High-sensitivity biaxial silicon micro acceleration sensor and preparation method thereof

Abstract

The invention relates to the field of manufacturing of special instruments for navigation, surveying and mapping, meteorology and ocean, in particular to a high-sensitivity biaxial silicon micro-acceleration sensor and a preparation method thereof, the high-sensitivity biaxial silicon micro-acceleration sensor comprises a cap layer, a sensitive structure layer and a substrate layer, and adopts an all-silicon structure; the sensitive structure layer adopts a variable-spacing comb tooth capacitor structure; the variable-spacing comb tooth capacitor structure is composed of a sensing unit group, and the sensing unit group is used for detecting axial acceleration and comprises a spring beam, an anchor point and a mass frame. Fixed comb teeth are arranged on the anchor points, movable comb teeth are arranged on the mass frame, and comb teeth on the fixed comb teeth and the movable comb teeth are arranged in a crossed mode to form a comb tooth structure. When the mass frame is impacted by acceleration, the spring beam drives the movable comb teeth on the mass frame to generate axial displacement, and the axial acceleration is obtained by measuring the capacitance between the comb teeth; the high-sensitivity biaxial silicon micro acceleration sensor designed by the invention has the characteristics of high precision, high linearity and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of navigation, surveying, meteorology and oceanography special instruments manufacturing, in particular to a high-sensitivity dual-axis silicon micro acceleration sensor and a preparation method thereof. BACKGROUND

[0002] The silicon micro acceleration sensor is manufactured by micro-machining technology based on micro-electro-mechanical system (MEMS) technology, and has the advantages of small size, light weight, low power consumption and high reliability. The capacitive acceleration sensor is the most widely used silicon micro acceleration sensor due to its high precision, low temperature sensitivity, low power consumption and wide dynamic range. The comb tooth capacitive acceleration sensor is particularly common.

[0003] In the prior art, the following technical problems exist:

[0004] 1. The dual-axis acceleration sensor is generally composed of two independent acceleration sensors, and the electrical connection of the two axes is complex.

[0005] 2. The comb tooth structure usually adopts a rectangular structure. When the chip area and the number of comb teeth are constant, increasing the wide gap of the fixed tooth bias structure reduces the comb tooth width, thereby reducing the stiffness and causing the movable comb teeth to easily vibrate synchronously during the movement of the sensor. When the comb tooth stiffness increases, the comb tooth width increases. The wide gap of the fixed tooth bias structure decreases, and the parasitic capacitance increases, thereby reducing the detection capacitance. The fixed chip area makes it difficult to balance the number and spacing of the comb teeth.

[0006] 3. The mass frame structure of the chip is connected to the outer frame through a spring beam, and the anchor point is usually placed outside the mass frame. When the mass frame area is large, the mass frame center will be deformed due to stress, thereby affecting the linearity of the sensor.

[0007] Therefore, there is an urgent need for a high-sensitivity dual-axis silicon micro acceleration sensor. SUMMARY

[0008] Therefore, the present application discloses a high-sensitivity dual-axis silicon micro acceleration sensor and a preparation method thereof to solve the above problems.

[0009] A high-sensitivity dual-axis silicon micro acceleration sensor, comprising: a cap layer, a sensitive structure layer and a substrate layer, characterized in that the cap layer, the sensitive structure layer and the substrate layer adopt a full-silicon structure; the sensitive structure layer adopts a variable-pitch comb tooth capacitive structure.

[0010] The variable-pitch comb tooth capacitive structure is composed of a sensitive unit group, and the sensitive unit group is used for detecting axial acceleration and comprises: a first sensitive unit group and a second sensitive unit group.

