CN113607975A

CN113607975A - Position detection and calibration device for MEMS sensor

Info

Publication number: CN113607975A
Application number: CN202110805167.5A
Authority: CN
Inventors: 董林玺; 程恋; 刘超然
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Kaiweili Sensing Technology Co ltd
Priority date: 2021-07-16
Filing date: 2021-07-16
Publication date: 2021-11-05
Anticipated expiration: 2041-07-16
Also published as: CN113607975B

Abstract

The invention provides a position detection and calibration device for a MEMS sensor. The device is a center-symmetric structure, comprising a substrate, a center support table, a movable electrode, a fixed electrode, a cantilever beam, an inclined beam and a ring beam, and a center support The platform is located in the center of the base plate, the center of the four sides of the central support platform is connected to the movable electrode through cantilever beams, the four corners of the central support platform are connected with inclined beams, the inclined beams are connected to the annular beam, and the other end of the annular beam passes through the aiming point. It is fixed on the base plate, the movable electrode is opposite to the fixed electrode, and constitutes a comb-tooth-shaped capacitor pair with equal spacing and cross-distribution, and the fixed electrode is fixed on the base plate through the anchor point. The device of the invention is used for detecting whether the MEMS sensor is located in the center of the micro-platform, achieving the purpose of detecting and calibrating the position of the MEMS sensor with high sensitivity, and realizing the high-precision calibration of the position of the MEMS sensor.

Description

Position detection and calibration device for MEMS sensor

Technical Field

The invention relates to the technical field of position calibration of MEMS sensors, in particular to a position detection and calibration device for an MEMS sensor.

Background

With the rapid development of micro-electro-mechanical systems (MEMS), MEMS sensors are widely used in the fields of automotive electronics, aerospace, weaponry, medical devices, and the like. However, after the MEMS sensor is used for a period of time, the sensitivity of the MEMS sensor deviates due to environmental factors such as aging and temperature, and whether the signal measured by the MEMS sensor is accurate and directly relates to the performance of the product, so the sensitivity output by the MEMS sensor needs to be calibrated.

In the prior art, there are two main methods for calibrating MEMS sensors. One is off-line or on-line calibration by an additional standard calibration device. Another is MEMS sensor self-calibration that integrates a microactuator in a MEMS sensor that can provide standard physical actuation of the MEMS sensor, and a detection system that can detect the accuracy of the physical actuation provided by the microactuator.

However, misalignment of the MEMS sensor with the center of the micro-platform during calibration of the sensitivity of the MEMS sensor affects the accuracy of the calibration. Existing micro-platforms for MEMS sensor calibration ignore this error. Therefore, the position detection and calibration device for the MEMS sensor provided by the invention can detect whether the MEMS sensor is positioned at the center of the micro platform or not, and has important significance for improving the calibration precision of the MEMS sensor.

Disclosure of Invention

The invention aims to provide a position detection and calibration device for a MEMS sensor, so as to improve the calibration accuracy of the MEMS sensor.

The invention adopts the following technical scheme:

the device is of a centrosymmetric structure and comprises a substrate, a central supporting platform, a movable electrode, a fixed electrode, a cantilever beam, an inclined beam and a ring beam, wherein the central supporting platform is positioned in the center of the substrate, the centers of four sides of the central supporting platform are connected with the movable electrode through the cantilever beam, four corners of the central supporting platform are connected with the inclined beam, the inclined beam is connected with the ring beam, the other end of the ring beam is fixed on the substrate through an aiming point, the movable electrode is opposite to the fixed electrode to form a comb-shaped capacitor pair which is distributed in an equidistant and crossed manner, and the fixed electrode is fixed on the substrate through an anchor point.

Furthermore, the annular beam is composed of two straight beams and two arc-shaped beams at the end parts.

