A single-ended free composite cantilever beam vibration sensor and its preparation method

Abstract

The present invention relates to the technical field of semiconductor devices, and specifically to a single-ended free composite cantilever beam vibration sensor and a preparation method thereof. In order to solve the problem of low sensitivity existing in vibration sensors in the prior art, a new single-ended free composite cantilever beam vibration sensor is provided, which includes a frame, a central mass block, four H-shaped cantilever beams and connecting beams. Each H-shaped cantilever beam is composed of two main beams and a secondary beam. The two main beams of each H-shaped cantilever beam are arranged parallel to the corresponding sides of the central mass block. One end of each connecting beam is perpendicularly connected to the outer side of the middle part of one of the main beams of the corresponding H-shaped cantilever beam, and the other ends of the four connecting beams are respectively connected to the four corners of the central mass block. One ends of the four H-shaped cantilever beams are respectively perpendicularly connected to the four sides of the frame, and functional electrodes are arranged on the main beams. The vibration sensor of the present invention has higher sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and particularly to vibration sensors, specifically a single-ended free composite cantilever beam vibration sensor and a preparation method thereof. Background Art

[0002] With the development of science and technology, society has gradually entered the era of unmanned operation. The development of technologies such as artificial intelligence has also promoted the development and progress of hardware devices, especially sensors. For the state detection and fault diagnosis of intelligent devices, as well as the stability of infrared imaging systems, it is necessary to monitor and analyze the disturbance and vibration signals therein. A large part of the maturity of intelligent devices also comes from the accuracy of the data collected by sensors, and the miniaturized structures and devices under the microelectromechanical system are relatively easy to meet the high-precision requirements of today's intelligentization. As a branch under the microelectromechanical system, vibration sensors are mainly divided into capacitive vibration sensors, piezoresistive vibration sensors, piezoelectric vibration sensors, and optoelectronic vibration sensors according to different energy conversion principles. Among them, piezoelectric vibration sensors are widely used due to their advantages such as wide frequency band, high sensitivity, reliable operation, and light weight.

[0003] The prior art is a vibration sensor as shown in Figure 1 The vibration sensor has a publication number of CN116143062B and a patent name of "H"-type single-crystal thin-film piezoelectric vibration sensor and a preparation method thereof. This vibration sensor has a relatively wide test frequency band, which is beneficial to the detection of vibration signals in harsh environments. However, this vibration sensor still cannot detect micro-vibration signals in the mg magnitude, indicating that the sensitivity of this vibration sensor is still relatively low, and its structure still needs to be improved. Summary of the Invention

[0004] In order to solve the problem of relatively low sensitivity existing in the "H"-type single-crystal thin-film piezoelectric vibration sensor in the prior art, the present invention provides a new single-ended free composite cantilever beam vibration sensor and a preparation method thereof.

[0005] The present invention is implemented by adopting the following technical solutions:

[0006] A single-ended free composite cantilever beam vibration sensor includes a frame, a central mass block, and four cantilever beam groups. The frame, the central mass block, and the four cantilever beam groups are all formed by a silicon-based lithium niobate bonded sheet through MEMS technology. The silicon-based lithium niobate bonded sheet is a SiO 2 film grown on the front side of the Si substrate and then bonded with LiNbO 3It is formed by wafer bonding. Four groups of cantilever beams are respectively arranged around the central mass block. Each group of cantilever beams includes an H-shaped cantilever beam and a connecting beam. Each H-shaped cantilever beam is composed of two main beams arranged in parallel and a secondary beam connecting the two main beams. The two main beams of each H-shaped cantilever beam are arranged parallel to the corresponding sides of the central mass block. One end of each connecting beam is perpendicularly connected to the outer side of the middle part of one of the main beams of the corresponding H-shaped cantilever beam, and the other ends of the four connecting beams are respectively connected to the four corners of the central mass block. One ends of the four H-shaped cantilever beams are respectively perpendicularly connected to the four sides of the frame, and functional electrodes for detecting their vibration signals are arranged on each main beam.

[0007] Furthermore, an integrated first warning electrode is provided at the corresponding corner of each connecting beam and the central mass block. Since the corresponding corners of each connecting beam and the central mass block basically do not deform, in subsequent detection, when the output value of the first warning electrode is large, it indicates that this vibration sensor may be damaged, playing a warning role.

