilever microbridge structure tunable infrared filter based on bulk silicon bonding technology of the present invention.

[0031] Figure 2 It is a side view of the arc-shaped cantilever microbridge structure tunable infrared filter based on the bulk silicon bonding technology of the present invention.

[0032] Figure 3 1 is a schematic structural diagram of an electrode group of a static mirror according to an embodiment of the present invention;

[0033] Figure 4 1 is a schematic structural diagram of an arm beam electrode group of a moving mirror according to an embodiment of the present invention;

[0034] Figure 5 This is a regional division diagram of the moving mirror silicon substrate layer after etching according to an embodiment of the present invention;

[0035] Figure 6 This is a flow chart for preparing a static mirror according to an embodiment of the present invention;

[0036] Figure 7 is a flow chart for preparing a moving mirror according to an embodiment of the present invention;

[0037] Figure 8 Schematic diagram of an embodiment of the present invention wherein a movable mirror and a static mirror are pressed together with a reverse welding bond;

[0038] Figure 92 is a schematic diagram of a state where voltage is applied according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below with reference to the embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0040] An electrostatically tuned filter based on a large-area arc-shaped cantilever microbridge process using bulk silicon bonding technology and a preparation method thereof. The moving mirror and the static mirror are independently processed and manufactured, and finally integrated into one by indium column bonding to form a statically tunable FP filter structure. In this embodiment, the moving mirror adopts a cantilever beam area T4 composed of an arc-shaped cantilever structure to connect the middle bridge surface area T5, and three arc-shaped electrodes are grown on the surface of the silicon cantilever beam. The dynamic, static and static mirrors are bonded into one by aligning the indium column beam with the first cantilever beam electrode T21 solder joint. The first electrode B21 and the second electrode B22 constitute a capacitive circuit of the moving mirror and the static mirror. By applying a polarization voltage, the positive and negative charges at the upper and lower poles are gathered to generate an attractive displacement, thereby achieving the purpose of changing the filtering range of the filter.

[0041] Figure 1 It is a structural schematic diagram of the arc-shaped cantilever microbridge structure tunable infrared filter based on bulk silicon bonding technology of the present invention. Figure 2 This is a side view of the present invention's arc-shaped cantilever microbridge tunable infrared filter using bulk silicon bonding technology. As shown, the filter comprises a static mirror and a dynamic mirror. These mirrors are independently fabricated using bulk silicon processing technology. Finally, they are interconnected using indium pillar flip-flops and bonded together to form a microelectromechanical system (MEMS)—an electrostatically tuned FP filter. The static mirror comprises a static mirror silicon substrate layer B1, a gold electrode layer, a static mirror filter region B3, and an indium pillar beam B4. The dynamic mirror comprises a dynamic mirror silicon substrate layer T1, a cantilever beam electrode layer, and a dynamic mirror filter region T3.

[0042] like Figure 3 As shown, the gold electrode layer is composed of multiple electrode groups, each electrode group is composed of a first electrode B21 and a second electrode B22. The first electrode B21 is circular at one end close to the static mirror filter area B3, and the indium column beam B4 is arranged above it for conducting electricity with the moving mirror T. One end of the second electrode B22 corresponds to the first electrode B21, and the other end is in an arc shape surrounding the static mirror filter area B3; the static mirror filter area B3 is circular and is located in the center of the circle formed by the arc end of the second electrode B22.

[0043] The cantilever beam electrode layer is composed of multiple arm beam electrode groups with the same number as the electrode groups. Each arm beam electrode group is connected in sequence by a first cantilever beam electrode T21, a second cantilever beam electrode T22 and a third cantilever beam electrode T23 to form an arc shape. The arm beam electrode groups are nested with each other to form a circle. The dynamic mirror filter area T3 is circular and is located in the center of the circle formed by the arm beam electrode groups. Figure 4 As shown, the third cantilever electrode T23 overlaps the cantilever region T4, both employing an arc structure. The three indium pillars B4 of the static mirror are aligned and bonded to the first cantilever electrode T21 of the dynamic mirror's flip solder joint. The indium pillars bond the dynamic and static mirrors together, creating a suspended structure at the center.

[0044] The method for preparing the electrostatically tuned filter based on the arc-shaped cantilever microbridge process comprises the following steps:

[0045] (1) Static mirror production, such as Figure 6 shown

[0046] 1) Using a photolithographic lift-off process, a gold bottom electrode layer is formed on the static mirror silicon substrate layer B1. The gold electrode layer is composed of multiple electrode groups, each of which consists of a first electrode B21 and a second electrode B22. The bottom electrode is generally arc-shaped, with the middle area being the filter light-transmitting area; the surrounding area is surrounded by electrodes for applying an electrostatic bias voltage;

[0047] 2) In the middle area of ​​the static mirror silicon substrate layer B1, a static mirror filter area B3 is grown by magnetron sputtering;

