Composite cantilever beam vibration sensor with free single end and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor devices, in particular to a single-ended free composite cantilever beam vibration sensor and a preparation method thereof. In order to solve the problem that a vibration sensor in the prior art is low in sensitivity, the novel single-end free composite cantilever beam vibration sensor is provided and comprises a frame, a central mass block, four H-shaped cantilever beams and a connecting beam, each H-shaped cantilever beam is composed of two main beams and two auxiliary beams, the two main beams of each H-shaped cantilever beam are arranged in parallel with the corresponding edges of the central mass block, one end of each connecting beam is vertically connected with the outer side of the middle of one main beam of the corresponding H-shaped cantilever beam, and the other ends of the four connecting beams are connected with the four corners of the central mass block respectively. One end parts of the four H-shaped cantilever beams are vertically connected with four edges of the frame respectively, and functional electrodes are arranged on the main beams. The vibration sensor provided by the invention has higher sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a vibration sensor, in particular to 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 unmanned era. The development of technologies such as artificial intelligence has also promoted the development and progress of hardware equipment, especially sensors. For the status detection, fault diagnosis and stability of infrared imaging systems of intelligent devices, 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 sensor data collection, and the miniaturized structures and devices under micro-electromechanical systems can easily meet the high precision requirements of today's intelligence. As a branch of micro-electromechanical systems, vibration sensors are mainly divided into capacitive vibration sensors, piezoresistive vibration sensors, piezoelectric vibration sensors and photoelectric vibration sensors according to different energy conversion principles. Among them, piezoelectric vibration sensors are widely used due to their advantages such as wide bandwidth, high sensitivity, reliable operation and light weight.

[0003] The prior art is as follows Figure 1 The vibration sensor shown has a publication number of CN116143062B and a patent name of "H"-type single crystal thin film piezoelectric vibration sensor and its preparation method. The vibration sensor has a wider test frequency band, which is conducive to the detection of vibration signals in harsh environments. However, the vibration sensor is still unable to detect micro-vibration signals of the mg level, proving that the sensitivity of the vibration sensor is still relatively low and its structure needs to be improved. Summary of the invention

[0004] In order to solve the problem of low sensitivity of 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 achieved by adopting the following technical solutions: A single-ended free composite cantilever beam vibration sensor comprises 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 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 respectively arranged around the central mass block. Each cantilever beam group comprises an H-shaped cantilever beam and a connecting beam. Each H-shaped cantilever beam is composed of two parallel main beams and a secondary beam connected between 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 vertically connected to the outer middle part of one of the main beams of the corresponding H-shaped cantilever beam. The other ends of the four connecting beams are respectively connected to the four corners of the central mass block. One end of the four H-shaped cantilever beams is respectively vertically connected to the four sides of the frame. Each main beam is arranged with a functional electrode for detecting its vibration signal.

[0006] Furthermore, an integrated first warning electrode is provided on the corresponding corners of each connecting beam and the central mass block. Since the corresponding corners of each connecting beam and the central mass block are basically not deformed, in subsequent detection, when the output value of the first warning electrode is large, it indicates that the vibration sensor may be damaged, which plays a warning role.

[0007] Furthermore, the four main beams near the central mass block are also provided with second warning electrodes, which are arranged at the ends of the main beams near the frame. Since the positions where the second warning electrodes are arranged are basically not deformed, in subsequent detection, when the output value of the second warning electrode is large, it indicates that the vibration sensor may be damaged, which plays a warning role.

[0008] A method for preparing a single-ended free composite cantilever beam vibration sensor comprises the following steps: (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 (it is well known to those skilled in the art that the functional electrode, the first warning electrode, and the second warning electrode are all metal electrodes) on the mask on the photoresist, and then performing photolithography and development on the silicon-based lithium niobate bonding wafer after the photoresist is uniformly coated; (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, four cantilever beam groups and the front side of the central mass block are prepared by etching on the front side of the silicon-based lithium niobate bonding sheet; (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 releases the four cantilever beam groups and the central mass block; (p) Cleaning the silicon-based lithium niobate bonding wafer after deep silicon etching to complete the preparation of the vibration sensor.

[0009] Furthermore, in step (a), a layer of SiO2 film grown on the front side of the Si substrate is grown by PECVD method.

[0010] Furthermore, 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.

[0011] Furthermore, in step (c), the SiO2 film grown on the back side of the Si substrate is grown by ICPCVD method.

[0012] Furthermore, 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.

[0013] Furthermore, in step (f), the sputtering is performed by magnetron sputtering, and the metal electrodes and alignment marks produced by the sputtering use chromium / gold with a thickness of 10 nm / 50 nm.

