CN112225170A

CN112225170A - MEMS device and forming method thereof

Info

Publication number: CN112225170A
Application number: CN202011433127.4A
Authority: CN
Inventors: 李森科·伊戈尔·叶夫根耶维奇; 徐宝; 徐元; 吴刚
Original assignee: Hangzhou Maixinmin Micro Technology Co Ltd
Current assignee: Hangzhou Maixinmin Micro Technology Co Ltd
Priority date: 2020-12-09
Filing date: 2020-12-09
Publication date: 2021-01-15
Anticipated expiration: 2040-12-09
Also published as: CN112225170B

Abstract

The invention relates to an MEMS device and a forming method thereof, wherein the MEMS device comprises a proof mass block, four groups of sensing combs which are arranged on four sides of the proof mass block respectively, and four groups of driving combs which are arranged on one side, far away from the proof mass block, of the four sensing combs, wherein the four groups of the driving combs are arranged on the four sides of the proof mass block, and the four groups of the driving combs are arranged on one side, far away from the proof mass block, of the four sensing combs in a one-to-one correspondence manner, so that a single device of the MEMS device can sense rotation and acceleration, equivalent functions which can be achieved by at least two MEMS sensors in the related technology are realized, and the production cost is reduced.

Description

MEMS device and forming method thereof

Technical Field

The invention relates to the technical field of micro electro mechanical systems, in particular to an MEMS device and a forming method thereof.

Background

MEMS sensors are widely used in consumer electronics, industrial production, medical electronics, automotive electronics, aerospace, military, and other fields. MEMS sensors have great potential for development and commercial value.

Compared with a mechanical sensor or an optical sensor, the MEMS sensor has advantages of low cost, small volume, low power consumption, and the like, and can be integrated with an integrated circuit, and the MEMS inertial sensor includes an accelerometer capable of sensing acceleration and a gyroscope capable of sensing rotation, which are main components of a navigation system.

The operating principle of MEMS accelerometers is the inertial effect. When the object moves, the suspended microstructure is affected by inertial force. The change in the accelerometer signal is proportional to the linear acceleration.

The operating principle of a MEMS gyroscope is the coriolis effect. When the object is rotated, coriolis forces affect the microstructure of the suspended matter. The change in the gyroscope signal is proportional to the angular velocity or tilt of the object.

MEMS gyroscopes and accelerometers are mainly classified into capacitive, piezoresistive, piezoelectric, and optical types according to the detection method. Meanwhile, the electrostatic driving and capacitive detector is widely applied to MEMS gyroscopes and accelerometers mainly because of the simple structure and the compatibility of the working mode and the semiconductor technology.

MEMS chips can be manufactured by semiconductor fabrication methods and have single or multiple devices. When multiple devices are implemented in a single chip, multiple inertial signals, e.g., rotation and acceleration or acceleration along multiple axes, may be achieved. A six degree of freedom sensing system requires two types of devices (i.e., a gyroscope for sensing rotation and an accelerometer for sensing acceleration). Each class may have a shared device that senses multiple axis information, for example, a single gyroscope senses two or three axis rotation and an accelerometer senses two or three axis acceleration.

In the related art, the MEMS accelerometer cannot sense rotation, and likewise, the MEMS gyroscope cannot sense acceleration.

Disclosure of Invention

It is an object of the present invention to provide a MEMS device that is capable of sensing rotation as well as acceleration.

In order to achieve the purpose, the invention adopts the following technical scheme: a MEMS device, comprising:

a proof mass;

sensing combs which are arranged on four sides of the proof mass respectively, wherein each sensing comb comprises a plurality of movable sensing comb teeth, a first frame integrating a plurality of movable sensing comb teeth, a plurality of fixed sensing comb teeth and a second frame integrating a plurality of fixed sensing comb teeth, the movable sensing comb teeth and the fixed sensing comb teeth are mutually crossed to form an interdigital structure and extend along a direction parallel or approximately parallel to the side length of the proof mass corresponding to the side where the movable sensing comb teeth and the fixed sensing comb teeth are arranged, the fixed sensing comb teeth are fixed on a first substrate, and the first frame is elastically connected with the proof mass;

the drive combs are arranged in four groups, the drive combs are arranged on one side, away from the proof mass block, of the four sensing combs in a one-to-one correspondence mode, each group of the drive combs comprises a plurality of movable drive comb teeth, a third frame integrating a plurality of the movable drive comb teeth, a plurality of fixed drive comb teeth and a fourth frame integrating a plurality of the fixed drive comb teeth, the movable drive comb teeth and the fixed drive comb teeth are mutually crossed to form an interdigital structure and extend along the direction perpendicular to or approximately perpendicular to the side length of the proof mass block corresponding to the side where the movable drive comb teeth and the fixed drive comb teeth are located, the fixed drive comb teeth are fixed on the first substrate, and the third frame is connected with the first frame.

