Micro-electro-mechanical system gyroscope

Abstract

The application discloses a micro-electro-mechanical system gyroscope and belongs to the technical field of sensors. The gyroscope comprises a first wafer layer, a second wafer layer and a third wafer layer which are bonded in sequence. The first wafer layer is provided with a plurality of functional electrodes which are perpendicular to the first wafer layer. Adjacent functional electrodes are provided with isolation through holes which are perpendicular to the first wafer layer. The plurality of functional electrodes are insulated from each other through the isolation through holes. The plurality of functional electrodes comprise a first frequency modulation electrode. The second wafer layer comprises at least one mass. Each mass is suspended on the first wafer layer through an anchor point structure. The mass can vibrate along a direction which is parallel or perpendicular to the second wafer layer around the anchor point structure. The third wafer layer is provided with a second frequency modulation electrode on a bonding surface of the third wafer layer which is bonded to the second wafer layer. The first frequency modulation electrode and the second frequency modulation electrode are used for adjusting the detection frequency of the gyroscope. Therefore, the difference between the driving frequency and the detection frequency of the gyroscope can be adjusted, and the sensitivity and stability of the gyroscope are ensured.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and more particularly to a microelectromechanical system gyroscope. Background Technology

[0002] A gyroscope is an inertial device used to measure the angular velocity of an object along the X, Y, and Z axes. Currently, MEMS (micro electromechanical systems) gyroscopes are widely used. MEMS gyroscopes are inertial devices manufactured using microelectromechanical processes, featuring small size, high reliability, low cost, and suitability for mass production.

[0003] Currently, a related patent with patent number CN 102607543 B discloses a MEMS gyroscope comprising three silicon wafer layers directly bonded to silicon. The three silicon wafer layers are, sequentially, a fixed electrode wafer layer, a mass block wafer layer, and a capping wafer layer. The fixed electrode wafer layer is a through-hole silicon wafer layer with multiple through-hole silicon electrodes perpendicular to it. By using through-hole silicon as the electrode material for a variable capacitance sensor, it forms the two poles of a variable capacitor with the mass block electrodes in the mass block wafer layer. By detecting changes in capacitance, the angular velocity generated by the gyroscope under the Coriolis force can be calculated.

[0004] Since the sensitivity and stability parameters of MEMS gyroscopes are related to the values ​​of the driving frequency Fd and the detection frequency Fs, especially the difference between them ΔF = Fd - Fs, this difference often needs to be adjusted. However, the aforementioned gyroscopes cannot perform frequency adjustment. Therefore, how to achieve frequency adjustment of the gyroscope to ensure its sensitivity and stability is a pressing problem that needs to be solved. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a microelectromechanical system gyroscope that overcomes or at least partially solves the above problems, the gyroscope having a frequency adjustment function, which can ensure the sensitivity and stability of the gyroscope components.

[0006] This invention provides a microelectromechanical system gyroscope, the gyroscope comprising a first wafer layer, a second wafer layer, and a third wafer layer bonded sequentially;

[0007] The first wafer layer has a plurality of functional electrodes perpendicular to the first wafer layer, and there are isolation vias perpendicular to the first wafer layer between adjacent functional electrodes. The plurality of functional electrodes are mutually insulated and isolated through the isolation vias. The plurality of functional electrodes include a first frequency modulation electrode.

[0008] The second wafer layer includes at least one mass block, each of which is suspended from the first wafer layer by an anchor structure, and the mass block can vibrate about the anchor structure in a direction parallel or perpendicular to the second wafer layer.

[0009] The third wafer layer has a second frequency modulation electrode on the side bonded to the second wafer layer. The first frequency modulation electrode and the second frequency modulation electrode are used to adjust the detection frequency of the gyroscope.

[0010] Optionally, an insulating layer is provided on the side of the first wafer layer away from the second wafer layer, and a plurality of first conductive holes corresponding one-to-one with the plurality of functional electrodes are formed on the insulating layer, and electrode pads for electrical connection with the corresponding functional electrodes are provided in the plurality of first conductive holes.

