High-sensitivity high-precision centrifugal MEMS gyroscope based on FBAR

Abstract

The present application relates to the field of micro-electro-mechanical system devices, and particularly relates to a high-sensitivity and high-precision centrifugal MEMS gyroscope based on FBAR. The present application solves the problems of low detection sensitivity and low detection precision of the existing MEMS gyroscope. The high-sensitivity and high-precision centrifugal MEMS gyroscope based on FBAR comprises a force-sensitive structure and a detection element. The force-sensitive structure comprises a square fixed frame. The left inner side surface front part, the front inner side surface right part, the right inner side surface back part and the back inner side surface left part of the square fixed frame each extend to be provided with a detection beam. The end surface of the four detection beams each extends to be provided with a square mass block. The detection element comprises four bottom electrode pads, four top electrode pads, four bottom electrode leads, four top electrode leads and four film bulk acoustic resonators. The present application is suitable for industrial control, aerospace, national defense and military, consumer electronics and other fields.

Description

TECHNICAL FIELD

[0001] The application relates to the field of micro-electro-mechanical system devices, and particularly relates to a high-sensitivity high-precision centrifugal MEMS gyroscope based on FBAR. BACKGROUND

[0002] As one of core devices of inertial technology, the MEMS gyroscope plays an important role in industrial control, aerospace, national defense and military, and consumer electronics. However, in actual application, the existing MEMS gyroscope has the following problems: firstly, the existing MEMS gyroscope has low detection sensitivity due to the limitation of the detection element. Secondly, the force-sensitive structure of the existing MEMS gyroscope needs to be driven to work normally, and the vibration in the driving direction often has an impact on the movement in the detection direction, thereby causing the coupling cross interference of the driving on the detection direction, and resulting in low detection precision. Therefore, it is necessary to invent a high-sensitivity high-precision centrifugal MEMS gyroscope based on FBAR to solve the problems of low detection sensitivity and low detection precision of the existing MEMS gyroscope. SUMMARY

[0003] The application provides a high-sensitivity high-precision centrifugal MEMS gyroscope based on FBAR to solve the problems of low detection sensitivity and low detection precision of the existing MEMS gyroscope.

[0004] The application is implemented by adopting the following technical scheme:

[0005] The high-sensitivity high-precision centrifugal MEMS gyroscope based on FBAR comprises a force-sensitive structure and a detection element.

[0006] The force-sensitive structure comprises a square fixed frame.

[0007] The left inner side surface front part, the front inner side surface right part, the right inner side surface rear part and the rear inner side surface left part of the square fixed frame are each extended to be provided with a detection beam, and the four detection beams are rotationally symmetrically distributed around the center line of the square fixed frame; the upper surfaces of the four detection beams are flush with the upper surface of the square fixed frame; and the lower surfaces of the four detection beams are higher than the lower surface of the square fixed frame.

[0008] The end surfaces of the four detection beams are each extended to be provided with a square mass block, and the four square mass blocks are rotationally symmetrically distributed around the center line of the square fixed frame; the upper surfaces of the four square mass blocks are flush with the upper surfaces of the four detection beams one by one; and the lower surfaces of the four square mass blocks are flush with the lower surfaces of the four detection beams one by one.

[0009] The detection element comprises four bottom electrode pads, four top electrode pads, four bottom electrode leads, four top electrode leads, and four film bulk acoustic resonators.

[0010] The four bottom electrode pads are fixed on the upper surface of the square fixing frame, and the four bottom electrode pads are distributed in rotational symmetry around the center line of the square fixing frame;

[0011] The four top electrode pads are fixed on the upper surface of the square fixing frame, and the four top electrode pads are distributed in rotational symmetry around the center line of the square fixing frame;

[0012] The four bottom electrode leads are distributed in rotational symmetry around the center line of the square fixing frame;

[0013] The four top electrode leads are distributed in rotational symmetry around the center line of the square fixing frame;

[0014] The four film bulk acoustic resonators are fixed on the upper surface of the four detection beams in one-to-one correspondence, and the four film bulk acoustic resonators are distributed in rotational symmetry around the center line of the square fixing frame;

[0015] The bottom electrodes of the four film bulk acoustic resonators are connected to the four bottom electrode pads through the four bottom electrode leads in one-to-one correspondence;

[0016] The top electrodes of the four film bulk acoustic resonators are connected to the four top electrode pads through the four top electrode leads in one-to-one correspondence.