Furthermore, the thicknesses of the movable electrode and the fixed electrode are the same, the comb-shaped capacitance plates of the movable electrode and the comb-shaped capacitance plates of the fixed electrode are distributed at equal intervals and are equal to each other, the size of each comb-shaped capacitance plate is the same, the comb-shaped capacitance plates of the movable electrode and the comb-shaped capacitance plates of the fixed electrode are distributed in a crossed mode at equal intervals, and the distance from the comb-shaped capacitance plates of the movable electrode to the fixed electrode is equal to the distance from the comb-shaped capacitance plates of the fixed electrode to the movable electrode.

Furthermore, the substrate is made of borosilicate glass, and the central support platform, the movable electrode, the fixed electrode, the cantilever beam, the inclined beam and the annular beam are all made of monocrystalline silicon wafers.

Further, the device is manufactured by the following steps:

(a) preparing a double-side polished 4-inch-sized monocrystalline silicon wafer;

(b) transferring the figures of the suspended space area, the central support platform, the movable electrode, the fixed electrode, the cantilever beam, the inclined beam and the annular beam of the device to the back of the silicon wafer by adopting a photoetching process; thinning the area to 200-300um by using a dry etching process, removing the photoresist and cleaning the silicon wafer; the suspension area is an area except for the substrate, the central support platform, the movable electrode, the fixed electrode, the cantilever beam, the inclined beam, the annular beam and the anchor point;

(c) removing the oxide film on the back of the silicon wafer by adopting a wet etching process;

(d) preparing a smooth borosilicate glass substrate;

(e) manufacturing anchor points on the front surface of the borosilicate glass substrate by adopting a bonding process;

(f) bonding the back surface of the silicon wafer and the front surface of the borosilicate glass substrate together through an anchor point, and cleaning the silicon wafer;

(g) transferring the patterns of the central support platform, the movable electrode, the fixed electrode, the cantilever beam, the inclined beam and the annular beam of the device to the front surface of the silicon wafer by adopting a photoetching process; sputtering a layer of metal aluminum electrode in the area by adopting a metal sputtering process, and cleaning a silicon wafer;

(h) transferring the suspended area graph of the device to the front surface of the silicon wafer by adopting a photoetching process; etching through the suspended space area by adopting a dry etching process, removing the photoresist and cleaning the silicon wafer;

(i) after dicing, the preparation is completed.

Further, the device is used for detecting and calibrating the position of the MEMS sensor, the device is fixed at the central position of the micro platform, the MEMS sensor is placed at the center of a central supporting platform of the device, a certain amount of volume load force downwards in the Z direction is not applied to the central supporting platform by the MEMS sensor, when the MEMS sensor is positioned at the central position of the central supporting platform, the movable electrode generates equal downward displacement in the Z-axis direction, the opposite effective areas of the movable electrode and the opposite fixed electrodes respectively generate the same reduction value, and the corresponding four capacitance values are caused to change the same; when the MEMS sensor deviates from the central position of the central support platform, the movable electrode generates downward displacement in different z-axis directions, and the effective areas of the movable electrode, which are just opposite to the corresponding fixed electrodes, generate different reduction values, so that the four corresponding capacitance values are different in change; the device is connected with an external processing circuit, converts the capacitance value into a voltage value, and judges the position of the MEMS sensor by comparing the four voltage values;

when the MEMS sensor deviates from the central position of the central support platform, the position of the MEMS sensor is moved until the four voltage values are equal according to the magnitude and the variation condition of the four voltage values, and then the MEMS sensor is moved to the central position of the central support platform.

Furthermore, when the center of the central supporting plate of the MEMS sensor is positioned in the device and is deviated to the positive direction of the x axis, the mass of the positive direction of the x axis is larger than the mass of the negative direction of the x axis, under the action of the same volume loading force, the downward acceleration of the Z direction of the positive direction of the x axis is smaller than the downward acceleration of the Z direction of the negative direction of the x axis, so that the downward displacement of the Z direction of the movable electrode in the positive direction of the x axis is smaller than the downward displacement of the Z direction of the movable electrode in the negative direction of the x axis, the positive effective area of the movable electrode in the positive direction of the x axis and the fixed electrode opposite to the movable electrode is larger than the positive effective area of the fixed electrode opposite to the movable electrode in the negative direction of the x axis, the capacitance value of the positive direction of the x axis is larger than the capacitance value of the negative direction of the x axis due to the positive proportion of the capacitance value to the positive effective area of the positive direction of the x axis, and the voltage value of the positive direction of the x axis is larger than the voltage value of the negative direction of the x axis, when the absolute value of the difference value between the voltage value in the positive direction of the x axis and the voltage value in the negative direction of the x axis is increased, the MEMS sensor is far away from the central position of the central support platform; when the absolute value of the difference value between the voltage value in the positive direction of the x axis and the voltage value in the negative direction of the x axis becomes smaller, the MEMS sensor is close to the central position of the central support platform;