[0008] Furthermore, second warning electrodes are also provided on the four main beams close to the central mass block, and the second warning electrodes are arranged at the ends of the main beams close to the frame. Since the positions where the second warning electrodes are arranged also basically do not deform, in subsequent detection, when the output value of the second warning electrode is large, it indicates that this vibration sensor may be damaged, playing a warning role.

[0009] A preparation method of a single-ended free composite cantilever beam vibration sensor includes the following steps:

[0010] (a) Grow a layer of SiO 2 film on the upper surface of the cleaned Si substrate;

[0011] (b) Place the cleaned LiNbO 3 wafer on the SiO 2 film and perform low-temperature bonding on the two to form a silicon-based lithium niobate bonded sheet;

[0012] (c) Grow a layer of SiO 2 film on the back of the silicon-based lithium niobate bonded sheet to prepare for back etching;

[0013] (d) Spin-coat the front of the silicon-based lithium niobate bonded sheet to form a photoresist;

[0014] (e) Place a mask plate with an alignment mark pattern and a metal electrode (as is well known to those skilled in the art: the functional electrodes, the first warning electrodes, and the second warning electrodes described above all belong to metal electrodes) pattern on the photoresist, and then perform photolithography and development on the spin-coated silicon-based lithium niobate bonded sheet.

[0015] (f) Sputter the lithographed and developed lithium niobate on silicon bonded wafer, and the sputtered metal is chromium / gold;

[0016] (g) Strip the sputtered lithium niobate on silicon bonded wafer to expose the metal electrodes and alignment marks;

[0017] (h) Spin coat the front side of the lithium niobate on silicon bonded wafer again;

[0018] (i) Perform lithography and development on the front side of the lithium niobate on silicon bonded wafer that has been spin coated in step (h);

[0019] (j) Use the IBE process to etch the front side of the lithium niobate on silicon bonded wafer until the patterning of the LiNbO 3 wafer is completed;

[0020] (k) Use the RIE process to etch the front side of the lithium niobate on silicon bonded wafer until the patterning of the SiO 2 film is completed;

[0021] (l) Use the wet etching silicon process to etch and prepare the front sides of four cantilever beam groups and the central mass on the front side of the lithium niobate on silicon bonded wafer;

[0022] (m) Spin coat, lithograph, and develop the back side of the lithium niobate on silicon bonded wafer;

[0023] (n) Use the RIE process to etch the SiO 2 film on the back side of the lithium niobate on silicon bonded wafer;

[0024] (o) Deep silicon etch the back side of the lithium niobate on silicon bonded wafer to release the four cantilever beam groups and the central mass;

[0025] (p) Clean the lithium niobate on silicon bonded wafer after deep silicon etching to complete the preparation of the vibration sensor.

[0026] Further, in step (a), a layer of SiO 2 film grown on the front side of the Si substrate is grown by PECVD method.

[0027] Further, in step (b), the bonding temperature during low-temperature bonding is 80 - 120 °C, the bonding pressure is 1000 N - 3000 N, and annealing is required at a temperature of 120 - 150 °C for 3 h after bonding.

[0028] Further, in step (c), a layer of SiO 2 film grown on the back side of the Si substrate is grown by ICPCVD method.

[0029] Further, in step (d), the photoresist is RDP-2100P, the rotation speed of the spin coater is set to 2000 r / min, and it is pre-baked on a hot plate at 100 °C for 3 min.

[0030] Further, in step (f), magnetron sputtering is used for sputtering. The metal electrodes and alignment marks fabricated during sputtering have a chromium / gold thickness of 10 nm / 50 nm.

[0031] Further, in step (l), the wet etching process for silicon specifically involves placing the lithium niobate on silicon bonded wafer in a TMAH developer solution and heating it in a water bath at 85 °C, such that the etching thickness is 70 μm.

[0032] The beneficial effects of the present invention are as follows: For the vibration sensor described in the present invention, by changing the fulcrum position of the H-shaped cantilever beam, the stress action position of the H-shaped cantilever beam is changed, so that the strain at both ends of the H-shaped cantilever beam is converted into the strain at the center, and further, the vibration sensor has higher signal output and sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present invention and, together with the specification, are used to explain the principles of the present invention.