[0017] In operation, the four bottom electrode pads and the four top electrode pads are connected to an external radio frequency circuit or an external vector network analyzer. The specific working process is as follows: when there is an angular velocity input, the four square masses are displaced under the action of centrifugal force, and the four detection beams are bent and deformed, thereby causing the four film bulk acoustic resonators to be structurally strained, so that the resonant frequencies of the four film bulk acoustic resonators change. At this time, the external radio frequency circuit or the external vector network analyzer measures the change in the resonant frequency of the four film bulk acoustic resonators in real time, and calculates the input angular velocity in real time according to the measurement results.

[0018] Based on the above process, compared with the existing MEMS gyro, the high sensitivity and high precision centrifugal MEMS gyro based on FBAR has the following advantages: first, the thin film bulk acoustic wave resonator (FBAR) is used as the detection element, which utilizes the characteristic that the resonant frequency of the thin film bulk acoustic wave resonator is very sensitive to the structural strain (because the resonant frequency of the thin film bulk acoustic wave resonator reaches GHz level, so weak structural strain can cause larger resonant frequency change), so that the detection sensitivity is greatly improved. Second, the force sensitive structure of the present application can work normally without being driven, thereby avoiding the influence of the vibration of the driving direction on the movement of the detection direction, thereby avoiding the coupling cross interference of the driving on the detection direction, and further improving the detection precision.

[0019] The present application has reasonable structure, ingenious design, effectively solves the problems of low detection sensitivity and low detection precision of the existing MEMS gyro, and is suitable for industrial control, aerospace, national defense and military, consumer electronics and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the structure diagram of the present application Figure One .

[0021] Figure 2 is the structure diagram of the present application Figure Two .

[0022] Figure 3 is the structure diagram of the piezoelectric oscillation stack of the thin film bulk acoustic wave resonator in the present application.

[0023] In the figure: 101-square fixed frame, 102-detection beam, 103-square mass block, 201-bottom electrode pad, 202-top electrode pad, 203-bottom electrode lead, 204-top electrode lead, 205-thin film bulk acoustic wave resonator. DETAILED DESCRIPTION

[0024] A high sensitivity and high precision centrifugal MEMS gyro based on FBAR, comprising a force sensitive structure and a detection element;

[0025] The force sensitive structure comprises a square fixed frame 101.

[0026] The left inner side front part, the front inner side right part, the right inner side rear part and the rear inner side left part of the square fixed frame 101 are respectively provided with a detection beam 102, and the four detection beams 102 are rotationally symmetrically distributed around the center line of the square fixed frame 101; the upper surfaces of the four detection beams 102 are flush with the upper surface of the square fixed frame 101; the lower surfaces of the four detection beams 102 are higher than the lower surface of the square fixed frame 101;

[0027] The end surfaces of the four detection beams 102 are respectively provided with a square mass block 103, and the four square mass blocks 103 are rotationally symmetrically distributed around the center line of the square fixed frame 101; the upper surfaces of the four square mass blocks 103 are flush with the upper surfaces of the four detection beams 102 one by one; the lower surfaces of the four square mass blocks 103 are flush with the lower surfaces of the four detection beams 102 one by one;

[0028] The detection element includes four bottom electrode pads 201, four top electrode pads 202, four bottom electrode leads 203, four top electrode leads 204 and four thin film bulk acoustic resonators 205;

[0029] The four bottom electrode pads 201 are fixed to the upper surface of the square fixed frame 101, and the four bottom electrode pads 201 are rotationally symmetrically distributed around the center line of the square fixed frame 101;

[0030] The four top electrode pads 202 are fixed to the upper surface of the square fixed frame 101, and the four top electrode pads 202 are rotationally symmetrically distributed around the center line of the square fixed frame 101;

[0031] The four bottom electrode leads 203 are rotationally symmetrically distributed around the center line of the square fixed frame 101;

[0032] The four top electrode leads 204 are rotationally symmetrically distributed around the center line of the square fixed frame 101;

[0033] The four thin film bulk acoustic resonators 205 are fixed to the upper surface of the four detection beams 102 one by one, and the four thin film bulk acoustic resonators 205 are rotationally symmetrically distributed around the center line of the square fixed frame 101;

[0034] The bottom electrodes of the four thin film bulk acoustic resonators 205 are connected to the four bottom electrode pads 201 one by one through the four bottom electrode leads 203;

[0035] The top electrodes of the four thin film bulk acoustic resonators 205 are connected to the four top electrode pads 202 one by one through the four top electrode leads 204.

