阅读说明：本技术 Mems振动式陀螺仪结构及其制造方法 (MEMS vibrating gyroscope structure and manufacturing method thereof ) 是由 李磬 于 2020-06-28 设计创作，主要内容包括：本发明公开了一种MEMS振动式陀螺仪及其制造方法,属于MEMS陀螺仪传感器设计和加工领域,其技术方案要点是包括盖板硅片、结构硅片和衬底硅片,盖板硅片、结构硅片和衬底硅片自上而下逐层布置组成带有真空腔体的结构,所述结构硅片上安装有器件,所述器件包括两个质量块、四个驱动框、四个检测框、若干弹性连接梁和锚点,本发明的优点在于采用真空键合的方法实现了对器件的真空封装,方法简单且高效,提高了器件成品率,降低了器件制备的成本,适用于批量生产,生产的陀螺仪可有效抑制误差,提高器件的精度和性能。(The invention discloses an MEMS vibration type gyroscope and a manufacturing method thereof, belonging to the field of design and processing of MEMS gyroscope sensors.)

1. A MEMS vibratory gyroscope, comprising: the structure with the vacuum cavity comprises a cover plate silicon wafer (10), a structure silicon wafer (9) and a substrate silicon wafer (6), wherein the cover plate silicon wafer (10), the structure silicon wafer (9) and the substrate silicon wafer (6) are arranged layer by layer from top to bottom to form the structure with the vacuum cavity, a device is arranged on the structure silicon wafer (9), the device comprises two mass blocks (1), four driving frames (2), four detection frames (3), a plurality of elastic connecting beams (5), anchor points (4), driving electrodes, detection electrodes (3a) and functional electrodes (21), the two mass blocks (1) are symmetrically arranged left and right, the two mass blocks (1) are connected through a pair of elastic connecting beams (5), the elastic connecting beams (5) on the periphery of the mass blocks (1) are connected to the anchor points (4) on the periphery, and are fixed on the structure silicon wafer (9) through; the driving frame (2) and the detection frame (3) are connected with the mass block (1) through elastic beams, the outer sides of the driving frame (2) and the detection frame (3) are respectively connected to anchor points (4) through the elastic beams, and are fixed on a structural silicon wafer (9) through the anchor points (4); the driving electrode is positioned in the area of the driving frame (2), the detection electrode (3a) is positioned in the area of the detection frame (3), the functional electrode (21) is positioned in the driving frame (2) or other positions, and the driving electrode, the detection electrode (3a) and the functional electrode (21) are composed of a movable electrode and a fixed electrode; except the anchor point (4) and the fixed electrode, the whole structure of the gyroscope is a suspended movable structure.

2. A MEMS vibratory gyroscope according to claim 1, wherein: the mass block (1) is a polygonal cylinder formed by splicing a plurality of cuboids.

3. A MEMS vibratory gyroscope according to claim 1, wherein: the functional electrode (21) is one or more of a drive detection electrode (2b), a frequency tuning electrode, and an orthogonal compensation electrode (2 a).

4. A MEMS vibratory gyroscope according to claim 1, wherein: the driving electrode, the detection electrode (3a) and the functional electrode (21) are all comb-tooth-shaped electrodes.

5. A MEMS vibratory gyroscope according to claim 1, wherein: the elastic connecting beam (5) is a U-shaped beam, a folding beam or a crab leg beam.

6. A MEMS vibratory gyroscope according to claim 1, wherein: the driving frame (2) and the detection frame (3) are respectively positioned around the two mass blocks (1) and are symmetrically arranged at the central axis.

7. A MEMS vibratory gyroscope according to claim 1, wherein: the elastic connecting beams (5) between the driving frame (2) and the mass block (1) are symmetrically distributed or positioned at the symmetrical axis of the driving frame (2), the number of the elastic connecting beams (5) is one or more, the elastic connecting beams (5) between the driving frame (2) and the anchor points (4) are positioned at the two ends of the driving frame (2) and symmetrically arranged or positioned at the symmetrical axis of the driving frame (2), and the number of the elastic connecting beams (5) is one or more; the elastic connecting beams (5) between the detection frame (3) and the mass block (1) are symmetrically distributed or positioned at the symmetrical axis of the detection frame (3), the number of the elastic connecting beams (5) is one or more, the elastic connecting beams (5) between the detection frame (3) and the anchor point (4) are symmetrically arranged at two ends of the detection frame (3) or positioned at the symmetrical axis of the detection frame (3), and the number of the elastic connecting beams (5) is one or more.