[0014] Furthermore, 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.

[0015] The beneficial effects produced by the present invention are as follows: the vibration sensor described in the present invention changes the stress action position of the H-shaped cantilever beam by changing the fulcrum position of the H-shaped cantilever beam, thereby converting the strain at the two ends of the H-shaped cantilever beam into the strain at the center, thereby making the vibration sensor have higher signal output and sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 It is a structural schematic diagram of an "H" type single crystal thin film piezoelectric vibration sensor described in the prior art; Figure 2 It is a structural schematic diagram of the composite cantilever beam vibration sensor with a single free end according to the present invention; Figure 3 It is a flow chart of the method for preparing the single-ended free composite cantilever beam vibration sensor of the present invention; Figure 4 It is a cross-sectional displacement curve diagram of the composite cantilever beam vibration sensor with a single free end according to the present invention; Figure 5 It is a cross-sectional displacement curve diagram of the “H” type single crystal thin film piezoelectric vibration sensor described in the prior art; Figure 6 It is a total reaction force diagram of the single-end free composite cantilever beam vibration sensor of the present invention under vibration in the Z-axis direction; Figure 7 It is the 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; Figure 8 The figure is a comparison diagram of the sensitivity output 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 vibrations in different acceleration directions of the Z axis.

[0019] 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 DESCRIPTION

[0020] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0021] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0023] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] like Figure 2 As shown, a single-ended free composite cantilever beam vibration sensor 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 respectively arranged around the central mass block 2. Each cantilever beam group comprises an H-shaped cantilever beam and a connecting beam 3. Each H-shaped cantilever beam is composed of two parallel main beams 4 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 vertically connected to the outer 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 is respectively vertically connected to the four sides of the frame 1. A functional electrode 6 is arranged on each main beam 4.

[0025] In specific implementation, an integrated first warning electrode 7 is provided on the corresponding corner of each connecting beam 3 and the central mass block 2. Since the corresponding corner of each connecting beam 3 and the central mass block 2 is basically not deformed, in subsequent detection, when the output value of the first warning electrode 7 is large, it indicates that the vibration sensor may be damaged, which plays a warning role.

[0026] In specific implementation, the four main beams 4 near the central mass block 2 are also provided with second warning electrodes 8, which are arranged at the ends of the main beams 4 near the frame 1. Since the positions where the second warning electrodes 8 are arranged are basically not deformed, in subsequent detection, when the output value of the second warning electrode is large, it indicates that the vibration sensor may be damaged, which plays a warning role.