Preferably, the MEMS device further includes the first substrate, and a first sensing plane electrode fixedly disposed on the first substrate, the first sensing plane electrode being disposed below the proof mass.

Preferably, the MEMS device further comprises a first driving planar electrode fixedly disposed on the first substrate, the first driving planar electrode being disposed below the proof mass.

Preferably, the MEMS device further includes a plurality of anchor points, each of the anchor points is fixed to the first substrate, and the first frame and the third frame are elastically connected to one or more of the anchor points.

Preferably, part of the movable drive comb teeth and part of the fixed drive comb teeth form a functional comb, and the rest of the movable drive comb teeth and the rest of the fixed drive comb teeth form one or more compensation combs arranged on the side of the functional comb.

Preferably, the MEMS device further includes a second substrate disposed on a side of the proof mass away from the first substrate, and two ends of the first substrate and the second substrate are connected to form a cavity for placing the proof mass, the sensing comb, the driving comb, the anchor point, the first sensing planar electrode, and the first driving planar electrode.

Preferably, the MEMS device further includes a second sensing planar electrode and a second driving planar electrode disposed on the second substrate, and the first sensing planar electrode and the second sensing planar electrode, the first driving planar electrode, and the second driving planar electrode are disposed opposite to each other.

Preferably, a plurality of through holes are formed in the proof mass block.

The invention also provides a forming method of the MEMS device, which comprises the following steps:

grinding the substrate to a thickness required for forming the MEMS device structure;

and etching the substrate to form a proof mass, a sensing comb, a driving comb and an elastic suspension, wherein the elastic suspension is elastically connected with the first frame and the proof mass.

Preferably, the forming method further includes:

etching on the first substrate to form a first sensing plane electrode and a first driving plane electrode, and etching on the second substrate to form a second sensing plane electrode and a second driving plane electrode;

and packaging the proof mass, the sensing comb, the driving comb and the elastic suspension in a cavity enclosed by the first substrate and the second substrate, and connecting two ends of the first substrate and the second substrate.

Compared with the prior art, the invention has the beneficial effects that:

according to the MEMS device provided by the technical scheme, the sensing combs are arranged on four sides of the proof mass block, and the four groups of driving combs are correspondingly arranged on one sides, far away from the proof mass block, of the four sensing combs one by one, so that a single device of the MEMS device can sense rotation and acceleration, the equivalent function which can be achieved by at least two MEMS sensors in the related technology is realized, and the production cost is reduced.

Drawings

Fig. 1 is a schematic structural diagram of a MEMS device after removing a first substrate and a second substrate in an embodiment of the present invention.

Fig. 2 is a partially enlarged view of a portion a in fig. 1.

FIG. 3 is a schematic structural diagram of a proof mass in an embodiment of the invention.

Fig. 4 is a first schematic diagram of a MEMS device reflecting the directions of the driving signal and the sensing signal under the action of coriolis force according to an embodiment of the present invention.

Fig. 5 is a second schematic diagram of a MEMS device reflecting the directions of the driving signal and the sensing signal under the action of coriolis force according to an embodiment of the present invention.

Fig. 6 is a third schematic diagram of a MEMS device reflecting the directions of the driving signal and the sensing signal under the action of coriolis force according to an embodiment of the present invention.

Fig. 7 is a fourth schematic diagram of a MEMS device reflecting the direction of the drive signal and the sense signal under the action of coriolis force according to an embodiment of the present invention.

Fig. 8 is a first schematic diagram of a MEMS device reflecting the direction of a sensing signal under the action of an inertial force in an embodiment of the present invention.

Fig. 9 is a second schematic diagram of the MEMS device reflecting the direction of the sensing signal under the action of the inertial force in the embodiment of the present invention.