[0048] 3) growing an indium column beam B4 on the first electrode B21 of the gold bottom electrode layer by a photolithography lift-off process, for connecting with the electrode of the moving mirror to form a circuit path;

[0049] (2) Moving mirror production, such as Figure 7 shown

[0050] 1) Using a photolithography lift-off process on the moving mirror silicon substrate layer T1, a cantilever beam electrode layer is formed. The cantilever beam electrode layer is composed of multiple groups of arm beam electrode groups with the same number as the electrode groups. Each arm beam electrode group is connected in sequence by a first cantilever beam electrode T21, a second cantilever beam electrode T22, and a third cantilever beam electrode T23 connected in an arc shape. The shape and position of the first cantilever beam electrode T21 correspond to the shape and position of the indium column beam B4. The second cantilever beam electrode 22 corresponds to the cantilever beam area T4. The shape and position of the third cantilever beam electrode T23 correspond to the shape and position of the second electrode B22. The arm beam electrode groups are nested with each other to form a circle.

[0051] 2) growing the filter area T3 on the moving mirror silicon substrate layer T1 by magnetron sputtering;

[0052] 3) Use deep silicon etching to etch through the moving mirror silicon substrate layer T1, releasing the silicon cantilever beam structure area T4. The cantilever beam is distributed in an arc shape, with one end connected to the substrate fixed part and the other end connected to the suspended bridge surface. Three connections are formed with the bridge surface, overlapping with the upper and lower layers of the cantilever beam metal electrode area T23. Figure 5 shown.

[0053] (3) Inverted solder joint pressure, such as Figure 8 shown

[0054] The moving mirror and the static mirror are bonded together by reverse welding, forming a suspended layer in the middle. Under the action of voltage bias, the height of the moving mirror cantilever can be tuned, driving the displacement of the middle filter area to achieve filter tuning.

[0055] Example 1:

[0056] The thickness of Si substrate B1 is 300 μm, and the thickness of T1 is 100 μm.

[0057] The thickness of the Au dynamic mirror and static mirror electrode layer 2 is 150nm;

[0058] The height of the bonded indium column is 2 μm;

[0059] The radius of the Si top circular bridge surface is 2.7 mm;

[0060] Example 2:

[0061] The thickness of Si substrate B1 is 300 μm, and the thickness of T1 is 100 μm.

[0062] The thickness of the Au dynamic mirror and static mirror electrode layer 2 is 150nm;

[0063] The height of the bonded indium column is 2 μm;

[0064] The radius of the circular bridge surface on the Si top is 2.5 mm;

[0065] Example 2

[0066] The thickness of Si substrate B1 is 300 μm, and the thickness of T1 is 100 μm.

[0067] The thickness of the Au dynamic mirror and static mirror electrode layer 2 is 150nm;

[0068] The height of the bonded indium column is 2 μm;

[0069] The radius of the circular bridge surface on the Si top is 2 mm;

[0070] The sample bias voltage is gradually increased from 0V, and the filter peak position moves from the initial 5.2μm to the short wave, and moves to 3.3μm when the bias voltage is 20V. The bonded filter is pasted into the Dewar, and the molecular pump is used to evacuate the vacuum to less than 1×10-3 Pa, then inflate to normal pressure, repeat this cycle several times, and observe whether the sample cantilever structure remains stable. The sample Dewar packaging photo is shown in the figure. Through experimental testing, the vacuum degree is 1×10 -4 Pa, after repeated 5 times of pumping and degassing, it was observed that the cantilever beam structure was still stable and no fracture occurred. The upper moving mirror did not fall off, and the overall condition of the FP filter was good. This proved that the sample had good resistance to vacuum shock. The sample was encapsulated in a dewar, and liquid nitrogen was poured into the dewar after the vacuum was evacuated. The temperature of the dewar was waited for to drop to 77K, and the temperature was maintained for 30 minutes before observing the condition of the sample. Then, after waiting for the temperature to rise to room temperature, liquid nitrogen was refilled to lower the temperature back to 77K. After 5 cycles of the cooling and heating steps, samples were taken to observe the integrity of the sample. After the temperature shock test, the sample remained intact.

[0071] The technical effect of the present invention effectively solves the problems of filter area limitations in traditional micro-surface processing technology, as well as excessive and concentrated stress leading to structural warping, tilting, and collapse. The invention successfully realizes the tunability of the medium-wave infrared filtering range under voltage drive, and the cantilever microbridge structure is more stable and can withstand vacuum and low-temperature impacts. The present invention can ensure a large filtering area for the entire bridge deck, and the maximum diameter of the central circular suspended bridge deck is 5.4mm. The invention can be used for integrated filters on the surface of refrigerated infrared detectors to obtain compact on-chip integrated dynamic filter tuning detection functions.