[0011] Optionally, the first wafer layer includes an inner wafer layer and an outer wafer layer located outside the inner wafer layer. An isolation trench perpendicular to the first wafer layer is provided between the inner wafer layer and the outer wafer layer. The inner wafer layer and the outer wafer layer are mutually insulated and isolated by the isolation trench. The plurality of functional electrodes are located on the inner wafer layer, and the outer wafer layer is electrically connected to the second frequency modulation electrode.

[0012] The insulating layer has a second conductive hole corresponding to the outer wafer layer, and the second conductive hole has an electrode pad for electrical connection with the outer wafer layer.

[0013] Optionally, the insulating layer is a silicon oxide or silicon nitride layer.

[0014] Optionally, a conductive layer electrically connected to the second frequency modulation electrode is provided on the side of the third wafer layer away from the second wafer layer.

[0015] Optionally, the plurality of functional electrodes may further include a mass block electrode, a driving electrode, a driving detection electrode, a feedback electrode, and a detection electrode.

[0016] Optionally, the second wafer layer includes four mass blocks symmetrically arranged along the center of the gyroscope, the third wafer layer has a second frequency tuning electrode arranged corresponding to each mass block, and the first wafer layer has a mass block electrode, a driving electrode, a driving detection electrode, a feedback electrode, a detection electrode, and a first frequency tuning electrode arranged corresponding to each mass block.

[0017] Optionally, the second wafer layer has a first groove on the side bonded to the first wafer layer, and the third wafer layer has a second groove on the side bonded to the second wafer layer. The mass block vibrates in the first groove and the second groove in a direction parallel or perpendicular to the second wafer layer.

[0018] Optionally, the second wafer layer and the third wafer layer are bonded together by a bonding layer, which is a conductive layer.

[0019] Optionally, the first wafer layer, the second wafer layer, and the third wafer layer are all silicon wafers.

[0020] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0021] This invention provides a microelectromechanical system gyroscope, which forms a first frequency-modulating electrode on a first wafer layer and a second frequency-modulating electrode on a third wafer layer, such that the first and second frequency-modulating electrodes are located on opposite sides of a mass block on the second wafer layer. When the mass block vibrates along a direction parallel or perpendicular to the second wafer layer under the action of the Coriolis force, the detection frequency of the gyroscope can be adjusted by the first and second frequency-modulating electrodes, thereby adjusting the difference between the driving frequency and the detection frequency of the gyroscope and ensuring the sensitivity and stability of the gyroscope device.

[0022] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0023] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0024] In the attached diagram:

[0025] Figure 1 This is a cross-sectional view of a microelectromechanical system gyroscope provided in an embodiment of the present invention;

[0026] Figure 2 This is a partial schematic diagram of a microelectromechanical system gyroscope provided in an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of a microelectromechanical system gyroscope provided in an embodiment of the present invention, as shown below. Figure 1As shown, the microelectromechanical system gyroscope includes a first wafer layer 10, a second wafer layer 20, and a third wafer layer 30 bonded together in sequence.

[0029] The first wafer layer 10 has a plurality of functional electrodes perpendicular to the first wafer layer 10. There are isolation vias 10a perpendicular to the first wafer layer between adjacent functional electrodes. The plurality of functional electrodes are mutually insulated and isolated through the isolation vias 10a. The plurality of functional electrodes include a first frequency modulation electrode 11.

[0030] The second wafer layer 20 includes at least one mass block 21, each mass block 21 being suspended from the first wafer layer 10 by an anchor structure 22, and the mass block 21 being able to vibrate about the anchor structure 22 in a direction parallel or perpendicular to the second wafer layer 20.

[0031] The third wafer layer 30 has a second frequency modulation electrode 31 on the side bonded to the second wafer layer 20. The first frequency modulation electrode 11 and the second frequency modulation electrode 31 are used to adjust the detection frequency of the gyroscope.