Fig. 10 is a third schematic diagram of a MEMS device reflecting the direction of the sensing signal under the action of the inertial force in the embodiment of the present invention.

FIG. 11 is a graph illustrating the characteristics of a drive signal, an acceleration sense signal, and a rotation (angular velocity) sense signal along an axis when a MEMS device is in operation in accordance with an embodiment of the present invention.

Fig. 12 is a schematic structural diagram of a first substrate in an embodiment of the invention.

Fig. 13 is a schematic structural diagram of a first substrate having a first sensing planar electrode and a first driving planar electrode in an embodiment of the present invention.

Fig. 14 is a schematic structural diagram of a substrate in an embodiment of the invention.

Fig. 15 is a schematic structural diagram of the first substrate and the base plate after being connected through the anode in the embodiment of the present invention.

Fig. 16 is a cross-sectional view of a MEMS device having a first substrate taken along the a-a position in fig. 1 in an embodiment of the invention.

Fig. 17 is a cross-sectional view of a MEMS device having a first substrate taken along the B-B location in fig. 1 in an embodiment of the invention.

Fig. 18 is a cross-sectional view of a MEMS device having a first substrate and a second substrate taken along the B-B location in fig. 1 in an embodiment of the invention.

In the figure: 1. a proof mass; 11. a through hole; 2. a sensing comb; 21. movable sensing comb teeth; 22. a first frame; 23. fixing the sensing comb teeth; 24. a second frame; 3. a drive comb; 31. the movable driving comb teeth; 32. a third frame; 33. fixing the driving comb teeth; 34. a fourth frame; 35. a functional comb; 36. a compensation comb; 4. a first substrate; 41. a first sensing planar electrode; 42. a first driving planar electrode; 5. an anchor point; 6. a second substrate; 61. a second sensing planar electrode; 62. a second drive planar electrode; 7. a substrate; 8. and a resilient suspension.

Detailed Description

The present invention will now be described in more detail with reference to the accompanying drawings, in which the description of the invention is given by way of illustration and not of limitation. The various embodiments may be combined with each other to form other embodiments not shown in the following description.

Referring to fig. 1, 16 and 17, an embodiment of the present invention provides a MEMS device, including: proof mass 1, sensing comb 2, drive comb 3, first substrate 4, anchor point 5, and elastic suspension 8; with reference to fig. 1, by disposing the sensing combs 2 on four sides of the proof mass 1 and disposing four sets of driving combs 3 on one side of the four sensing combs 2 away from the proof mass 1, a single device of the MEMS sensor can sense rotation and acceleration, so as to achieve equivalent functions that can be achieved by at least two MEMS sensors in the related art, thereby reducing the production cost.

Referring to fig. 1, in the present embodiment, the sensing combs 2 are arranged in four groups, respectively, disposed on four sides of the proof mass 1, referring to fig. 2, each group of sensing combs 2 includes a movable sensing comb 21, a first frame 22, a fixed sensing comb 23, and a second frame 24, the movable sensing comb 21 is provided in plural, the first frame 22 integrates the plural movable sensing comb 21, the fixed sensing comb 23 is provided in plurality, the second frame 24 integrates the plurality of fixed sensing combs 23, the movable sensing comb teeth 21 and the fixed sensing comb teeth 23 are interdigitated to form an interdigitated structure, and extends in a direction parallel or substantially parallel to the side length of said proof mass 1 corresponding to its side, wherein the fixed sensing comb 23 is fixed on the first substrate 4, the plurality of elastic suspensions 8 are provided, and a part of the elastic suspensions 8 elastically connect the first frame 22 and the proof mass 1.

Referring to fig. 1, in the present embodiment, the driving combs 3 are arranged in four groups, one for one, and are correspondingly arranged on one side of the four sensing combs 2 away from the proof mass 1, referring to fig. 2, each group of the driving combs 3 includes a movable driving comb 31, a third frame 32, a fixed driving comb 33, and a fourth frame 34, the movable drive comb 31 is provided in plural, the third frame 32 integrates the plurality of movable drive combs 31, the fixed drive comb 33 is provided in plural, the fourth frame 34 integrates the fixed drive comb 33 in plural, the movable drive comb 31 and the fixed drive comb 33 are interdigitated, and extends in a direction perpendicular or substantially perpendicular to the side length of said proof mass 1 corresponding to the side on which it is located, wherein the fixed drive combs 33 are fixed to the first substrate 4 and the third frame 32 is connected to the first frame 22.