8. A method of manufacturing a MEMS vibratory gyroscope according to any of claims 1 to 7, characterized by: the method comprises the following steps:

s1, providing a substrate silicon wafer (6), and etching a cavity structure with a support pillar (7) on the front surface of the substrate silicon wafer (6) by adopting a deep reactive ion etching method on the substrate silicon wafer (6);

s2, depositing a layer of silicon oxide on the front surface and the back surface of the substrate silicon wafer (6) by adopting a thermal oxidation or chemical vapor deposition method;

s3, providing a structural silicon wafer (9), mounting a device on the structural silicon wafer (9), taking the structural silicon wafer (9) as a gyroscope device layer, and aligning and bonding the structural silicon wafer (9) and the front side of a substrate silicon wafer (6) by adopting a wafer-level vacuum bonding technology;

s4, carrying out patterned photoetching and etching on the structural silicon wafer (9) to etch out the structure of the gyroscope;

s5, preparing a cover plate silicon wafer (10), etching a cavity structure on the front surface of the cover plate silicon wafer (10), and depositing a silicon oxide layer (8) on the front surface of the cover plate silicon wafer (10) by a thermal oxidation or vapor deposition method;

s6, carrying out wafer-level alignment bonding on the front surface of the cover plate silicon wafer (10) and the other side of the structural silicon wafer (9);

s7, etching an electrode lead-out through hole (11) on the back of the cover plate silicon wafer (10) by wet etching or deep reactive ion etching, and depositing a silicon oxide layer (8) on the whole back;

s8, etching off the silicon oxide layer (8) at the position of the electrode lead-out through hole (11);

s9, depositing a metal layer (12) on the cover plate silicon wafer (10), patterning the metal layer (12), completing electrical wiring, manufacturing a metal pad, and realizing wafer-level vacuum packaging of the device while completing the structure of the MEMS gyroscope device.

9. The method of claim 8, wherein: in the steps S1 and S5, the size of the concave cavity structure of the substrate silicon chip (6) and the size of the concave cavity structure of the cover silicon chip (10) are larger than the size of the suspended movable part of the gyroscope.

10. The method of claim 8, wherein: the substrate silicon wafer (6), the structural silicon wafer (9) and the cover silicon wafer (10) are monocrystalline silicon or polycrystalline silicon, wherein the metal layer (12) of the cover silicon wafer (10) is made of one of aluminum, gold, platinum, molybdenum and polycrystalline silicon.

Technical Field

The invention relates to the field of design and processing of MEMS (micro-electromechanical systems) gyroscope sensors, in particular to an MEMS vibrating gyroscope structure and a manufacturing method thereof.

Background

The gyroscope is a sensor for measuring the rotation angle or angular displacement of an object, is used for realizing the measurement and control of the attitude and the track of a motion carrier, and is one of basic core devices of an inertial navigation and guidance system. Compared with the traditional mechanical and optical gyroscopes, the Micro-electro-mechanical System (MEMS) gyroscope has the advantages of low cost, small volume, low power consumption, capability of being integrated with a circuit and the like, is widely applied to the fields of consumer electronics, medical electronics, automotive electronics, aerospace, military and the like, and has great development potential and commercial value. The principle of the MEMS gyroscope is the Coriolis effect, the suspended movable microstructure can be acted by Coriolis force when the platform rotates, and the rotation angular velocity or the rotation angle of the platform can be obtained by measuring a Coriolis force signal. MEMS gyroscopes are mainly classified into capacitive gyroscopes, piezoresistive gyroscopes, piezoelectric gyroscopes, optical gyroscopes, and the like according to detection modes. Among them, the gyroscope using electrostatic driving capacitance detection is widely used commercially, mainly because its structure and working mode are compatible with silicon micromachining technology, and device fabrication and circuit integration are relatively simple.