[0036] The outer edge length of the square fixed frame 101 is 5000-6000 μm, the inner edge length is 3000-4000 μm, and the frame edge width is 500-600 μm; the length of the detection beam 102 is 1000-1500 μm, the width is 150-200 μm, and the thickness is 80-150 μm; the edge length of the square mass block 103 is 300-500 μm, and the thickness is 80-150 μm.

[0037] The force-sensitive structure is prepared in single crystal silicon with a thickness of 450-550 μm.

[0038] The lower surface of the bottom electrode pad 201, the lower surface of the top electrode pad 202, the side surface of the bottom electrode lead 203, and the side surface of the top electrode lead 204 are all coated with a silicon dioxide insulating layer with a thickness of 0.5-1 μm.

[0039] The piezoelectric oscillation stack of the film bulk acoustic resonator 205 is stacked from top to bottom by a top aluminum electrode layer, a zinc oxide piezoelectric layer, a bottom aluminum electrode layer, and an acoustic wave reflection layer; the acoustic wave reflection layer is stacked from top to bottom by a first silicon dioxide layer, a first tungsten layer, a first chromium layer, a second silicon dioxide layer, a second tungsten layer, a second chromium layer, and a third silicon dioxide layer.

[0040] The length of the piezoelectric oscillation stack of the film bulk acoustic resonator 205 is 100-150 μm, and the width is 80-100 μm; the thickness of the top aluminum electrode layer is 0.3-1.2 μm; the thickness of the zinc oxide piezoelectric layer is 1-1.2 μm; the thickness of the bottom aluminum electrode layer is 0.3-1.2 μm; the thickness of the first silicon dioxide layer is 0.4-0.6 μm; the thickness of the first tungsten layer is 0.4-0.6 μm; the thickness of the first chromium layer is 0.05-0.1 μm; the thickness of the second silicon dioxide layer is 0.4-0.6 μm; the thickness of the second tungsten layer is 0.4-0.6 μm; the thickness of the second chromium layer is 0.05-0.1 μm; and the thickness of the third silicon dioxide layer is 0.4-0.6 μm.

[0041] It also includes a glass substrate; the lower surface of the square fixed frame 101 is bonded and fixed to the upper surface of the glass substrate.

[0042] The thickness of the glass substrate is 1500-2500 μm.

[0043] Although the specific embodiments of the present application have been described above, it is understood by those skilled in the art that these are merely illustrative, and the scope of protection of the present application is defined by the appended claims. Those skilled in the art can make various changes or modifications to the embodiments without departing from the principles and the essence of the present application, and such changes and modifications fall within the scope of protection of the present application.