Referring to fig. 17, in the present embodiment, the MEMS device further includes a first sensing plane electrode 41 and a first driving plane electrode 42, and the first sensing plane electrode 41 and the first driving plane electrode 42 are both fixedly disposed on the first substrate 4 and both located below the proof mass 1; the first sensing plane electrode 41 measures the movement of the proof mass 1 along the Z-axis; the first drive planar electrode 42 electrostatically dampens the proof mass 1, avoiding contact between the proof mass 1 and the first sensing planar electrode 41.

Referring to fig. 16, in the present embodiment, a plurality of anchor points 5 are provided, specifically, 20 anchor points are provided, the anchor points 5 are all fixed on the first substrate 4, and a portion of the elastic suspension 8 elastically connects the first frame 22 and one or more anchor points 5, and the third frame 32 and one or more anchor points 5; the anchor points 5 connect the proof mass 1, movable sensing combs 21 and movable drive combs 31 to the first substrate 4 and limit the range of motion of the proof mass 1, movable sensing combs 21 and movable drive combs 31 under shock loading, avoiding damage to the MEMS device after shock.

With continued reference to fig. 1 and 2, in order to adjust the bandwidth and reduce the quadrature error, a part of the movable drive comb teeth 31 and a part of the fixed drive comb teeth 33 form a functional comb 35, the rest of the movable drive comb teeth 31 and the rest of the fixed drive comb teeth 33 form a compensation comb 36, the compensation comb 36 is one or more and is uniformly distributed at the side of the functional comb 35, if the power of the functional comb 35 is insufficient to provide the required power, one of the compensation combs 36 is activated, if the power of one compensation comb 36 is still insufficient to provide the required power after being activated, the two compensation combs 36 are activated, and so on until the required power can be achieved.

Referring to fig. 18, as a preferred embodiment, the MEMS device further includes a second substrate 6, the second substrate 6 is disposed on a side of the proof mass 1 away from the first substrate 4, two ends of the first substrate 4 are connected to the second substrate 6 to form a cavity for placing the proof mass 1, the sensing comb 2, the driving comb 3, the anchor point 5 shown in fig. 16, the first sensing plane electrode 41 and the first driving plane electrode 42 shown in fig. 17 shown in fig. 1; by arranging the second substrate 6, an airtight environment can be formed in the MEMS device, and the MEMS device does not need to be placed in vacuum for packaging when being packaged.

With reference to fig. 18, as a preferred embodiment, the MEMS device further includes a second sensing plane electrode 61 and a second driving plane electrode 62, the second sensing plane electrode 61 and the second driving plane electrode 62 are disposed on the second substrate 6, and the first sensing plane electrode 41 and the second sensing plane electrode 61, the first driving plane electrode 42 and the second driving plane electrode 62 are disposed opposite to each other.

In the related art, the precision of the MEMS gyroscope is still low relative to the requirement of a high-performance inertial system, and there are two methods for reducing the error of the MEMS gyroscope: firstly, the design of a sensitive structure is improved or the processing quality is improved; secondly, the error is restrained and compensated by adopting a proper error restraining and control loop compensating method, and the performance of the gyroscope is improved. Machining defects and machining errors affect the geometry and material properties of the MEMS gyroscope and change the resonant frequency of the gyroscope, and manufacturing defects and tolerances are caused by an imbalance in the gyroscope microstructure, producing quadrature errors that are much larger than the motion under the action of coriolis forces.

In the functional integration of the MEMS gyroscope and the accelerometer, it is necessary to effectively isolate the signal components under the action of the inertial force and the coriolis force, and consider the mutual influence between the sensitive axes, so to improve the stability of the performance of the commercial MEMS gyroscope, it is necessary to effectively eliminate the error, and the first sensing plane electrode 41 and the second sensing plane electrode 61 are paired to allow the change of the capacitance to be measured using a differential circuit, which can amplify the output signal of the MEMS device, reduce the error caused by the external vibration, and improve the stability of the performance of the MEMS device.