Although MEMS gyroscopes have numerous advantages and are increasingly used in various fields, the precision of MEMS gyroscopes is still low, the tolerance capability of the current photolithography and micromachining techniques is insufficient compared to the requirement of high-performance inertial sensors, and there are two main ways to reduce the error of MEMS gyroscopes: the method is characterized in that a design sensitive structure is improved or a structural innovation design is provided. And secondly, errors are restrained and compensated, and the performance of the micro gyroscope can be improved through a proper error restraining and circuit compensation control method. The geometrical shape and the material performance of the MEMS gyroscope can be influenced by processing defects and processing errors, and the resonant frequency of the gyroscope is changed; simultaneous manufacturing defects and tolerances cause an imbalance in the gyroscope microstructure, resulting in mechanical interference and quadrature coupling errors between modes that tend to be much larger than coriolis motions; in addition, non-ideal factors such as structural stress and mechanical noise exist in the working process of the device, which seriously influences the precision and stability of the MEMS gyroscope. Therefore, to improve the performance and stability of commercial MEMS gyroscopes, errors must be effectively eliminated.

Disclosure of Invention

The invention aims to provide an MEMS vibration type gyroscope structure and a manufacturing method thereof, wherein a vacuum bonding method is adopted to realize vacuum packaging of devices, the method is simple and efficient, the yield of the devices is improved, the preparation cost of the devices is reduced, the MEMS vibration type gyroscope structure is suitable for batch production, and the produced gyroscope can effectively inhibit errors and improve the precision and the performance of the devices.

The technical purpose of the invention is realized by the following technical scheme:

an MEMS vibration gyroscope comprises a cover plate silicon wafer, a structural silicon wafer and a substrate silicon wafer, wherein the cover plate silicon wafer, the structural silicon wafer and the substrate silicon wafer are arranged layer by layer from top to bottom to form a structure with a vacuum cavity, a device is arranged on the structural silicon wafer and comprises two mass blocks, four driving frames, four detection frames, a plurality of elastic connecting beams, anchor points, driving electrodes, detection electrodes and functional electrodes, the two mass blocks are arranged in bilateral symmetry, the two mass blocks are connected through a pair of elastic connecting beams, and the elastic connecting beams around the mass blocks are connected to the surrounding anchor points and fixed on the structural silicon wafer through the anchor points; the driving frame and the detection frame are connected with the mass block through elastic beams, the outer sides of the driving frame and the detection frame are respectively connected to anchor points through the elastic beams and are fixed on the structural silicon chip through the anchor points; the driving electrode is positioned in the area of the driving frame, the detection electrode is positioned in the area of the detection frame, the functional electrode is positioned in the driving frame or other positions, and the driving electrode, the detection electrode and the functional electrode are composed of a movable electrode and a fixed electrode; except anchor points and fixed electrodes, the whole structure of the gyroscope is a suspended movable structure.

Furthermore, the mass block is a polygonal cylinder formed by splicing a plurality of cuboids.

Further, the functional electrode is one or more of a drive detection electrode, a frequency tuning electrode, and a quadrature compensation electrode.

Furthermore, the driving electrode, the detecting electrode and the functional electrode are all comb-tooth-shaped electrodes.

Further, the elastic connecting beam is a U-shaped beam, a folding beam or a crab-leg beam.

Furthermore, the driving frame and the detection frame are respectively positioned around the two mass blocks and are symmetrically arranged at the central axis.

Furthermore, the elastic connecting beams between the driving frame and the mass block are symmetrically distributed or positioned at the symmetrical axis of the driving frame, the number of the elastic connecting beams is one or more, the elastic connecting beams between the driving frame and the anchor point are symmetrically arranged at the two ends of the driving frame or positioned at the symmetrical axis of the driving frame, and the number of the elastic connecting beams is one or more; the elastic connecting beams between the detection frame and the mass block are symmetrically distributed with the symmetry axis of the detection frame or are positioned at the symmetry axis, the number of the elastic connecting beams is one or more, the elastic connecting beams between the detection frame and the anchor point are symmetrically arranged at two ends of the detection frame or are positioned at the symmetry axis of the detection frame, and the number of the elastic connecting beams is one or more.