Claims

1. A high-sensitivity high-precision centrifugal MEMS gyroscope based on FBAR, characterized in that: The force sensing structure comprises a square fixed frame (101) and a detection element; The force sensing structure comprises a square fixed frame (101) and a detection element; The left inner side face front part, the front inner side face right part, the right inner side face back part and the back inner side face left part of the square fixed frame (101) are each extended to be provided with a detection beam (102), and the four detection beams (102) are rotationally symmetrically distributed around the center line of the square fixed frame (101); the upper surfaces of the four detection beams (102) are all flush with the upper surface of the square fixed frame (101); the lower surfaces of the four detection beams (102) are all higher than the lower surface of the square fixed frame (101); The end faces of the four detection beams (102) are each extended to be provided with a square mass block (103), and the four square mass blocks (103) are rotationally symmetrically distributed around the center line of the square fixed frame (101); the upper surfaces of the four square mass blocks (103) are all flush with the upper surfaces of the four detection beams (102) in one-to-one correspondence; the lower surfaces of the four square mass blocks (103) are all flush with the lower surfaces of the four detection beams (102) in one-to-one correspondence; The detection element comprises four bottom electrode pads (201), four top electrode pads (202), four bottom electrode leads (203), four top electrode leads (204) and four film bulk acoustic resonators (205); The four bottom electrode pads (201) are all fixed to the upper surface of the square fixed frame (101), and the four bottom electrode pads (201) are rotationally symmetrically distributed around the center line of the square fixed frame (101); The four top electrode pads (202) are all fixed to the upper surface of the square fixed frame (101), and the four top electrode pads (202) are rotationally symmetrically distributed around the center line of the square fixed frame (101); The four bottom electrode leads (203) are rotationally symmetrically distributed around the center line of the square fixed frame (101); The four top electrode leads (204) are rotationally symmetrically distributed around the center line of the square fixed frame (101); The four film bulk acoustic resonators (205) are fixed to the upper surface root parts of the four detection beams (102) in one-to-one correspondence, and the four film bulk acoustic resonators (205) are rotationally symmetrically distributed around the center line of the square fixed frame (101); The bottom electrodes of the four film bulk acoustic resonators (205) are connected with the four bottom electrode pads (201) in one-to-one correspondence through the four bottom electrode leads (203); The top electrodes of the four film bulk acoustic resonators (205) are connected with the four top electrode pads (202) in one-to-one correspondence through the four top electrode leads (204).

2. The high-sensitivity and high-precision centrifugal FBAR-based MEMS gyroscope according to claim 1, characterized in that: The outer side length of the square fixed frame (101) is 5000-6000 μm, the inner side length is 3000-4000 μm, and the frame edge width is 500-600 μm; the length of the detection beam (102) is 1000-1500 μm, the width is 150-200 μm, and the thickness is 80-150 μm; the side length of the square mass block (103) is 300-500 μm, and the thickness is 80-150 μm.

3. The high sensitivity and high precision FBAR-based centrifugal MEMS gyroscope according to claim 1, characterized in that: The force sensing structure is prepared in single crystal silicon with a thickness of 450-550 microns.

4. The high-sensitivity and high-precision FBAR-based centrifugal MEMS gyroscope according to claim 1, characterized in that: The bottom surface of the bottom electrode pad (201), the bottom surface of the top electrode pad (202), the side surface of the bottom electrode lead (203), and the side surface of the top electrode lead (204) are all coated with a silicon dioxide insulation layer with a thickness of 0.5-1 microns.

5. The high sensitivity and high accuracy FBAR-based centrifugal MEMS gyroscope according to claim 1, characterized in that: The piezoelectric oscillation stack of the film bulk acoustic resonator (205) is stacked from top to bottom by a top aluminum electrode layer, a zinc oxide piezoelectric layer, a bottom aluminum electrode layer, and an acoustic wave reflection layer; the acoustic wave reflection layer is stacked from top to bottom by a first silicon dioxide layer, a first tungsten layer, a first chromium layer, a second silicon dioxide layer, a second tungsten layer, a second chromium layer, and a third silicon dioxide layer.

6. The high-sensitivity high-precision centrifugal FBAR-based MEMS gyroscope according to claim 5, characterized in that: The piezoelectric oscillation stack of the film bulk acoustic resonator (205) has a length of 100-150 microns and a width of 80-100 microns; the thickness of the top aluminum electrode layer is 0.3-1.2 microns; the thickness of the zinc oxide piezoelectric layer is 1-1.2 microns; the thickness of the bottom aluminum electrode layer is 0.3-1.2 microns; the thickness of the first silicon dioxide layer is 0.4-0.6 microns; the thickness of the first tungsten layer is 0.4-0.6 microns; the thickness of the first chromium layer is 0.05-0.1 microns; the thickness of the second silicon dioxide layer is 0.4-0.6 microns; the thickness of the second tungsten layer is 0.4-0.6 microns; the thickness of the second chromium layer is 0.05-0.1 microns; and the thickness of the third silicon dioxide layer is 0.4-0.6 microns.

7. The high sensitivity and high accuracy FBAR-based centrifugal MEMS gyroscope according to claim 1, characterized in that: The glass substrate is also included; the lower surface of the square fixed frame (101) is bonded and fixed to the upper surface of the glass substrate.

8. The high-sensitivity high-precision centrifugal FBAR-based MEMS gyroscope according to claim 7, characterized in that: The thickness of the glass substrate is 1500-2500 microns.

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