because the whole structure of the device is centrosymmetric, the same analysis is carried out in the y-axis direction: when the center of a central supporting plate of the MEMS sensor is positioned in the device and is deviated to the positive direction of a y axis, the mass of the positive direction of the y axis is larger than the mass of the negative direction of the y axis, under the action of the same volume loading force, the downward acceleration of the Z direction of the positive direction of the y axis is smaller than the downward acceleration of the Z direction of the negative direction of the y axis, so that the downward displacement of the Z direction of a movable electrode in the positive direction of the y axis is smaller than the downward displacement of the Z direction of a movable electrode in the negative direction of the y axis, the positive effective area of the movable electrode in the positive direction of the y axis and a fixed electrode opposite to the movable electrode is larger than the positive effective area of the fixed electrode opposite to the movable electrode in the negative direction of the y axis, the capacitance value in the positive direction of the y axis is larger than the capacitance value in the negative direction of the y axis due to the positive proportion of the capacitance value to the positive effective area, and the voltage value in the positive direction of the y axis is larger than the voltage value in the negative direction of the y axis, when the absolute value of the difference value between the voltage value in the positive direction of the y axis and the voltage value in the negative direction of the y axis is increased, the MEMS sensor is far away from the central position of the central support platform; when the absolute value of the difference between the positive voltage value of the y-axis and the negative voltage value of the y-axis becomes smaller, the MEMS sensor approaches the center position of the center support table.

The invention has the beneficial effects that:

1. the position detection and calibration device for the MEMS sensor is based on the principle of a capacitive micro mechanical accelerometer, is used for detecting whether the MEMS sensor is positioned at the center of a micro platform or not, achieves the purpose of detecting and calibrating the position of the MEMS sensor with high sensitivity, and realizes the high-precision calibration of the position of the MEMS sensor. The device is externally connected with a processing circuit and converts the capacitance value into a readable voltage value. The MEMS sensor is arranged on the central support platform of the device, when the MEMS sensor is positioned at the central position of the central support platform, four capacitors formed by four movable electrodes and four fixed electrodes of the device have equal capacitance values, and the output voltages of the four capacitors are equal; when the MEMS sensor deviates from the central position of the central support platform, four capacitors formed by four movable electrodes and four fixed electrodes of the device have unequal capacitance values, and the output voltages of the four capacitors are unequal; thereby detecting the offset direction and distance of the placement position of the MEMS sensor. According to the change situation of the four voltage values, the position of the MEMS sensor is moved until the four output voltages are equal, and then the MEMS sensor is moved to the central position of the central support platform of the device, so that the calibration of the placement position of the MEMS sensor is realized.