Referring to fig. 3, further, in order to improve the detection accuracy, a plurality of through holes 11 are formed in the proof mass 1, and when the MEMS device is placed in the cavity containing the inert gas, the through holes 11 can reduce the gas resistance, so that the proof mass 1 can maintain a large movement range, thereby improving the detection accuracy.

Referring to fig. 1, 2, 4-11, embodiments of the present invention also provide non-limiting examples of the operating principles of the MEMS device.

Referring to fig. 1, during operation, a DC actuation potential in series with an AC modulation potential is applied to the proof mass 1 and an AC actuation potential is applied to one or more of the drive combs 3, the combination of the DC actuation potential and the AC actuation potential generating sufficient electrostatic forces to move the proof mass 1 such that the proof mass 1 moves in an oscillatory manner.

Wherein the DC actuating potential may be a constant value, and the voltage thereof is greater than the voltage of other voltage sources of the system, specifically, the DC actuating potential may be higher than 1 volt, or higher than 5 volts, or about 10 volts; wherein the AC actuating potential is applied to one side of the functional comb 35, the AC actuating potential having a low frequency of about 1kHz to about 100kHz and a high frequency of about 100kHz to about 10mHz, and specifically, the AC modulating potential having a low frequency of about 5kHz to about 10kHz and a high frequency of about 500 kHz to about 5 mHz; in some embodiments, the AC modulation potential may have a voltage lower than the DC actuation potential and/or the AC actuation potential.

Applying an alternating driving voltage to a pair of driving combs 3 in a Y-axis direction using a Y-axis as a driving axis, and driving the proof mass 1 to oscillate in the Y-axis direction by the generated electrostatic force, thereby causing a change in a distance between each pair of adjacent movable sensing comb teeth 21 and fixed sensing comb teeth 23 inside a pair of sensing combs 2 in the Y-axis direction, and further changing a capacitance output outward by the pair of sensing combs 2 in the Y-axis direction; at this time, the compensation comb 36 tunes the bandwidth, and a pair of the driving combs 3 and the first and second

driving plane electrodes

42 and 42 in the X-axis direction reduces the quadrature error.

In the case of an oscillation of the proof mass 1 in the Y-axis direction, the sensitivity axis is switched:

referring to FIG. 4, the MEMS device rotates around the Z axis, generating Coriolis force along the X axis, and the Coriolis force moves the proof mass 1, which causes the distance between each pair of adjacent movable sensing comb teeth 21 and fixed sensing comb teeth 23 inside a pair of sensing combs 2 along the X axis to change, thereby changing the capacitance output from the pair of sensing combs 2 along the X axis.

Referring to fig. 9, when the device rotates around the Z-axis, when a linear acceleration is applied along the X-axis, the proof mass 1 is subjected to an inertial force in addition to a coriolis force, and the inertial force moves the proof mass 1, so that a distance between each pair of adjacent movable sensing comb teeth 21 and fixed sensing comb teeth 23 inside a pair of sensing combs 2 along the X-axis direction is changed, thereby changing an output capacitance of the pair of sensing combs 2 along the X-axis direction.

Referring to fig. 7, the MEMS device rotates about the X-axis, generating coriolis forces along the Z-axis, which move the proof mass 1, causing the spacing between the proof mass 1 and the first and second

sensing plane electrodes

41, 61 to change, thereby changing the capacitance between the proof mass 1 and the first and second

sensing plane electrodes

41, 1 and 61.

Referring to fig. 10, when a linear acceleration is applied along the Z-axis under rotation of the device about the X-axis, the proof mass 1 is subjected to an inertial force in addition to the coriolis force, and the inertial force moves the proof mass 1, causing a change in the spacing between the proof mass 1 and the first and second

sensing plane electrodes

41 and 61, thereby changing the capacitance between the proof mass 1 and the first and second

sensing plane electrodes

41 and 61.

Switching a drive shaft, applying an alternating drive voltage to a pair of drive combs 3 in the X-axis direction using the X-axis as the drive shaft, and generating an electrostatic force to drive proof masses 1 to oscillate in the X-axis direction, thereby causing a change in the distance between each pair of adjacent movable and fixed

sensing comb teeth

21 and 23 inside a pair of sensing combs 2 in the X-axis direction, and further changing the capacitance output outward by a pair of sensing combs 2 in the X-axis direction; at this time, the compensation comb 36 tunes the bandwidth, and a pair of the driving combs 3 and the first and second

driving plane electrodes

42 and 42 in the Y-axis direction reduces the quadrature error.