[0011] The first sensitive unit group and the second sensitive unit group respectively comprise a spring beam, an anchor point and a mass block; the anchor point is provided with fixed comb teeth, the mass block is provided with movable comb teeth, the fixed comb teeth and the movable comb teeth are arranged in an interlaced manner to form a comb structure; when the mass block is impacted by acceleration, the spring beam drives the movable comb teeth on the mass block to axially displace, so that the spacing of the comb teeth changes, and the axial acceleration is obtained by measuring the capacitance between the comb teeth;

[0012] Further, the comb structure adopts a trapezoidal comb structure, and the shapes of the fixed comb teeth and the movable comb teeth are trapezoidal;

[0013] Further, the anchor point is arranged at the middle of the mass block;

[0014] Further, the first sensitive unit group or the second sensitive unit group is composed of a plurality of sensitive units, and the axial acceleration detected by the sensitive units is output after being differentiated;

[0015] Further, the first sensitive unit group and the second sensitive unit group share a group of anchor points;

[0016] A preparation method of a high-sensitivity dual-axis silicon micro acceleration sensor, comprising: preparing a cap layer, preparing a sensitive structure layer, preparing a substrate layer, and obtaining a high-sensitivity dual-axis silicon micro acceleration sensor;

[0017] The preparation of the cap layer comprises:

[0018] S11: using a double-side polished silicon wafer as the cap layer, and performing standard cleaning;

[0019] S12: forming an electrode via by wet etching on the front side;

[0020] S13: etching on the back side to form an anchor point structure;

[0021] S14: removing the surface oxide layer of the cap layer by wet etching;

[0022] S15: growing an oxide layer on the surface of the cap layer by thermal oxidation;

[0023] The preparation of the sensitive structure layer comprises:

[0024] S21: using a double-side polished SOI silicon wafer as the sensitive structure layer, and performing standard cleaning to obtain a sensitive structure layer SOI substrate layer;

[0025] S22: performing anchor point silicon-silicon bonding between the sensitive structure layer SOI substrate layer and the cap layer;

[0026] S23: thinning the sensitive structure layer SOI substrate layer by using a CMP process; and using KOH or TMAH wet etching to etch the remaining silicon on the sensitive structure layer SOI substrate layer to expose the oxide layer of the SOI silicon wafer;

[0027] S24: a pattern etching mask of the device is obtained by photoetching and etching, a DRIE is used to etch the sensitive structure layer SOI substrate layer, and a comb structure is obtained;

[0028] S25: the surface oxide layer of the sensitive structure layer is removed;

[0029] The preparation of the substrate layer comprises:

[0030] S31: a single crystal silicon double-polished wafer is used as the substrate layer, and standard cleaning is performed;

[0031] S32: back etching is performed to form a substrate groove;

[0032] S33: silicon-silicon low-temperature bonding is performed on the substrate layer and the sensitive structure layer;

[0033] Further, a metal lead is formed by sputtering metal in the cap layer electrode via hole and an ohmic contact is formed with the sensitive structure layer, and the preparation is completed.

[0034] The beneficial effects of the present application include:

[0035] A dual-axis acceleration sensor structure is designed, so that the silicon micro acceleration sensor can simultaneously measure the acceleration in different directions;

[0036] A variable-pitch comb tooth capacitance structure is designed, which solves the problem of the synchronous vibration of the movable comb teeth affecting the stability of the sensor during the movement of the sensor by using trapezoidal comb teeth, increases the comb tooth width to improve the comb tooth stiffness, so that the comb teeth do not deform with the movement of the mass block, and at the same time ensures the comb tooth stiffness, increases the wide gap of the fixed tooth bias structure, and does not reduce the number of comb teeth, reduces the parasitic capacitance, improves the detection capacitance, and improves the sensitivity of the sensor;

[0037] A built-in anchor point structure is designed, which effectively suppresses the center deformation of the mass block in the traditional scheme, reduces the zero point drift of the sensor, and improves the linearity of the sensor;

[0038] A dual-axis differential output structure is used to reduce the measurement error and temperature drift of the sensor, and to improve the linearity and sensitivity of the sensor;

[0039] A full silicon structure is used to solve the problem of stress deformation caused by the inconsistency of the thermal expansion coefficient, which leads to the linearity problem of the sensor;

[0040] The high-sensitivity dual-axis silicon micro acceleration sensor designed in the present application can simultaneously measure the acceleration in two different axes, and the two axes do not interfere with each other. The anchor point is designed inside the mass block, which effectively suppresses the center deformation of the mass block, reduces the zero point drift of the sensor, and improves the linearity of the sensor. The two sensitive units share the anchor point, which simplifies the signal lead-out of the sensor, and provides a new design idea for those skilled in the art. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the packaging of the high-sensitivity biaxial silicon micro-accelerometer in this application;

[0042] Figure 2 This is a schematic diagram of the cap layer structure in an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of the sensitive structure layer in an embodiment of this application;