2. The invention is used in the position detection and calibration device of the MEMS sensor, a central support platform is positioned in the center of the device, four corners of the central support platform are respectively connected with four inclined beams, the four inclined beams are respectively connected with four annular beams, the other ends of the four annular beams are respectively fixed on a substrate through four aiming points, when a certain volume load force downwards in the Z direction is applied to the central support platform, the central support platform generates downward displacement in the Z direction, and the four inclined beams and the four annular beams support the central support platform, so that the device has better sensitivity and elasticity. The adopted annular beam has better elasticity due to the annular structure, and the elastic coefficient can be reduced by increasing the length of the annular beam and reducing the width and the thickness of the annular beam, so that better elasticity is realized. The inclined beam is used for connecting the central support platform and the annular beam, and the annular beam has better elasticity and can generate larger deformation under the action of force, so that the central support platform generates larger displacement. The structure that the center supporting platform is fixed on the aiming point by adopting the inclined beam and the annular beam has better elasticity than the structure that the center supporting platform is directly fixed on the aiming point by adopting the inclined beam only, thereby realizing larger displacement. The cantilever beam is used for connecting the central support platform and the movable electrode, so that the elasticity of the whole structure is increased, and when the central support platform is subjected to a certain volume load force downwards in the Z direction, the movable electrode generates larger vibration so as to generate larger downward displacement in the Z direction. The central support platform is provided with a certain amount of volume load force in the downward Z direction, the annular beam and the inclined beam structure with good elasticity realize that the central support platform generates downward displacement in the Z direction, the movable electrode connected with the cantilever beam generates downward displacement in the Z direction, so that the change of the capacitance value of the capacitance formed by the movable electrode and the fixed electrode is caused, the change condition of the capacitance value can reflect whether the position of the MEMS sensor is located at the central position of the micro platform, the MEMS sensor can be moved until the four capacitance values are equal through the change condition of the capacitance value, and at the moment, the MEMS sensor is located in the center of the central support platform, so that the position calibration of the MEMS sensor is realized, and the position deviation problem of the MEMS sensor is solved.

3. The invention is used in the position detection and calibration device of the MEMS sensor, the distance between each capacitor plate of the movable electrode and each capacitor plate of the adjacent fixed electrode is equal, the distance between the movable electrode plate and the fixed electrode plate is fully utilized, so that each plate and the adjacent plate can form a capacitor pair with equal capacitance, when a certain volume load force downwards along the Z direction is applied to the central support platform, the movable electrode generates downward displacement along the Z direction, and the effective area of the movable electrode opposite to the fixed electrode d is changed, thereby changing the capacitance. The comb-shaped capacitor plates of the fixed electrode and the comb-shaped capacitor plates of the movable electrode are distributed in an equidistant crossing way, and the capacitance value of the capacitor pair formed by the comb-shaped capacitor plates distributed in the non-equidistant crossing way is larger than that of the capacitor pair formed by the comb-shaped capacitor plates distributed in the non-equidistant crossing way. The capacitance plate is opposite to the change of the effective area to cause the change of the capacitance value, the nonlinearity caused by the change of the distance between the capacitance plates is avoided, the position of the MEMS sensor is detected by comparing the sizes of the four capacitance values, the method is simple, and the experimental equipment is less. And the comb capacitor polar plates which are uniformly distributed simplify the manufacturing process.

Drawings

FIG. 1 is a top view of the apparatus of the present invention.

Fig. 2 is a flow chart of a process for manufacturing the device of fig. 1.

FIG. 3 is a three-dimensional schematic of the apparatus of the present invention.

Fig. 4 is a left side view of the device of the present invention.

Fig. 5 is a three-dimensional schematic view of a ring beam structure of the apparatus of the present invention.

FIG. 6 is a top view of the movable electrode and the fixed electrode of the device of the present invention.

FIG. 7 is a left side view of the movable electrode and the fixed electrode of the device of the present invention.

Fig. 8 is a partially enlarged plan view of the movable electrode and the fixed electrode of the device of the present invention.

FIG. 9 is a three-dimensional schematic of the device, micro-platform and MEMS sensor of the present invention.

The substrate 1, the central support platform 2, the ring-

shaped beams

3a, 3b, 3c and 3d, the

movable electrodes

4a, 4b, 4c and 4d, the

fixed electrodes

5a, 5b, 5c and 5d, the

anchor points

6a, 6b, 6c and 6d and 9a, 9b, 9c and 9d, the

cantilever beams

7a, 7b, 7c and 7d, the

inclined beams

8a, 8b, 8c and 8d, the straight beam 301 and the arc-shaped beam 302.

Detailed Description

The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings. The following examples are provided only for illustrating the present invention and are not intended to limit the scope of the present invention.