A method of manufacturing a MEMS vibratory gyroscope, comprising the steps of:

s1, providing a substrate silicon wafer, and etching a cavity structure with a support pillar on the front surface of the substrate silicon wafer by adopting a deep reactive ion etching method;

s2, depositing a silicon oxide layer on the front and back of the substrate silicon wafer by thermal oxidation or chemical vapor deposition;

s3, providing a structural silicon wafer, mounting a device on the structural silicon wafer, taking the structural silicon wafer as a gyroscope device layer, and aligning and bonding the structural silicon wafer and the front surface of a substrate silicon wafer by adopting a wafer-level vacuum bonding technology;

s4, carrying out patterned photoetching and etching on the structural silicon wafer to etch the structure of the gyroscope;

s5, preparing a cover plate silicon wafer, etching a cavity structure on the front surface of the cover plate silicon wafer, and depositing a layer of silicon oxide on the front surface of the cover plate silicon wafer by a thermal oxidation or vapor deposition method;

s6, carrying out wafer level alignment bonding on the front surface of the cover plate silicon wafer and the other side of the structural silicon wafer;

s7, etching an electrode lead-out through hole on the back of the cover plate silicon wafer by wet etching or deep reactive ion etching, and depositing a silicon oxide layer on the whole back;

s8, etching off the silicon oxide layer at the position of the electrode lead-out through hole;

s9, depositing a metal layer on the cover plate silicon chip, patterning the metal layer to complete electrical wiring, manufacturing a metal pad, and realizing wafer-level vacuum packaging of the device while completing the MEMS gyroscope device structure.

Further, in step S1 and step S5, the size of the cavity structure of the substrate silicon wafer and the size of the cavity structure of the cover silicon wafer are larger than the size of the suspended movable part of the gyroscope.

Further, the substrate silicon wafer, the structural silicon wafer and the cover silicon wafer are monocrystalline silicon or polycrystalline silicon, wherein the metal layer material of the cover silicon wafer is one of aluminum, gold, platinum, molybdenum and polycrystalline silicon.

In conclusion, the invention has the following beneficial effects:

1. the structure of the invention adopts a completely symmetrical double-mass-block tuning-fork type decoupling structure, can realize differential detection, can enhance the output signal of the gyroscope and effectively reduce the output signal error caused by external acceleration and vibration;

2. by using the larger central mass block, mechanical noise generated in work can be well inhibited, and noise errors in output signals can be reduced; functional electrodes can be flexibly distributed in a driving frame region in the gyroscope structure, and the driving frame region comprises a driving detection electrode, a frequency tuning electrode and an orthogonal compensation electrode, so that frequency drift and orthogonal coupling errors caused by machining tolerance and material defects can be reduced, and the precision and the performance of the gyroscope can be effectively improved;

3. the wafer-level vacuum bonding method is used for realizing vacuum sealing of the device, effectively reducing the difficulty of device design, preparation and electrical wiring, is simple and efficient, improves the yield of the device while ensuring the performance of the device, reduces the preparation cost of the device, and is suitable for batch production.

Drawings

Fig. 1 is a schematic plan view of a MEMS vibratory gyroscope according to embodiment 1;

FIG. 2 is a schematic diagram of a MEMS vibratory gyroscope used to embody drive signal and sense signal directions;

FIG. 3-1 is a schematic view of a structure of a substrate silicon wafer with cavities and support posts;

FIG. 3-2 is a schematic structural diagram of a wafer level bonding structure of a structural silicon wafer and a substrate silicon wafer;

3-3 are schematic structural diagrams of a substrate silicon wafer and a structural silicon wafer after patterned lithography and etching;

3-4 are schematic diagrams of a cover plate silicon wafer with a cavity structure and a structural silicon wafer bonded vacuum packaging structure;

3-5 are schematic diagrams of structures of cover plate silicon wafer etched with electrode lead-out through holes and deposited oxide layers;

FIGS. 3-6 are schematic structural diagrams of a structured silicon wafer with surface oxide layers etched away;

3-7 are cross-sectional views of the gyroscope structure after a layer of metal is deposited on the surface of the silicon wafer of the cover plate;

fig. 4 is a schematic plan view of the MEMS vibratory gyroscope according to embodiment 2.

In the figure, 1, a mass block; 2. a drive frame; 21. a functional electrode; 2a, an orthogonal compensation electrode; 2b, driving the detection electrode; 3. detecting a frame; 3a, a detection electrode; 4. an anchor point; 5. an elastic connection beam; 6. a substrate silicon wafer; 7. a support pillar; 8. a silicon oxide layer; 9. a structured silicon wafer; 10. a cover plate silicon wafer; 11. an electrode lead-out through hole; 12. a metal layer.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

In which like parts are designated by like reference numerals. It should be noted that the terms "front," "back," "left," "right," "upper" and "lower" used in the following description refer to directions in the drawings, and the terms "bottom" and "top," "inner" and "outer" refer to directions toward and away from, respectively, the geometric center of a particular component.