In the case of an oscillation of the proof mass 1 in the X-axis direction, the sensitivity axis is switched:

referring to FIG. 5, the MEMS device rotates around the Z axis, generating Coriolis force along the Y axis, and the Coriolis force moves the proof mass 1, which causes the distance between each pair of adjacent movable sensing comb teeth 21 and fixed sensing comb teeth 23 inside a pair of sensing combs 2 along the Y axis to change, thereby changing the capacitance output from a pair of sensing combs 2 along the Y axis.

Referring to fig. 8, when the device rotates around the Z-axis, when a linear acceleration is applied along the Y-axis, the proof mass 1 is subjected to an inertial force in addition to the coriolis force, and the inertial force moves the proof mass 1, so that the distance between each pair of adjacent movable sensing comb teeth 21 and fixed sensing comb teeth 23 inside a pair of sensing combs 2 along the Y-axis direction is changed, thereby changing the capacitance output from the pair of sensing combs 2 along the Y-axis direction.

Referring to FIG. 6, the MEMS device rotates about the Y axis, generating Coriolis forces along the Z axis, which moves the proof mass 1, causing the spacing between the proof mass 1 and the first and second

sensing plane electrodes

41, 1 and 61.

Referring to fig. 10, when linear acceleration is applied along the Z-axis under rotation of the device about the Y-axis, the proof mass 1 is subjected to an inertial force in addition to the coriolis force, and the inertial force moves the proof mass 1, causing a change in the spacing between the proof mass 1 and the first and second

sensing plane electrodes

41 and 1 and 61.

Based on the principle, on the premise of not changing the hardware structure design of the MEMS device, the sensing of triaxial acceleration and rotation is realized by dynamically switching the sensitivity axis and the driving axis.

It should be noted that, the sensing combs 2, the first sensing plane electrode 41, and the second sensing plane electrode 61 are connected in a differential circuit, if two sensing combs 2 in the Y-axis direction are respectively Y1 and Y2, two sensing combs 2 in the X-axis direction are respectively X1 and X2, the first sensing plane electrode 41 in the Z-axis direction is Z1, and the second sensing plane electrode 61 is Z2, then:

dCx1x2=Cx2–Cx1；

dCy1y2=Cy2–Cy1；

dCz1z2=Cz2–Cz1。

fig. 11 shows the output waveform of the MEMS device over the whole duty cycle with the drive axis and the sensitivity axis switched, as shown in fig. 11, having an oscillating nature as shown at B, E, G, I in fig. 11 if the change in capacitance is caused by rotation, and a stationary nature as shown at A, F, H, J in fig. 11 if the change in capacitance is caused by acceleration, which is a kind of midpoint offset, so each component of the signal can be isolated by filtering; specifically, different waveforms represent that the MEMS device is in different motion states, in fig. 11, a waveform represents that the MEMS device is accelerated in the X-axis direction, B waveform represents that the MEMS device rotates around the Z-axis, C waveform represents that the driving shaft is the X-axis, the proof mass 1 oscillates in the X-axis direction, D waveform represents that the driving shaft is the Y-axis, the proof mass 1 oscillates in the Y-axis direction, E waveform represents that the MEMS device rotates around the Z-axis, F waveform represents that the MEMS device is accelerated in the Y-axis direction, G waveform represents that the MEMS device rotates around the X-axis, H waveform represents that the MEMS device is accelerated in the Z-axis direction, I waveform represents that the MEMS device rotates around the Y-axis, and J waveform represents that the MEMS device is accelerated in the Z-axis direction.

Referring to fig. 12 to 18, the present embodiment further provides a method for forming the MEMS device, where the method includes:

referring to fig. 12, a first substrate 4 is subjected to photolithography and etching application patterning to obtain a first substrate 4 having a concave portion and a convex portion as shown in fig. 12, and a second substrate 6 having a concave portion and a convex portion is obtained in the same manner; wherein the first substrate 4 and the second substrate 6 comprise any suitable substrate material known in the art, for example comprising silicon or any other semiconductor or non-semiconductor material, such as glass, plastic, metal or ceramic, or integrated circuits fabricated thereon.