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 It is a schematic structural diagram of the "H"-shaped single-crystal thin-film piezoelectric vibration sensor described in the prior art;

[0036] Figure 2 It is a schematic structural diagram of the single-ended free composite cantilever beam vibration sensor described in the present invention;

[0037] Figure 3 It is a flowchart of the preparation method of the single-ended free composite cantilever beam vibration sensor described in the present invention;

[0038] Figure 4 It is a cross-sectional displacement curve diagram of the single-ended free composite cantilever beam vibration sensor described in the present invention;

[0039] Figure 5 It is a cross-sectional displacement curve diagram of the "H"-shaped single-crystal thin-film piezoelectric vibration sensor described in the prior art;

[0040] Figure 6Total reaction force diagram of the single-ended free composite cantilever beam vibration sensor described in the present invention under vibration in the Z-axis direction;

[0041] Figure 7 Total reaction force diagram of the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under vibration in the Z-axis direction;

[0042] Figure 8 Sensitivity output comparison diagram of the single-ended free composite cantilever beam vibration sensor described in the present invention and the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under vibration in different acceleration directions of the Z-axis.

[0043] In the figure: 1 - frame, 2 - central mass block, 3 - connecting beam, 4 - main beam, 5 - secondary beam, 6 - functional electrode, 7 - first warning electrode, 8 - second warning electrode. Detailed implementation manners

[0044] In order to be able to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the solution of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0045] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. It should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific situations.

[0046] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all the embodiments.

[0047] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0048] As Figure 2 shown, a single-ended free composite cantilever beam vibration sensor includes a frame 1, a central mass block 2, and four cantilever beam groups. The frame 1, the central mass block 2, and the four cantilever beam groups are all formed by a silicon-based lithium niobate bonding sheet through MEMS technology. The silicon-based lithium niobate bonding sheet is a SiO 2 film grown on the front of the Si substrate and then bonded with LiNbO 3It is formed by wafer bonding. Four groups of cantilever beams are respectively arranged around the central mass block 2. Each group of cantilever beams includes an H-shaped cantilever beam and a connecting beam 3. Each H-shaped cantilever beam is composed of two main beams 4 arranged in parallel and a secondary beam 5 connected between the two main beams 4. The two main beams 4 of each H-shaped cantilever beam are arranged parallel to the corresponding sides of the central mass block 2. One end of each connecting beam 3 is perpendicularly connected to the outer side of the middle part of one of the main beams 4 of the corresponding H-shaped cantilever beam. The other ends of the four connecting beams 3 are respectively connected to the four corners of the central mass block 2. One end parts of the four H-shaped cantilever beams are respectively perpendicularly connected to the four sides of the frame 1. Function electrodes 6 are arranged on each main beam 4.

[0049] During specific implementation, an integrated first warning electrode 7 is provided at the corresponding corner of each connecting beam 3 and the central mass block 2. Since the corresponding corners of each connecting beam 3 and the central mass block 2 basically do not deform, in subsequent detection, when the output value of the first warning electrode 7 is large, it indicates that this vibration sensor may be damaged, playing a warning role.

[0050] During specific implementation, second warning electrodes 8 are also provided on the four main beams 4 close to the central mass block 2. The second warning electrodes 8 are arranged at the ends of the main beams 4 close to the frame 1. Since the positions where the second warning electrodes 8 are arranged basically do not deform, in subsequent detection, when the output value of the second warning electrode is large, it indicates that this vibration sensor may be damaged, playing a warning role.

[0051] As Figure 3 shown, a preparation method of a single-ended free composite cantilever beam vibration sensor includes the following steps:

[0052] (a) Grow a 2-μm SiO 2 film on the front side of the cleaned Si substrate; During specific implementation, the SiO 2 film grown on the front side of the Si substrate is grown by PECVD method; In addition, when cleaning the Si substrate, first perform acid cleaning at an environmental temperature of 150°C, then perform alkali cleaning with hydrogen peroxide and ammonia water, then ultrasonically clean with acetone and absolute ethanol in sequence, and finally ultrasonically clean and rinse the surface impurities and organic substances with deionized water and dry the surface with nitrogen.