[0044] Figure 4 This is a schematic diagram of the substrate layer structure in an embodiment of this application;

[0045] Figure 5 This is a schematic diagram of the structure of the first sensitive unit group in the embodiments of this application;

[0046] Figure 6 This is a schematic diagram of the structure of the second sensitive unit group in the embodiments of this application;

[0047] Figure 7 This is a schematic diagram of the trapezoidal comb tooth structure in the embodiments of this application;

[0048] Figure 8 This is a schematic diagram of the process for preparing the capping layer in an embodiment of this application;

[0049] Figure 9 This is a schematic diagram of the process for preparing the sensitive structural layer in the embodiments of this application;

[0050] Figure 10 This is a schematic diagram of the process for preparing the substrate layer in an embodiment of this application;

[0051] Figure 11 This is a schematic diagram of the high-sensitivity biaxial silicon micro-accelerometer obtained in the embodiments of this application;

[0052] Reference numerals: 1-Electrode through-hole, 2-Bonding ring, 3-First sensitive unit group, 4-Second sensitive unit group, 5-Fixed comb tooth of the first sensitive unit group, 6-Moving comb tooth of the first sensitive unit group, 7-Central connecting beam, 8-Central anchor point, 9-Mass frame of the first sensitive unit group, 10-U-shaped spring beam, 11-Fixed end of the first sensitive unit group, 12-Common anchor point, 13-U-shaped spring beam, 14-Fixed end of the second sensitive unit group, 15-Mass frame of the second sensitive unit group, 16-Fixed comb tooth of the second sensitive unit group, 17-Moving comb tooth of the second sensitive unit group, 18-Substrate groove. Detailed Implementation

[0053] In order to make the purpose, technical scheme, characteristics and advantages of the present application more clear, in order to make the technical personnel in the art better understand the technical scheme of the present application, the present application is further described in detail below in combination with the drawings and examples.

[0054] Embodiment 1:

[0055] The embodiment includes a high-sensitivity dual-axis silicon micro-acceleration sensor, comprising: a cap layer, a sensitive structure layer and a substrate layer, the cap layer, the sensitive structure layer and the substrate layer adopt a full-silicon structure; the sensitive structure layer adopts a variable-pitch comb-tooth capacitor structure; the variable-pitch comb-tooth capacitor structure is composed of a sensitive unit group, the sensitive unit group is used for detecting axial acceleration, and comprises: a first sensitive unit group and a second sensitive unit group; the first sensitive unit group and the second sensitive unit group respectively comprise: a spring beam, an anchor point and a mass block; a fixed comb tooth is arranged on the anchor point, a movable comb tooth is arranged on the mass block, and the comb teeth on the fixed comb tooth and the movable comb tooth are arranged in cross to form a comb structure; when the mass block is impacted by acceleration, the spring beam drives the movable comb tooth on the mass block to axially displace, so that the pitch of the comb tooth changes, and the axial acceleration is obtained by measuring the capacitance between the comb teeth. Specifically, the distance between the movable comb tooth and the fixed comb tooth becomes larger, and the capacitance value becomes smaller; the distance becomes smaller, and the capacitance value becomes larger; the acceleration measurement can be realized by measuring the capacitance change.

[0056] The full-silicon structure is used to solve the stress problem caused by the inconsistent thermal expansion coefficient. The cap layer, the sensitive structure layer and the substrate layer are connected in sequence from top to bottom by bonding; an electrode through hole is arranged on the cap layer, a metal lead is formed by sputtering metal in the electrode through hole and forms ohmic contact with the sensitive structure layer, and the sensor signal is led out through the electrode through hole. The sensor signal is led out through the cap layer through hole, and the cap layer and the substrate layer form a sealed cavity with the sensitive structure layer respectively to ensure the sealing of the chip.

[0057] Specifically, as shown in Figure 2 , Figure 3 , Figure 4 , an electrode through hole 1 is arranged on the cap layer, a bonding ring 2 is arranged on the sensitive structure layer, and a substrate groove 18 is arranged on the substrate layer. The electrode through hole 1-bonding ring 2-substrate groove 18 are connected by bonding to form a high-sensitivity dual-axis silicon micro-acceleration sensor as shown in Figure 1 .