A position detection and calibration device for MEMS sensors, as shown in fig. 1, 3 and 4, is a centrosymmetric structure, comprising a substrate (1), a central support stage (2), movable electrodes (4a, 4b, 4c, 4d), fixed electrodes (5a, 5b, 5c, 5d), cantilever beams (7a, 7b, 7c, 7d), angled beams (8a, 8b, 8c, 8d) and ring beams (3a, 3b, 3c, 3 d). As shown in fig. 5, the ring beams (3a, 3b, 3c, 3d) are composed of two straight beams (301) and two arc beams (302) at the ends. The center supporting platform (2) is positioned in the center of the substrate (1), the centers of four sides of the center supporting platform (2) are connected with the movable electrodes (4a, 4b, 4c, 4d) through cantilever beams (7a, 7b, 7c, 7d), four corners of the center supporting platform (2) are connected with oblique beams (8a, 8b, 8c, 8d), the oblique beams (8a, 8b, 8c, 8d) are connected with the annular beams (3a, 3b, 3c, 3d), the other ends of the annular beams (3a, 3b, 3c, 3d) are fixed on the substrate (1) through aiming points (6a, 6b, 6c, 6d), the movable electrodes (4a, 4b, 4c, 4d) are opposite to the fixed electrodes (5a, 5b, 5c, 5d) to form comb-shaped capacitor pairs distributed at equal intervals in a crossing mode, and the fixed electrodes (5a, 5b, 5c, 5d) are arranged in a crossing mode, 5d) Are fixed on the substrate (1) by anchor points (9a, 9b, 9c, 9 d).

As shown in fig. 6 to 8, the movable electrodes (4a, 4B, 4c, 4d) and the fixed electrodes (5a, 5B, 5c, 5d) have the same thickness (F in fig. 7 represents the thickness), the comb-shaped capacitance plates of the movable electrodes (4a, 4B, 4c, 4d) and the comb-shaped capacitance plates of the fixed electrodes (5a, 5B, 5c, 5d) have the same pitch distribution (a in fig. 8 represents the distance), the size of each comb-shaped capacitance plate is the same (region represented by E in fig. 8), the comb-shaped capacitance plates of the movable electrodes (4a, 4B, 4c, 4d) and the comb-shaped capacitance plates of the fixed electrodes (5a, 5B, 5c, 5d) have the same pitch distribution (B in fig. 8), the comb-shaped capacitance plates of the movable electrodes (4a, 4B, 4c, 4d) and the fixed electrodes (5a, 5B, 5c, 5d) have the same pitch distribution (B represents the distance), and the comb-shaped capacitance plates of the movable electrodes (4a, 4B, 4c, 4d) and the fixed electrodes (5a), 5b, 5C, 5d) is equal to the distance from the comb-shaped capacitor plate of the fixed electrode (5a, 5b, 5C, 5d) to the movable electrode (4a, 4b, 4C, 4d) (distance represented by C in fig. 8). The product of the length (distance represented by D in fig. 8) of the overlapping portion of the comb-shaped capacitance plates of the movable electrodes (4a, 4b, 4c, 4D) and the comb-shaped capacitance plates of the fixed electrodes (5a, 5b, 5c, 5D) and the thickness of the overlapping portion is the effective facing area of the capacitance plates.

The substrate (1) is made of borosilicate glass, and the central support platform (2), the movable electrodes (4a, 4b, 4c, 4d), the fixed electrodes (5a, 5b, 5c, 5d), the cantilever beams (7a, 7b, 7c, 7d), the inclined beams (8a, 8b, 8c, 8d) and the annular beams (3a, 3b, 3c, 3d) are all made of monocrystalline silicon wafers.