[0053] (b) Place the cleaned LiNbO 3 wafer on the SiO 2 film and perform low-temperature bonding on the two to form a silicon-based lithium niobate bonded sheet; During specific implementation, it is also necessary to thin and polish the silicon-based lithium niobate bonded sheet formed in this step to make the LiNbO 3The wafer thickness is 5 μm; in addition, the bonding temperature during low-temperature bonding is 80 - 120 °C, the bonding pressure is 1000 N - 3000 N, and annealing is required at a temperature of 120 - 150 °C for 3 h after bonding; meanwhile, LiNbO 3 When cleaning the wafer, first perform pickling at an ambient temperature of 150 °C, then perform alkali cleaning with hydrogen peroxide and ammonia water, then ultrasonically clean with acetone and absolute ethanol in sequence, and finally ultrasonically clean with deionized water to rinse off surface impurities and organic substances, and dry the surface with nitrogen;

[0054] (c)Grow a 5-μm SiO 2 film on the back of the silicon-based lithium niobate bonded wafer to prepare for back etching; specifically, when implementing, a layer of SiO 2 film grown on the back of the Si substrate is grown by the ICPCVD method;

[0055] (d)Spin coat the front side of the silicon-based lithium niobate bonded wafer to form a photoresist; specifically, when implementing, the photoresist is RDP-2100P, the rotation speed of the spin coater is set to 2000 r / min, and pre-bake for 3 min on a hot plate at 100 °C;

[0056] (e)Place a mask plate with an alignment mark pattern and a metal electrode pattern on the photoresist, and then perform photolithography and development on the spin-coated silicon-based lithium niobate bonded wafer; specifically, when implementing, the photolithography equipment uses an EVG610 photolithography machine, the exposure dose is 200 J / cm 2 ², and then develop after mixing with a volume ratio of HDMS to water of 1:8. After pattern development, use oxygen plasma to remove the remaining bottom glue after development, and finally harden the film on a hot plate at 120 °C for 15 minutes;

[0057] (f)Sputter the silicon-based lithium niobate bonded wafer after photolithography and development, and the sputtered metal is chromium / gold; specifically, when implementing, sputtering is performed by the magnetron sputtering method, and the thickness of the chromium / gold used for the metal electrode and the alignment mark fabricated during sputtering is 10 nm / 50 nm;

[0058] (g)Strip the silicon-based lithium niobate bonded wafer after sputtering to reveal the metal electrode and the alignment mark; the specific operation steps are to place the sputtered silicon-based lithium niobate bonded wafer in a cleaning vessel filled with acetone and soak for 30 min, then ultrasonically clean at low power for 5 min. After the front side completely reveals the shape with the metal electrode and the alignment mark, ultrasonically clean with absolute ethanol and deionized water for 5 min respectively to clean it;

[0059] (h)Spin coat the front side of the silicon-based lithium niobate bonded wafer again;

[0060] (i)Perform photolithography and development on the front side of the silicon-based lithium niobate bonded wafer after spin coating in step (h) again;

[0061] (j) Use the IBE process to etch the front side of the silicon-based lithium niobate bonded wafer until LiNbO 3 The patterning of the wafer is completed;

[0062] (k) Use the RIE process to etch the front side of the silicon-based lithium niobate bonded wafer until SiO 2 The patterning of the film is completed;

[0063] (l) Use the wet etching of silicon process to etch the front side of the silicon-based lithium niobate bonded wafer to prepare the front sides of four cantilever beam groups and the central mass block 2; the wet etching of silicon process specifically places the silicon-based lithium niobate bonded wafer in a TMAH developer and heats it in a water bath at 85 °C so that its etching thickness is 70 μm; wet etching can not only achieve the etching of silicon, but also remove the photoresist on the front side of the silicon-based lithium niobate bonded wafer during wet etching, avoiding the difficulty of removing the glue on it after using the conventional deep silicon etching process, thus affecting the overall performance of the device;