[0058] Further, as shown in Figure 7As shown, the comb structure adopts a trapezoidal comb structure, that is, the shape of the fixed comb and the movable comb is trapezoidal. In the traditional comb structure, due to the small transverse stiffness of the comb, the movable comb is prone to synchronous vibration during the movement of the sensor, which affects the stability of the sensor. The present application designs a trapezoidal comb structure, which increases the comb width to improve the stiffness of the comb, so that the comb is not easy to deform with the movement of the mass. On the other hand, if the comb width is too wide, it will reduce the number of combs in a limited area, greatly reduce the detection capacitance, and cause the sensitivity of the sensor to decrease. The trapezoidal comb structure ensures the stiffness of the comb while increasing the wide gap of the fixed tooth bias structure and does not reduce the number of combs, thereby reducing the parasitic capacitance, increasing the detection capacitance, and improving the sensitivity of the sensor.

[0059] The mass frame structure of the traditional silicon micro acceleration sensor is usually connected to the outer frame through a spring beam, and the anchor point is placed outside the mass frame. When the area of the mass frame is large, the center of the mass frame will deform due to stress. The present application designs the anchor point in the middle of the mass frame, which suppresses the center deformation of the mass frame, reduces the zero drift of the sensor, and improves the linearity of the sensor. As shown, Figure 5 In the present embodiment, the center anchor point 8 of the first sensitive unit group 3 is arranged in the middle of the mass frame 9 of the first sensitive unit group, and the center anchor point 8 is connected to the mass frame 9 of the first sensitive unit group through the center connecting beam 7.

[0060] The first sensitive unit group or the second sensitive unit group is composed of a plurality of sensitive units. The axial acceleration detected by the sensitive units is output after being differentiated, thereby reducing the measurement error and temperature drift of the sensor, and improving the linearity and sensitivity of the sensor.

[0061] Further, the first sensitive unit group and the second sensitive unit group share a group of anchor points. The design of shared anchor points can simplify the signal lead-out of the sensor and solve the signal lead-out problem caused by the design of the double sensitive unit group, as shown, Figure 5 In the present embodiment, the anchor points include the center anchor point 8 and the shared anchor point 12.

[0062] Further, the first sensitive unit group is embedded in the second sensitive unit group.

[0063] Further, the spring beam adopts a back-shaped spring beam or a U-shaped spring beam. The types of spring beams of the first sensitive unit group and the second sensitive unit group can be adjusted, or both can adopt U-shaped or back-shaped. The two types of spring beams are used to reduce the cross-sensitivity of the sensor, as shown, Figure 3 In the present embodiment, the first sensitive unit group adopts a back-shaped spring beam, and the second sensitive unit group adopts a U-shaped spring beam. The embedded structure increases the utilization rate of the chip area.

[0064] Embodiment 2:

[0065] This embodiment includes a high-sensitivity biaxial silicon micro-accelerometer, which differs from Embodiment 1 in that the first and second sensitive unit groups measure axial accelerations in different directions. In this embodiment, as... Figure 3 As shown, the first and second sensitive unit groups measure the axial acceleration along the X and Y axes in the vertical direction, respectively. Specifically:

[0066] When subjected to an impact with acceleration in the X-axis direction, such as Figure 5 As shown, the U-shaped spring beam 10 drives the mass frame 9 of the first sensitive unit group to move in the direction of the sensitive axis. At this time, the distance between the moving comb teeth 6 and the fixed comb teeth 5 of the first sensitive unit group on the mass frame 9 of the first sensitive unit group increases, the capacitance value decreases, and the distance between the comb teeth decreases, the capacitance value increases. Since the stiffness of the U-shaped spring beam 10 in the Y-axis direction is much greater than that in the X-axis direction, it can effectively suppress the displacement of the mass frame 9 of the first sensitive unit group in the Y-axis direction. Acceleration measurement can be achieved by measuring the change in capacitance.

[0067] When subjected to an impact with acceleration in the Y-axis direction, such as Figure 6 As shown, the U-shaped spring beam 13 drives the second sensitive unit mass frame 15 to move towards the sensitive axis. At this time, the distance between the moving comb teeth 17 and the fixed comb teeth 16 of the second sensitive unit mass frame 15 increases, the capacitance value decreases, and the distance between the comb teeth decreases, the capacitance value increases. Since the stiffness of the U-shaped spring beam 13 in the X-axis direction is much greater than that in the Y-axis direction, it can effectively suppress the displacement of the second sensitive unit mass frame 15 in the X-axis direction. Acceleration measurement can be achieved by measuring the change in capacitance.