The device is manufactured as shown in fig. 2 by the following steps:

(b) transferring the patterns of the suspended area, the central support platform (2), the movable electrodes (4a, 4b, 4c, 4d), the fixed electrodes (5a, 5b, 5c, 5d), the cantilever beams (7a, 7b, 7c, 7d), the inclined beams (8a, 8b, 8c, 8d) and the annular beams (3a, 3b, 3c, 3d) of the device to the back surface of a silicon chip by adopting a photoetching process; thinning the area to 200-300um by using a dry etching process, removing the photoresist and cleaning the silicon wafer; the suspended area is an area except for the substrate (1), the central support platform (2), the movable electrodes (4a, 4b, 4c, 4d), the fixed electrodes (5a, 5b, 5c, 5d), the cantilever beams (7a, 7b, 7c, 7d), the inclined beams (8a, 8b, 8c, 8d), the annular beams (3a, 3b, 3c, 3d) and the anchor points (6a, 6b, 6c, 6d, 9a, 9b, 9c, 9 d);

(d) preparing a smooth borosilicate glass substrate;

(g) transferring the patterns of the central support platform (2), the movable electrodes (4a, 4b, 4c, 4d), the fixed electrodes (5a, 5b, 5c, 5d), the cantilever beams (7a, 7b, 7c, 7d), the inclined beams (8a, 8b, 8c, 8d) and the annular beams (3a, 3b, 3c, 3d) of the device to the front surface of the silicon chip by adopting a photoetching process; sputtering a layer of metal aluminum electrode in the area by adopting a metal sputtering process, and cleaning a silicon wafer;

(i) after dicing, the preparation is completed.

The position detection and calibration of the MEMS sensor are carried out by utilizing the device, as shown in FIG. 9, the device is fixed at the central position of the micro platform, the MEMS sensor is placed at the center of the central support platform (2) of the device, a certain amount of volume load force downwards in the Z direction is applied to the central support platform (2) by avoiding the MEMS sensor, when the MEMS sensor is positioned at the central position of the central support platform (2), the movable electrodes (4a, 4b, 4c and 4d) generate equal downward displacement in the Z-axis direction, the movable electrodes (4a, 4b, 4c and 4d) respectively generate the same reduction value with the opposite effective area of the opposite fixed electrodes (5a, 5b, 5c and 5d), and the corresponding four capacitance values are changed identically; when the MEMS sensor deviates from the central position of the central support platform (2), the movable electrodes (4a, 4b, 4c and 4d) generate downward displacement in the unequal z-axis direction, and the effective facing areas of the movable electrodes (4a, 4b, 4c and 4d) and the opposite fixed electrodes (5a, 5b, 5c and 5d) respectively generate different reduction values, so that the corresponding four capacitance values are changed differently; the device is connected with an external processing circuit, converts the capacitance value into a voltage value, and judges the position of the MEMS sensor by comparing the four voltage values;

specifically, the device is fixed at the center of the micro platform, the MEMS sensor is placed in the center of a central support platform (2) of the device, and the MEMS sensor is avoided from exerting a certain volume load force F downwards in the Z direction on the central support platform (2). According to Newton' S second law, where F is force, m is mass, a is acceleration, and the relation between displacement and acceleration is 0.5at²Wherein S is displacement, t is time, when the center of the central support plate (2) of the MEMS sensor is deviated to the positive direction of the x axis, the mass of the positive direction of the x axis is larger than the mass of the negative direction of the x axis, and under the same volume loading force F, the downward acceleration of the Z direction of the positive direction of the x axis is smaller than the downward acceleration of the Z direction of the negative direction of the x axis, so that the downward displacement of the Z direction of the movable electrode (4c) of the positive direction of the x axis is smaller than the downward displacement of the Z direction of the movable electrode (4a) of the negative direction of the x axis, the positive effective area of the movable electrode (4c) of the positive direction of the x axis and the fixed electrode (5c) opposite to the movable electrode (4a) of the negative direction of the x axis is larger than the positive effective area of the movable electrode (5a) opposite to the movable electrode (4a) of the negative direction of the x axis, and the capacitance value is in positive proportion to the positive effective area, the capacitance value in the positive direction of the x axis is larger than the capacitance value in the negative direction of the x axis, the voltage value in the positive direction of the x axis is larger than the voltage value in the negative direction of the x axis, and when the absolute value of the difference value between the voltage value in the positive direction of the x axis and the voltage value in the negative direction of the x axis is larger, the MEMS sensor is far away from the central position of the central support platform (2); when the absolute value of the difference value between the voltage value in the positive direction of the x axis and the voltage value in the negative direction of the x axis becomes smaller, the MEMS sensor is close to the central position of the central support platform (2);