[0032] In this embodiment of the invention, a first frequency-modulating electrode is formed on a first wafer layer, and a second frequency-modulating electrode is formed on a third wafer layer, such that the first and second frequency-modulating electrodes are located on opposite sides of a mass block on the second wafer layer, respectively. When the mass block vibrates in a direction parallel or perpendicular to the second wafer layer under the action of the Coriolis force, the detection frequency of the gyroscope can be adjusted by the first and second frequency-modulating electrodes, thereby adjusting the difference between the driving frequency and the detection frequency of the gyroscope and ensuring the sensitivity and stability of the gyroscope device.

[0033] In this embodiment, the first wafer layer 10, the second wafer layer 20, and the third wafer layer 30 are all silicon wafer layers. Specifically, they can be highly doped single-crystal silicon layers. The first frequency modulation electrode 11 and the second frequency modulation electrode 31 are also silicon electrode materials. The isolation via 10a can be a through silicon via (TSV).

[0034] Optionally, an insulating layer 40 is provided on the side of the first wafer layer 10 away from the second wafer layer 20. The insulating layer 40 has multiple first conductive holes 40a corresponding to multiple functional electrodes. Each of the multiple first conductive holes 40a contains an electrode pad 41 for electrical connection to its corresponding functional electrode. The multiple functional electrodes can be electrically connected to an external circuit through their corresponding electrode pads 41 to achieve different functions.

[0035] In this embodiment, the electrode pad 41 can be a metal electrode pad such as gold, silver, platinum, or aluminum, or other conductive alloy materials, etc. The present invention does not limit this.

[0036] Optionally, the first wafer layer 10 includes an inner wafer layer S1 and an outer wafer layer S2 located outside the inner wafer layer S1. An isolation trench 10b perpendicular to the first wafer layer 10 is provided between the inner wafer layer S1 and the outer wafer layer S2, and the inner wafer layer S1 and the outer wafer layer S2 are mutually insulated from each other through the isolation trench 10b. Multiple functional electrodes are located on the inner wafer layer S1, and the outer wafer layer S2 is electrically connected to the second frequency modulation electrode 31.

[0037] The insulating layer 40 is provided with a second conductive hole 40b corresponding to the outer wafer layer S2, and an electrode pad 41 for electrical connection with the outer wafer layer is provided in the second conductive hole 40b.

[0038] In the above implementation, both the first frequency modulation electrode 11 and the second frequency modulation electrode 31 can be electrically connected to external circuits with different voltages through the electrode pad 41, so as to realize the adjustment of the detection frequency in different directions respectively.

[0039] Optionally, the insulating layer 40 is a silicon oxide or silicon nitride layer to isolate moisture and prevent electric shock from contacting the conductor.

[0040] Optionally, a conductive layer 50, electrically connected to the second frequency modulation electrode 31, is provided on the side of the third wafer layer 30 away from the second wafer layer 20. By providing the conductive layer 50, it is easier to make the second frequency modulation electrode 31 electrically connected to the external circuit during subsequent packaging.

[0041] It should be noted that in this embodiment, the second frequency modulation electrode 31 can be electrically connected to the external circuit through the conductive layer 50 or through the electrode pad 41 in the second conductive hole 40b to achieve the frequency modulation function.

[0042] Optionally, the second wafer layer 20 has a first groove 20a on the side bonded to the first wafer layer 10, and the third wafer layer 30 has a second groove 30a on the side bonded to the second wafer layer 20. The mass block 21 vibrates in the first groove 20a and the second groove 30a in a direction parallel or perpendicular to the second wafer layer 20 to ensure that the mass block has sufficient space to move.

[0043] Optionally, the second wafer layer 20 and the third wafer layer 30 are bonded together by a bonding layer 60, which is a conductive layer. Specifically, the bonding layer 60 can be an Au-Si layer or a Si-SiO2 layer.