Claims

1. A tunable infrared filter with an arc-shaped cantilever microbridge structure based on bulk silicon bonding technology, comprising a static mirror and a dynamic mirror, characterized in that: The static mirror and the dynamic mirror are interconnected and bonded into one body through indium balls, forming a cavity in the middle, and realizing dynamic tunability by utilizing electrostatic force; The static mirror comprises a static mirror silicon substrate layer (B1), a gold electrode layer and a static mirror filter area (B3) located on the static mirror silicon substrate layer (B1), and a plurality of indium column beams (B4); the gold electrode layer is composed of a plurality of electrode groups, each electrode group is composed of a first electrode (B21) and a second electrode (B22); the first electrode (B21) is circular at one end close to the static mirror filter area (B3), and the indium column beam (B4) is arranged above it for conducting electricity with the moving mirror T; one end of the second electrode (B22) corresponds to the first electrode (B21), and the other end is in an arc shape surrounding the static mirror filter area (B3); the static mirror filter area (B3) is circular and is located at the center of the circle formed by the arc end of the second electrode (B22); The moving mirror comprises a moving mirror silicon substrate layer (T1), and a cantilever beam electrode layer and a moving mirror filter area (T3) located on the moving mirror silicon substrate layer (T1); the cantilever beam electrode layer is composed of a plurality of arm beam electrode groups with the same number as the electrode groups, each arm beam electrode group is connected in sequence by a first cantilever beam electrode (T21), a second cantilever beam electrode (T22) and a third cantilever beam electrode (T23) connected in an arc shape, and the arm beam electrode groups are nested with each other to form a circle, and the moving mirror filter area (T3) is circular and located in the The center of the circle formed by the arm beam electrode group; the moving mirror silicon substrate layer (T1) is divided into a fixed area, a cantilever beam area (T4) and a bridge surface area (T5); the first cantilever beam electrode (T21) is located on the cantilever beam area (T4) and forms a supporting structure corresponding to the indium column beam (B4); the second cantilever beam electrode (T22) is located on the cantilever beam area (T4); a portion of the third cantilever beam electrode (T23) is located on the bridge surface area (T5) and the other portion is located on the fixed area; The indium column beam (B4) is bonded to the first cantilever beam electrode (T21), so that the moving mirror and the static mirror are bonded into one body; the static mirror filter area (B3) and the moving mirror filter area (T3) correspond to each other to form a suspended cavity structure; under the action of a bias voltage, the height of the cantilever beam area (T4) and the bridge area (T5) is reduced by electrostatic force, thereby achieving tuning of the filtering wavelength with the cavity length height; There are three electrode groups, three indium column beams (B4), and three arm beam electrode groups.

2. A method for preparing the arc-shaped cantilever microbridge structure tunable infrared filter based on bulk silicon bonding technology according to claim 1, characterized in that: The steps include: Step 1. Still mirror production ① Using a photolithography lift-off process on the static mirror silicon substrate layer (B1), a gold electrode layer is formed. The gold electrode layer is composed of multiple electrode groups, each electrode group consists of a first electrode (B21) and a second electrode (B22). The electrode groups are arranged in an arc shape and are used to apply an electrostatic bias voltage; ② In the middle area of ​​the static mirror silicon substrate layer (B1), a static mirror filter area (B3) is grown by magnetron sputtering; ③ growing an indium column beam (B4) on the first electrode (B21) of the gold electrode layer by a photolithography lift-off process, for connecting with the electrode of the moving mirror to form a circuit path; Step 2. Motion mirror production ① A cantilever beam electrode layer is manufactured on a moving mirror silicon substrate layer (T1) by a photolithography stripping process, wherein the cantilever beam electrode layer is composed of a plurality of arm beam electrode groups having the same number as the electrode groups, and each arm beam electrode group is connected in sequence by a first cantilever beam electrode (T21), a second cantilever beam electrode (T22), and a third cantilever beam electrode (T23) connected in an arc shape, wherein the shape and position of the first cantilever beam electrode (T21) correspond to the shape and position of the indium column beam (B4), the position of the second cantilever beam electrode (T22) corresponds to the position of the cantilever beam region (T4), and the shape and position of the third cantilever beam electrode (T23) correspond to the shape and position of the second electrode (B22), and the arm beam electrode groups are nested with each other to form a circle; ②Growing the moving mirror filter area (T3) on the moving mirror silicon substrate layer (T1) by magnetron sputtering; ③ A deep silicon etching method is used to etch through the moving mirror silicon substrate layer (T1) to form a fixed area, a cantilever beam area (T4) and a bridge surface area (T5); the second cantilever beam electrode (T22) is located at the cantilever beam area (T4) in an overlapping relationship, and one end of the cantilever beam area (T4) is connected to the fixed area, and the other end is connected to the bridge surface area (T5); Step 3. Bonding The indium column beam (B4) is bonded to the first cantilever beam electrode (T21), so that the moving mirror and the static mirror are bonded into one body, forming a suspended cavity structure in the middle; under the action of a bias voltage, the height of the cantilever beam area (T4) and the bridge surface area (T5) can be tuned to change the height of the cavity structure, thereby achieving tuning of the filtering wavelength with height.

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