[0064] (m) Spray glue, lithography, and development on the back side of the silicon-based lithium niobate bonded wafer; specifically, when implementing, positive photoresist AZ4620 is sprayed on the back side of the silicon-based lithium niobate bonded wafer by a spray coater for 16 circles, and the spray thickness is 60 μm, and then the lithography process is carried out with an exposure dose of 800 mJ / cm 2 After that, it is developed by mixing the developer AZ400k and water in a volume ratio of 1:3. After the pattern is completely developed, the residual bottom glue is removed by oxygen plasma. After removing the glue, it is baked on a hot plate at 120 °C for 20 min;

[0065] (n) Use the RIE process to etch the SiO on the back side of the silicon-based lithium niobate bonded wafer 2 film with an etching thickness of 2 μm; specifically, when implementing, first bond the front side of the silicon-based lithium niobate bonded wafer with pump oil to avoid the phenomenon of the silicon-based lithium niobate bonded wafer breaking during backside etching, and further improve the overall quality of the vibration sensor;

[0066] (o) Deeply etch the back side of the silicon-based lithium niobate bonded wafer to release the four cantilever beam groups and the central mass block 2;

[0067] (p) Clean the silicon-based lithium niobate bonded wafer after deep silicon etching to complete the preparation of the vibration sensor.

[0068] Specifically, when implementing, the thickness of the Si substrate is 500 μm, and the thickness of the SiO 2 film is 1 - 3 μm, the thicknesses of the central mass block 2, the H-shaped cantilever beam, and the connecting beam are all 60 - 70 μm, the length of the 8 main beams is 5560 μm, the width is 500 μm, the length of the four connecting beams is 1000 μm, the width is 500 μm, and the length of the four secondary beams is 500 μm, the width is 500 μm.

[0069] To verify that the sensitivity of the vibration sensor described in the present invention is greatly improved compared to the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art, the following experimental simulations are carried out:

[0070] Experimental simulation 1: Compare and analyze the cross-sectional displacement curve graphs of the vibration sensor described in the present invention and the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under the same acceleration and the same vibration frequency. As Figure 4 and Figure 5 shown, the displacement of the vibration sensor described in the present invention is significantly 3 to 4 times larger than that of the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under the same acceleration and the same vibration frequency;

[0071] Experimental simulation 2: Compare and analyze the total reaction force graphs of the vibration sensor described in the present invention and the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under the vibration in the Z-axis direction in the simulation of COMSOL software. As Figure 6 、 7 shown, the total reaction force of the vibration sensor described in the present invention is significantly 1 to 2 times larger than that of the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under the vibration in the Z-axis direction;

[0072] Experimental simulation 3: Compare and analyze the schematic diagrams of the output charges of the vibration sensor described in the present invention and the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art under the vibration of the sensor in different acceleration directions of the Z-axis in the COMSOL software simulation. As Figure 8 shown, the sensitivity of the vibration sensor described in the present invention is significantly improved compared to the "H"-type single-crystal thin-film piezoelectric vibration sensor described in the prior art.

[0073] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Although the foregoing embodiments have been described in detail, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A single-ended free composite cantilever beam vibration sensor, characterized in that: The invention comprises a frame (1), a central mass block (2), and four cantilever beam groups. The frame (1), the central mass block (2), and the four cantilever beam groups are all formed by a silicon-based lithium niobate bonding sheet through a MEMS process. The silicon-based lithium niobate bonding sheet is formed by growing a layer of SiO2 film on the front side of a Si substrate and bonding it to a LiNbO3 wafer. The four cantilever beam groups are arranged around the central mass block (2), respectively. Each cantilever beam group comprises an H-shaped cantilever beam and a connecting beam (3). Each H-shaped cantilever beam comprises two parallel main beams (4) and a connecting beam (3). The cantilever beam is composed of a secondary beam (5) connected between two main beams (4), the two main beams (4) of each H-shaped cantilever beam are arranged in parallel with the corresponding sides of the central mass block (2), one end of each connecting beam (3) is vertically connected to the outer side of the middle part of one of the main beams (4) of the corresponding H-shaped cantilever beam, the other ends of the four connecting beams (3) are respectively connected to the four corners of the central mass block (2), one end of the four H-shaped cantilever beams are respectively vertically connected to the four sides of the frame (1), and each main beam (4) is arranged with a functional electrode (6).