[0027] like Figure 3 As shown, a method for preparing a single-ended free composite cantilever beam vibration sensor comprises the following steps: (a) A 2 μm SiO2 film is grown on the front side of the cleaned Si substrate; in the specific implementation, the SiO2 film grown on the front side of the Si substrate is grown by PECVD method; in addition, when the Si substrate is cleaned, it is firstly pickled at an ambient temperature of 150°C, then alkaline washed with hydrogen peroxide and ammonia, then ultrasonically cleaned with acetone and anhydrous ethanol in sequence, and finally ultrasonically cleaned with deionized water to flush out surface impurities and organic matter, and the surface is blown dry with nitrogen; (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 sheet; in specific implementation, the silicon-based lithium niobate bonding sheet formed in this step needs to be thinned and polished to make the thickness of the LiNbO3 wafer 5μm; in addition, 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 3h after bonding; at the same time, when cleaning the LiNbO3 wafer, it is first pickled at an ambient temperature of 150°C, then alkaline washed with hydrogen peroxide and ammonia, then ultrasonically cleaned with acetone and anhydrous ethanol in sequence, and finally ultrasonically cleaned with deionized water to rinse surface impurities and organic matter, and the surface is blown dry with nitrogen; (c) growing a 5 μm SiO2 film on the back of the silicon-based lithium niobate bonding wafer to prepare for back etching; in the specific implementation, the SiO2 film grown on the back of the Si substrate is grown by ICPCVD method; (d) performing photoresist coating on the front side of the silicon-based lithium niobate bonding wafer to form a photoresist; in the specific implementation, the photoresist is RDP-2100P, the speed of the coating machine is set to 2000r / min and the coating is pre-baked on a hot plate at 100°C for 3min; (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 photoresist. In the specific implementation, the photolithography equipment is an EVG610 photolithography machine with an exposure dose of 200 J / cm 2 Then, the mixture was developed with a volume ratio of 1:8 between HDMS and water. After the pattern was developed, oxygen plasma was used to remove the residual primer after development. Finally, the film was hardened on a hot plate at 120°C for 15 minutes. (f) sputtering the silicon-based lithium niobate bonding sheet after photolithography and development, wherein the sputtered metal is chromium / gold; in a specific implementation, the sputtering is performed by magnetron sputtering, and the thickness of the metal electrode and alignment mark made by sputtering is 10nm / 50nm using chromium / gold; (g) peeling off the sputtered silicon-based lithium niobate bonding sheet to reveal the metal electrode and the alignment mark; the specific operation steps are to place the sputtered silicon-based lithium niobate bonding sheet in a cleaning vessel filled with acetone for 30 minutes, then perform low-power ultrasonic treatment for 5 minutes, and after the front side of the sheet completely reveals the shape of the metal electrode and the alignment mark, then perform ultrasonic treatment with anhydrous ethanol and deionized water for 5 minutes respectively; (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) The front side of the silicon-based lithium niobate bonding sheet is etched by a wet silicon etching process to prepare four cantilever beam groups and the front side of the central mass block 2; the wet silicon etching process specifically includes placing the silicon-based lithium niobate bonding sheet in a TMAH developer and heating it in a water bath at 85°C to achieve an etching thickness of 70 μm; wet etching can not only achieve silicon etching, but also remove the photoresist on the front side of the silicon-based lithium niobate bonding sheet during wet etching, thereby avoiding the difficulty in removing the photoresist on the front side of the silicon-based lithium niobate bonding sheet after using a conventional deep silicon etching process, thereby affecting the overall performance of the device; (m) Spraying, photolithography, and development on the back of the silicon-based lithium niobate bonding wafer; in the specific implementation, the back of the silicon-based lithium niobate bonding wafer is sprayed with positive photoresist AZ4620 by a spraying machine, spraying 16 times, the spraying thickness is 60μm, and then the photolithography process is carried out, and the exposure dose is 800mJ / cm 2 Then, the developer AZ400k and water were mixed in a volume ratio of 1:3 for development. After the pattern was completely developed, the residual primer was removed with oxygen plasma. After the removal of the primer, the film was hardened on a hot plate at 120°C for 20 minutes. (n) The SiO2 film on the back of the silicon-based lithium niobate bonding sheet is etched by RIE process, and the etching thickness is 2 μm; in the specific implementation, the front of the silicon-based lithium niobate bonding sheet is first bonded by pump oil to avoid the silicon-based lithium niobate bonding sheet from breaking when etching the back side, thereby further improving the overall quality of the vibration sensor; (o) Deep silicon etching of the back side of the silicon-based lithium niobate bonding sheet releases 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.

[0028] During specific implementation, the thickness of the Si substrate is 500μm, the thickness of the SiO2 film is 1-3μm, the thickness of the central mass block 2, the H-shaped cantilever beam, and the connecting beam are all 60-70μm, the length of the eight main beams is 5560μm, and the width is 500μm. The length of the four connecting beams is 1000μm and the width is 500μm. The length of the four secondary beams is 500μm and the width is 500μm.

[0029] In order to verify that the sensitivity of the vibration sensor described in the present invention is greatly improved compared with the "H" type single crystal thin film piezoelectric vibration sensor described in the prior art, the following experimental simulation analysis is performed: Experimental simulation 1: Comparative analysis of the cross-sectional displacement curves of the vibration sensor of 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, such as Figure 4 and Figure 5 As shown, the displacement of the vibration sensor of the present invention is significantly 3 to 4 times greater than that of the "H" type single crystal thin film piezoelectric vibration sensor described in the prior art at the same acceleration and the same vibration frequency; Experimental simulation 2: Comparative analysis of the total reaction force diagram of the vibration sensor of the present invention and the "H" type single crystal thin film piezoelectric vibration sensor in the prior art under Z-axis vibration under the simulation of COMSOL software, as shown in FIG. Figure 6 , 7 As shown, the total reaction force of the vibration sensor of the present invention under vibration in the Z-axis direction is significantly 1 to 2 times greater than that of the "H"-type single crystal thin film piezoelectric vibration sensor described in the prior art; Experimental simulation three: Comparative analysis of the vibration sensor of the present invention and the "H" type single crystal thin film piezoelectric vibration sensor described in the prior art. The schematic diagram of the sensor output charge under vibration in different acceleration directions of the Z axis simulated by COMSOL software is shown in the figure. Figure 8 As shown, the vibration sensor of the present invention has significantly improved sensitivity compared to the "H"-type single crystal thin film piezoelectric vibration sensor described in the prior art.

[0030] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions 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. A method for preparing a single-ended free composite cantilever beam vibration sensor, 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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