[0044] In other implementations of this embodiment, the second wafer layer 20 and the first wafer layer 10 can also be bonded together via the bonding layer 50. Alternatively, the first wafer layer 10, the second wafer layer 20, and the third wafer layer 30 can also be bonded together using Si-Si direct bonding. This embodiment does not limit this aspect.

[0045] Optionally, the multiple functional electrodes may also include a mass block electrode 12, a driving electrode, a driving detection electrode, a feedback electrode, and a detection electrode.

[0046] Each of the aforementioned functional electrodes can be connected to an external circuit via its corresponding electrode pad. When the device is operating, a differential driving voltage is applied to the driving electrode by the external circuit to excite the gyroscope's driving mode. The driving detection electrode can differentially detect the motion state of the driving mode and feed the detection result back to the driving electrode through the external circuit, thus achieving closed-loop driving. The detection electrode can differentially detect the motion state of the gyroscope in the detection mode and feed the detection result back to the feedback electrode through the external circuit, forming closed-loop detection.

[0047] Figure 2 This is a partial schematic diagram of a microelectromechanical system gyroscope provided in an embodiment of the present invention, such as... Figure 2 As shown, the second wafer layer 20 includes four mass blocks 21 symmetrically distributed about the center of the gyroscope structure, denoted as first mass block 21a, second mass block 21b, third mass block 21c, and fourth mass block 21d. Specifically, first mass block 21a and third mass block 21c are symmetrically arranged about the negative X-axis; second mass block 21b and fourth mass block 21d are symmetrically arranged about the positive X-axis; first mass block 21a and second mass block 21b are symmetrically arranged about the positive Y-axis; third mass block 21c and fourth mass block 21d are symmetrically arranged about the negative Y-axis; first mass block 21a and fourth mass block 21d are centrally symmetrically arranged; and third mass block 21c and second mass block 21b are centrally symmetrically arranged. The mass blocks are connected by coupling elastic beams.

[0048] A three-dimensional spatial coordinate system containing X-axis, Y-axis and Z-axis is established with the center point of the first wafer layer 10 as the origin. The X-axis and Y-axis are parallel to the end face of the first wafer layer 10, and the Z-axis is perpendicular to the end face of the first wafer layer 10.

[0049] like Figure 2 As shown, the first wafer layer 10 has mass block electrodes (pm), driving electrodes (D-, D+), driving detection electrodes (DS-, DS+), feedback electrodes (Xb-, Xb+, Yb-, Yb+), detection electrodes (Xs-, Xs+, Ys+, Ys-), and a first frequency modulation electrode (not shown in the figure) arranged corresponding to each mass block 21.

[0050] It should be noted that, in this embodiment, the area on the inner wafer layer S1 of the first wafer layer 10, excluding the aforementioned mass block electrode, driving electrode, driving detection electrode, feedback electrode, and detection electrode, can all be configured as the first frequency modulation electrode. The third wafer layer 30 has a second frequency modulation electrode 31 arranged corresponding to each mass block 21.

[0051] In one implementation of this embodiment, for a Y-axis gyroscope rotating about the X-axis, the second frequency-modulated electrode 31 can be disposed on both sides of the anchor point structure of each mass block 21 along the Y-axis direction (e.g., Figure 2 Above the feedback electrodes Yb+, Yb- and the detection electrode Xs+). For an X-axis gyroscope rotating about the Y-axis, the second frequency-modulated electrode 31 can be arranged on both sides of the anchor point structure of each mass block 21 along the X-axis direction (e.g., above the feedback electrodes Yb+, Yb- and the detection electrode Xs+). Figure 2 Above the feedback electrodes Xb+ and Xb- and the detection electrode Xs-.

[0052] It should be noted that the above Figure 2 The arrangement of each electrode shown is merely an example. In other implementations of this embodiment, each electrode may be arranged in other ways, and this embodiment does not limit this.