2. The single-ended free composite cantilever beam vibration sensor according to claim 1, characterized in that: An integrated first warning electrode (7) is provided on the corresponding corner of each connecting beam (3) and the central mass block (2).

3. The single-ended free composite cantilever beam vibration sensor according to claim 2, characterized in that: The four main beams (4) close to the central mass block (2) are each provided with a second early warning electrode (8), and the second early warning electrode (8) is arranged at an end of the main beam (4) close to the frame (1).

4. The method for preparing a single-ended free composite cantilever beam vibration sensor according to any one of claims 1 to 3, characterized in that: The steps include: (a) A SiO2 film is grown on the surface of the cleaned Si substrate; (b) placing the cleaned LiNbO3 wafer on the SiO2 film and bonding the two at low temperature to form a silicon-based lithium niobate bonding wafer; (c) A layer of SiO2 film is grown on the back of the silicon-based lithium niobate bonding wafer to prepare for back etching; (d) performing photoresist coating on the front side of the silicon-based lithium niobate bonding wafer to form a photoresist; (e) placing a mask having an alignment mark pattern and a metal electrode pattern thereon on the photoresist, and then performing photolithography and development on the silicon-based lithium niobate bonding wafer after the photoresist is applied; (f) sputtering the silicon-based lithium niobate bonding wafer after photolithography and development, wherein the sputtered metal is chromium / gold; (g) peeling off the sputtered silicon-based lithium niobate bonding sheet to reveal the metal electrode and alignment mark; (h) performing bonding again on the front side of the silicon-based lithium niobate bonding sheet; (i) performing photolithography and development again on the front side of the silicon-based lithium niobate bonding sheet after the photoresist coating in step (h); (j) The IBE process is used to etch the front side of the silicon-based lithium niobate bonding wafer until the patterning of the LiNbO3 wafer is completed; (k) The silicon-based lithium niobate bonding wafer is etched frontally using the RIE process until the patterning of the SiO2 film is completed; (l) using a wet silicon etching process to etch and prepare the front surface of the silicon-based lithium niobate bonding sheet to form four cantilever beam groups and the front surface of the central mass block (2); (m) Spraying glue, photolithography and developing on the back side of the silicon-based lithium niobate bonding wafer; (n) Etching the SiO2 film on the back of the silicon-based lithium niobate bonding wafer using RIE process; (o) Deep silicon etching of the back side of the silicon-based lithium niobate bonding sheet to release the four cantilever beam groups and the central mass block (2); (p) Cleaning the silicon-based lithium niobate bonding wafer after deep silicon etching to complete the preparation of the vibration sensor.

5. The method for preparing a single-ended free composite cantilever beam vibration sensor according to claim 4, characterized in that: In step (a), a layer of SiO2 film grown on the front side of the Si substrate is grown by PECVD method.

6. The method for preparing a single-ended free composite cantilever beam vibration sensor according to claim 5, characterized in that: In step (b), the bonding temperature during low temperature bonding is 80-120° C., the bonding pressure is 1000N-3000N, and annealing is required at 120-150° C. for 3 hours after bonding.

7. The method for preparing a single-ended free composite cantilever beam vibration sensor according to claim 6, characterized in that: In step (c), a layer of SiO2 film grown on the back side of the Si substrate is grown by ICPCVD method.

8. The method for preparing a single-ended free composite cantilever beam vibration sensor according to claim 7, characterized in that: In step (d), the photoresist is RDP-2100P, the speed of the coating machine is set to 2000 r / min and the coating is pre-baked on a hot plate at 100° C. for 3 min.

9. The method for preparing a single-ended free composite cantilever beam vibration sensor according to claim 8, characterized in that: In step (f), magnetron sputtering is used for sputtering, and the metal electrodes and alignment marks made by sputtering use chromium / gold with a thickness of 10 nm / 50 nm.

10. The method for preparing a single-ended free composite cantilever beam vibration sensor according to claim 9, characterized in that: In step (l), the wet silicon etching process is specifically to place the silicon-based lithium niobate bonding wafer in a TMAH developer and heat it in a water bath at 85° C. so that the etching thickness is 70 μm.

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