Referring to fig. 13, photolithography and etching are further performed on the first substrate 4 to form a first sensing plane electrode 41 and a first driving plane electrode 42, and a second sensing plane electrode 61 and a second driving plane electrode 62 are formed on the second substrate 6 in the same manner; wherein the first sensing plane electrode 41, the first driving plane electrode 42, the second sensing plane electrode 61 and the second driving plane electrode 62 are made of a conductive material, such as a semiconductor material including silicon, or a metal material including copper, aluminum, titanium, cobalt, tungsten, titanium nitride or an alloy thereof; the first sensing plane electrode 41, the first driving plane electrode 42, the second sensing plane electrode 61 and the second driving plane electrode 62 have the same or different thicknesses, and may be selected from several to ten micrometers.

Referring to fig. 14, the substrate 7 is polished to a thickness required for forming the MEMS device structure; wherein the base plate 7 comprises any suitable substrate material known in the art, for example comprising silicon or any other semiconductor material, or an integrated circuit fabricated thereon; in addition, with regard to the selection of thicknesses, the thicknesses of proof mass 1, sense combs 2, drive combs 3, first substrate 4, anchor points 5, second substrate 6, base plates 7, and resilient suspensions 8 may be the same or different, on the order of a few to 100 microns, for example, on the order of 5 to 50 microns, for example, 10 to 30 microns.

Referring to fig. 15, the first substrate 4 and the substrate 7 are connected by an anode connection method; the vacuum chamber of the MEMS device is formed by a simple and effective anodic bonding method, the yield can be improved, the production rate can be improved, and the method is suitable for large-scale production.

Referring to fig. 1, 2, 16, and 17, proof mass 1, sense combs 2, drive combs 3, anchors 5, and flexible suspensions 8 are etched on substrate 7 using bosch process (i.e., reactive ion etching), wherein proof mass 1, sense combs 2, drive combs 3, anchors 5, and flexible suspensions 8 comprise any suitable substrate material known in the art, including, for example, silicon or any other semiconductor material.

Wherein the gap between each pair of adjacent movable and fixed

sensing comb teeth

21, 23 and the gap between each pair of adjacent movable and fixed driving

comb teeth

31, 33 is independently selectable from about a few microns to about ten microns, but is not limited to about 1 micron to about 5 microns.

Wherein, the elastic suspension 8 is provided with a plurality of elastic suspensions 8, part of the elastic suspensions 8 elastically connect the first frame 22 with the proof mass 1, part of the elastic suspensions 8 elastically connect the first frame 22 with the anchor points 5, and part of the elastic suspensions 8 elastically connect the third frame 32 with the anchor points 5, further, the thickness of the elastic suspension 8 elastically connecting the first frame 22 with the proof mass 1 is smaller than that of the elastic suspension 8 of the rest part, thereby ensuring that the proof mass 1 can move along the Z axis, and realizing the large-range rotation and acceleration sensing; alternatively, the number of elastic suspensions 8 between the proof mass 1 and the first frame 22, the first frame 22 and the anchor point 5, and the third frame 32 and the anchor point 5 may be increased or decreased; there are several spring beams on each spring suspension 8, and the number of spring beams in each spring suspension 8 or in parts of the spring suspension 8 can be increased or decreased.

Referring to fig. 18, the proof mass 1, the sensing comb 2, the driving comb 3, the anchor points 5 and the elastic suspensions 8 are packaged in a cavity surrounded by the first substrate 4 and the second substrate 6, and two ends of the first substrate 4 and the second substrate 6 are connected; specifically, the first substrate 4 and the second substrate 6 are connected by an anodic bonding method, thereby forming a vacuum chamber of the MEMS device, which contains a vacuum or other inert gas such as nitrogen gas or the like.

The method is simple and effective, adopts the standard equipment process of semiconductor manufacturing, improves the yield of the MEMS device, reduces the manufacturing cost of the MEMS device, is suitable for batch production, can effectively inhibit errors and improves the manufacturing quality of the MEMS device.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, and any insubstantial changes and substitutions made by those skilled in the art based on the present invention are within the protection scope of the present invention.