because the whole structure of the device is centrosymmetric, the same analysis is carried out in the y-axis direction: when the MEMS sensor is positioned at the center of a central supporting plate (2) of the device and is deviated to the positive direction of a y axis, the mass of the positive direction of the y axis is larger than the mass of the negative direction of the y axis, under the action of the same volume loading force F, the downward acceleration of the Z direction of the positive direction of the y axis is smaller than the downward acceleration of the Z direction of the negative direction of the y axis, so that the downward displacement of the Z direction of a movable electrode (4b) of the positive direction of the y axis is smaller than the downward displacement of the Z direction of a movable electrode (4d) of the negative direction of the y axis, the positive effective area of the movable electrode (4b) positioned at the positive direction of the y axis and a fixed electrode (5b) opposite to the movable electrode (4d) positioned at the negative direction of the y axis is larger than the positive effective area of the movable electrode (4d) positioned at the negative direction of the y axis and a fixed electrode (5d) opposite to the movable electrode (4d) positioned at the negative direction of the y axis, and the capacitance value is in positive proportion to the positive effective area, so that the positive direction of the y axis is larger than the capacitance value of the negative direction of the y axis, displaying that the voltage value in the positive direction of the y axis is larger than the voltage value in the negative direction of the y axis, and when the absolute value of the difference value between the voltage value in the positive direction of the y axis and the voltage value in the negative direction of the y axis is increased, the MEMS sensor is far away from the central position of the central support platform (2); when the absolute value of the difference value between the voltage value in the positive direction of the y axis and the voltage value in the negative direction of the y axis becomes smaller, the MEMS sensor is close to the central position of the central support platform (2);

when the MEMS sensor deviates from the central position of the central support platform (2), the position of the MEMS sensor is moved until the four voltage values are equal according to the magnitude and the variation of the four voltage values, and then the MEMS sensor is moved to the central position of the central support platform (2).

Claims

1. A position detection and calibration device for a MEMS sensor, characterized in that the device is a center-symmetric structure, comprising a substrate (1), a center support table (2), movable electrodes (4a, 4b, 4c, 4d), fixed electrodes (5a, 5b, 5c, 5d), cantilever beams (7a, 7b, 7c, 7d), inclined beams (8a, 8b, 8c, 8d) and ring beams (3a, 3b, 3c, 3d) ), the center support table (2) is located in the center of the substrate (1), and the center of the four sides of the center support table (2) is connected to the movable electrodes (4a, 4b, 4c, 4d) Connection, the four corners of the central support platform (2) are connected with inclined beams (8a, 8b, 8c, 8d), and the inclined beams (8a, 8b, 8c, 8d) are connected with the ring beams (3a, 3b, 3c, 3d), the other end of the annular beam (3a, 3b, 3c, 3d) is fixed on the base plate (1) through the aiming point (6a, 6b, 6c, 6d), and the movable electrodes (4a, 4b, 4c, 4d) are connected to the base plate (1). The fixed electrodes (5a, 5b, 5c, 5d) are opposite to each other, forming comb-tooth-shaped capacitor pairs with equal spacing and cross-distribution, and the fixed electrodes (5a, 5b, 5c, 5d) are fixed by anchor points (9a, 9b, 9c, 9d) on the substrate (1).

2. The position detection and calibration device for a MEMS sensor according to claim 1, wherein the annular beam (3a, 3b, 3c, 3d) is composed of two straight beams (301) and two at the end An arc beam (302) is formed.