[0068] Furthermore, such as Figure 5 As shown, in this embodiment, the first sensitive unit group 3 includes left and right comb teeth, as... Figure 6 As shown, in this embodiment, the second sensitive unit group 4 includes upper and lower comb teeth. After capturing acceleration data in two axes, the left and right comb teeth and the upper and lower comb teeth respectively perform differential output to reduce measurement error.

[0069] Example 3:

[0070] This embodiment includes a method for fabricating a high-sensitivity biaxial silicon micro-accelerometer, comprising: fabricating a capping layer, fabricating a sensitive structure layer, and fabricating a substrate layer to obtain the high-sensitivity biaxial silicon micro-accelerometer. Wherein:

[0071] Preparation of capping layer, such as Figure 8 As shown, it includes:

[0072] S11: A double-sided polished silicon wafer is used as the capping layer for standard cleaning.

[0073] S12: Forming electrode via by front side wet etching.

[0074] S13: Forming anchor structure by back side etching.

[0075] S14: Removing surface oxide layer of cap layer by wet etching.

[0076] S15: Growing oxide layer on surface of cap layer by thermal oxidation.

[0077] Preparation of sensitive structure layer, such as shown in Figure 9 , comprising:

[0078] S21: Adopting double-side polished SOI silicon wafer as sensitive structure layer, performing standard cleaning to obtain sensitive structure layer SOI substrate layer. The device layer thickness of the double-side polished SOI silicon wafer is the device design thickness of the sensitive structure layer.

[0079] S22: Silicon-silicon bonding of the sensitive structure layer SOI substrate layer and the cap layer.

[0080] S23: Thinning the sensitive structure layer SOI substrate layer by CMP process; using KOH or TMAH to etch the remaining silicon on the sensitive structure layer SOI substrate layer to expose the oxide layer of the SOI silicon wafer.

[0081] S24: Obtaining the pattern etching mask of the device by lithography and etching; etching the sensitive structure layer SOI substrate layer by DRIE to obtain the comb structure.

[0082] S25: Removing the surface oxide layer of the sensitive structure layer.

[0083] Preparation of substrate layer, such as shown in Figure 10 , comprising:

[0084] S31: Adopting single crystal silicon double-polished wafer as substrate layer, performing standard cleaning.

[0085] S32: Forming substrate groove by back side etching.

[0086] S33: Silicon-silicon low-temperature bonding of the substrate layer and the sensitive structure layer.

[0087] Further, as shown in Figure 11 , the obtained high-sensitivity biaxial silicon micro acceleration sensor comprises: sputtering metal in the cap layer electrode via to form metal lead and form ohmic contact with the sensitive structure layer, and completing the preparation.

[0088] Finally, it should be noted that the above description only describes some embodiments of the present application, and those skilled in the art can make various changes, modifications, replacements and variations to the embodiments without departing from the principles and spirit of the present application. The protection scope of the present application is defined by the appended claims and their equivalents, and the above acts should be covered within the protection scope of the present application.

[0089] In addition, in the above description of the embodiments, unless otherwise explicitly specified and limited, if the terms "upper", "lower", "horizontal", "inner" and the like appear, the indicated orientation or position relationship is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the present application is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, and does not limit or imply that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. If the terms "first", "second" and the like appear, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance. The components shown in the drawings and described in the embodiments can be arranged and designed in various different configurations; if the term "horizontal" appears, it does not mean that the part must be absolutely horizontal, but can be slightly inclined. "Horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined. If the terms "set", "mount", "connected", "connected" appear, they should be understood broadly, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication between the two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