[0053] The technical solutions described in the embodiments of this application have at least the following technical effects or advantages:

[0054] This invention provides a microelectromechanical system gyroscope, which forms a first frequency-modulating electrode on a first wafer layer and a second frequency-modulating electrode on a third wafer layer, such that the first and second frequency-modulating electrodes are located on opposite sides of a mass block on the second wafer layer. When the mass block vibrates along a direction parallel or perpendicular to the second wafer layer under the action of the Coriolis force, the detection frequency of the gyroscope can be adjusted by the first and second frequency-modulating electrodes, thereby adjusting the difference between the driving frequency and the detection frequency of the gyroscope and ensuring the sensitivity and stability of the gyroscope device.

[0055] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0056] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0057] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

Claims

1. A microelectromechanical system gyroscope, characterized in that, The gyroscope comprises a first wafer layer, a second wafer layer, and a third wafer layer bonded together in sequence; The first wafer layer has a plurality of functional electrodes perpendicular to the first wafer layer, and there are isolation vias perpendicular to the first wafer layer between adjacent functional electrodes. The plurality of functional electrodes are mutually insulated and isolated through the isolation vias. The plurality of functional electrodes include a first frequency modulation electrode. The second wafer layer includes at least one mass block, each of which is suspended from the first wafer layer by an anchor structure, and the mass block can vibrate about the anchor structure in a direction parallel or perpendicular to the second wafer layer. The third wafer layer has a second frequency modulation electrode on the side bonded to the second wafer layer. The first frequency modulation electrode and the second frequency modulation electrode are used to adjust the detection frequency of the gyroscope. An insulating layer is provided on the side of the first wafer layer away from the second wafer layer. A plurality of first conductive holes are formed on the insulating layer, each corresponding to one of the plurality of functional electrodes. An electrode pad for electrical connection with the corresponding functional electrode is provided in the plurality of first conductive holes. The first wafer layer includes an inner wafer layer and an outer wafer layer located outside the inner wafer layer. An isolation trench perpendicular to the first wafer layer is provided between the inner wafer layer and the outer wafer layer. The inner wafer layer and the outer wafer layer are mutually insulated and isolated by the isolation trench. The plurality of functional electrodes are located on the inner wafer layer. The outer wafer layer is electrically connected to the second frequency modulation electrode. The insulating layer has a second conductive hole corresponding to the outer wafer layer, and the second conductive hole has an electrode pad for electrical connection with the outer wafer layer.

2. The microelectromechanical system gyroscope according to claim 1, characterized in that, The insulating layer is a silicon oxide or silicon nitride layer.

3. The microelectromechanical system gyroscope according to claim 1, characterized in that, The third wafer layer has a conductive layer on the side away from the second wafer layer that is electrically connected to the second frequency modulation electrode.

4. The microelectromechanical system gyroscope according to claim 1, characterized in that, The plurality of functional electrodes also include a mass block electrode, a driving electrode, a driving detection electrode, a feedback electrode, and a detection electrode.

5. The microelectromechanical system gyroscope according to claim 4, characterized in that, The second wafer layer includes four mass blocks symmetrically arranged along the center of the gyroscope. The third wafer layer has a second frequency modulation electrode arranged corresponding to each mass block. The first wafer layer has a mass block electrode, a driving electrode, a driving detection electrode, a feedback electrode, a detection electrode, and a first frequency modulation electrode arranged corresponding to each mass block.

6. The microelectromechanical system gyroscope according to claim 1, characterized in that, The second wafer layer has a first groove on the side bonded to the first wafer layer, and the third wafer layer has a second groove on the side bonded to the second wafer layer. The mass block vibrates in the first groove and the second groove in a direction parallel or perpendicular to the second wafer layer.

7. The microelectromechanical system gyroscope according to claim 1, characterized in that, The second wafer layer and the third wafer layer are bonded together by a bonding layer, which is a conductive layer.

8. The microelectromechanical system gyroscope according to claim 1, characterized in that, The first wafer layer, the second wafer layer, and the third wafer layer are all silicon wafers.

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