Claims

1. A MEMS device, comprising:

a proof mass (1);

sensing combs (2) are arranged in four groups and are respectively arranged on four sides of the proof mass (1), each group of sensing combs (2) comprises a plurality of movable sensing comb teeth (21), a first frame (22) integrating the plurality of movable sensing comb teeth (21), a plurality of fixed sensing comb teeth (23) and a second frame (24) integrating the plurality of fixed sensing comb teeth (23), the movable sensing comb teeth (21) and the fixed sensing comb teeth (23) are mutually crossed to form an interdigital structure and extend along the direction parallel to the side length of the proof mass (1) corresponding to the side where the movable sensing comb teeth and the fixed sensing comb teeth (23) are arranged, wherein the fixed sensing comb teeth (23) are fixed on the first substrate (4), and the first frame (22) is elastically connected with the proof mass (1);

the drive combs (3) are arranged in four groups, the drive combs (2) are arranged on one side, far away from the proof mass (1), of the four sense combs (2) in a one-to-one correspondence mode, each drive comb (3) comprises a plurality of movable drive comb teeth (31), a third frame (32) integrating the plurality of movable drive comb teeth (31), a plurality of fixed drive comb teeth (33) and a fourth frame (34) integrating the plurality of fixed drive comb teeth (33), the movable drive comb teeth (31) and the fixed drive comb teeth (33) are mutually crossed to form an interdigital structure and extend along the direction, perpendicular to the side length of the proof mass (1), corresponding to the side where the movable drive comb teeth and the fixed drive comb teeth (33) are arranged, wherein the fixed drive comb teeth (33) are fixed on the first substrate (4), and the third frame (32) is connected with the first frame (22).

2. The MEMS device according to claim 1, further comprising the first substrate (4), and a first sensing plane electrode (41) fixedly arranged on the first substrate (4), the first sensing plane electrode (41) being arranged below the proof mass (1).

3. The MEMS device according to claim 2, further comprising a first drive planar electrode (42) fixedly arranged on the first substrate (4), the first drive planar electrode (42) being arranged below the proof mass (1).

4. A MEMS device according to claim 3, further comprising a plurality of anchor points (5), a plurality of said anchor points (5) each being fixed to said first substrate (4), said first frame (22) and said third frame (32) each being elastically connected to one or more of said anchor points (5).

5. The MEMS device, as set forth in claim 1, wherein a portion of the movable drive comb teeth (31) and a portion of the fixed drive comb teeth (33) constitute a functional comb (35), and the remaining movable drive comb teeth (31) and the remaining fixed drive comb teeth (33) constitute one or more compensation combs (36) disposed laterally of the functional comb (35).

6. The MEMS device according to claim 4, further comprising a second substrate (6) arranged on a side of the proof mass (1) remote from the first substrate (4), the first substrate (4) and the second substrate (6) being connected at both ends forming a cavity in which the proof mass (1), the sensing combs (2), the driving combs (3), the anchor points (5), the first sensing plane electrodes (41) and the first driving plane electrodes (42) are placed.

7. The MEMS device, as set forth in claim 6, further comprising a second sensing planar electrode (61) and a second driving planar electrode (62) disposed on the second substrate (6), the first sensing planar electrode (41) and the second sensing planar electrode (61), the first driving planar electrode (42) and the second driving planar electrode (62) being disposed opposite to each other two by two.

8. MEMS device according to claim 6, characterized in that a plurality of through holes (11) is provided through the proof mass (1).

9. A method of forming the MEMS device of claim 1, wherein the method of forming comprises:

grinding the substrate (7) to a thickness required for forming the MEMS device structure;

and etching and forming a proof mass (1), a sensing comb (2), a driving comb (3) and an elastic suspension (8) on the substrate (7), wherein the elastic suspension (8) elastically connects the first frame (22) and the proof mass (1).

10. The method of forming as claimed in claim 9, further comprising:

etching on the first substrate (4) to form a first sensing plane electrode (41) and a first driving plane electrode (42), and etching on the second substrate (6) to form a second sensing plane electrode (61) and a second driving plane electrode (62);

and encapsulating the proof mass (1), the sensing comb (2), the driving comb (3) and the elastic suspension (8) in a cavity enclosed by the first substrate (4) and the second substrate (6), and connecting two ends of the first substrate (4) and the second substrate (6).