Claims

1. A high-sensitivity biaxial silicon microaccelerometer sensor comprising: The cap layer, the sensitive structure layer and the substrate layer are characterized in that the cap layer, the sensitive structure layer and the substrate layer adopt a full-silicon structure; the sensitive structure layer adopts a variable-interval comb-shaped capacitor structure; The variable-interval comb-shaped capacitor structure is composed of a sensitive unit group, and the sensitive unit group is used for detecting axial acceleration and includes a first sensitive unit group and a second sensitive unit group; The first sensitive unit group and the second sensitive unit group each include a spring beam, an anchor point and a mass block; the anchor point is provided with a fixed comb, the mass block is provided with a movable comb, and the combs on the fixed comb and the movable comb are arranged in a cross shape to form a comb structure; when the mass block is impacted by acceleration, the spring beam drives the movable comb on the mass block to axially displace, so that the interval of the combs changes, and the axial acceleration is obtained by measuring the capacitance between the combs; The comb structure adopts a trapezoidal comb structure, and the shapes of the fixed comb and the movable comb are trapezoidal.

2. The high-sensitivity biaxial silicon microaccelerometer according to claim 1, characterized in that, The anchor point is arranged in the middle of the mass block.

3. The high-sensitivity biaxial silicon micro acceleration sensor according to claim 1, characterized in that, The first sensitive unit group or the second sensitive unit group is composed of a plurality of sensitive units, and the axial acceleration detected by the sensitive units is output after being differentiated.

4. The high-sensitivity dual-axis silicon micro- acceleration sensor according to claim 1, characterized in that, The first sensitive unit group and the second sensitive unit group share an anchor point group.

5. The high-sensitivity biaxial silicon micro- acceleration sensor according to claim 1, characterized in that, The first sensitive unit group is embedded in the second sensitive unit group.

6. The high-sensitivity biaxial silicon micro- acceleration sensor according to claim 1, characterized in that, The spring beam adopts a back-shaped spring beam or a U-shaped spring beam.

7. The high-sensitivity dual-axis silicon micro- acceleration sensor according to claim 1, characterized in that, An electrode through hole is arranged on the cap layer, and a sensor signal is led out through the electrode through hole; the cap layer and the substrate layer form a sealed cavity with the sensitive structure layer respectively.

8. A method for manufacturing a high-sensitivity biaxial silicon micro acceleration sensor, characterized by, A method for preparing the high-sensitivity dual-axis silicon micro acceleration sensor of any one of claims 1-7 comprises: preparing a cap layer, preparing a sensitive structure layer, preparing a substrate layer, and obtaining a high-sensitivity dual-axis silicon micro acceleration sensor; The preparation of the cap layer comprises: S11: using a double-side polished silicon wafer as the cap layer, and performing standard cleaning; S12: forming an electrode through hole by wet etching on the front surface; S13: etching to form an anchor point structure on the back surface; S14: removing the surface oxide layer of the cap layer by wet etching; S15: growing an oxide layer on the surface of the cap layer by thermal oxidation; The preparation of the sensitive structure layer comprises: S21: using a double-side polished SOI silicon wafer as the sensitive structure layer, and performing standard cleaning to obtain a sensitive structure layer SOI substrate layer; S22: performing anchor point silicon-silicon bonding between the sensitive structure layer SOI substrate layer and the cap layer; S23: thinning the sensitive structure layer SOI substrate layer by using a CMP process; and using KOH or TMAH wet etching to expose the oxide layer of the SOI silicon wafer by etching the remaining silicon on the sensitive structure layer SOI substrate layer; S24: obtaining a device pattern etching mask by photolithography and etching, etching the sensitive structure layer SOI substrate layer by using DRIE to obtain a comb structure; S25: removing the surface oxide layer of the sensitive structure layer; The preparation of the substrate layer comprises: S31: using a single-crystal silicon double-polished wafer as the substrate layer, and performing standard cleaning; S32: etching to form a substrate groove on the back surface; S33: performing silicon-silicon low-temperature bonding between the substrate layer and the sensitive structure layer.

9. The method of claim 8, wherein the high-sensitivity biaxial silicon micro acceleration sensor is prepared by the steps of: The device layer thickness of the double-side polished SOI silicon wafer is the device design thickness of the sensitive structure layer. ​ 10. The method of claim 8, wherein the high sensitivity dual-axis silicon micro acceleration sensor is prepared by the steps of: The high-sensitivity double-shaft silicon micro acceleration sensor comprises: forming a metal lead in a cap layer electrode through hole by sputtering metal and forming an ohmic contact with a sensitive structure layer. ​

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