3. The position detection and calibration device for a MEMS sensor according to claim 1, wherein the thickness of the movable electrodes (4a, 4b, 4c, 4d) and the fixed electrodes (5a, 5b, 5c, 5d) In the same way, the comb-shaped capacitor plates of the movable electrodes (4a, 4b, 4c, 4d) and the comb-shaped capacitor plates of the fixed electrodes (5a, 5b, 5c, 5d) are equally spaced and spaced equally. The size of each comb-shaped capacitor plate is the same, the comb-shaped capacitor plate of the movable electrode (4a, 4b, 4c, 4d) and the comb-shaped capacitor of the fixed electrode (5a, 5b, 5c, 5d) The pole plates are equally spaced and distributed, and the distances from the comb-shaped capacitive plates of the movable electrodes (4a, 4b, 4c, 4d) to the fixed electrodes (5a, 5b, 5c, 5d) and the distances from the fixed electrodes (5a, 5b, 5c) , 5d), the distances from the comb-shaped capacitive electrode plates to the movable electrodes (4a, 4b, 4c, 4d) are equal.

4. The position detection and calibration device for a MEMS sensor according to claim 1, wherein the substrate (1) is made of borosilicate glass, the center support table (2), the movable electrodes (4a, 4b, 4c) , 4d), fixed electrodes (5a, 5b, 5c, 5d), cantilever beams (7a, 7b, 7c, 7d), inclined beams (8a, 8b, 8c, 8d) and annular beams (3a, 3b, 3c, 3d) The materials are all monocrystalline silicon wafers.

5. The position detection and calibration device for MEMS sensor according to claim 1, wherein the device is made by the following steps:

(a) Prepare a single-crystal silicon wafer with a size of 4 inches polished on both sides;

(b) Using a photolithography process, the suspended area of the device, the central support table (2), the movable electrodes (4a, 4b, 4c, 4d), the fixed electrodes (5a, 5b, 5c, 5d), the cantilever beam (7a) , 7b, 7c, 7d), oblique beams (8a, 8b, 8c, 8d), and the patterns of annular beams (3a, 3b, 3c, 3d) are transferred to the back of the silicon wafer; the above areas are reduced by a dry etching process. Thin to 200-300um, remove the glue and clean the silicon wafer; the suspended area is the substrate (1), the central support table (2), the movable electrodes (4a, 4b, 4c, 4d), the fixed electrodes (5a, 5b, 5c, 5d), cantilever beams (7a, 7b, 7c, 7d), inclined beams (8a, 8b, 8c, 8d), ring beams (3a, 3b, 3c, 3d) and anchor points (6a, 6b, 6c) , 6d, 9a, 9b, 9c, 9d) outside the area;

(c) using wet etching process to remove the oxide film on the back of the silicon wafer;

(d) prepare a smooth borosilicate glass substrate;

(e) using a bonding process to make anchor points on the front side of the borosilicate glass substrate;

(f) bonding the back side of the silicon wafer and the front side of the borosilicate glass substrate together through anchor points, and cleaning the silicon wafer;

(g) adopt the photolithography process to set the device center support table (2), movable electrodes (4a, 4b, 4c, 4d), fixed electrodes (5a, 5b, 5c, 5d), cantilever beams (7a, 7b, 7c) , 7d), inclined beams (8a, 8b, 8c, 8d), and the patterns of annular beams (3a, 3b, 3c, 3d) are transferred to the front side of the silicon wafer; a metal sputtering process is used to sputter a layer of metal in the above area. Aluminum electrodes, and cleaning silicon wafers;

(h) using a photolithography process, the pattern of the suspended area of the device is transferred to the front side of the silicon wafer; using a dry etching process, the suspended area is etched through, and the glue is removed and the silicon wafer is cleaned;

(i) After dicing, the preparation is completed.

6. The position detection and calibration device for a MEMS sensor according to claim 1, wherein the device is used for position detection and calibration of the MEMS sensor, the device is fixed at the center position of the micro-platform, and the The MEMS sensor is placed in the center of the center support table (2) of the device, avoiding the MEMS sensor to apply a certain amount of downward volume load force in the Z direction to the center support table (2). When the MEMS sensor is located on the center support table (2) The center position of the movable electrodes (4a, 4b, 4c, 4d) produces an equal downward displacement in the z-axis direction, and the movable electrodes (4a, 4b, 4c, 4d) and the opposite fixed electrodes (5a, 5b, 5c) , 5d) produce the same reduction value, resulting in the same change in the corresponding four capacitance values; when the MEMS sensor deviates from the center position of the center support table (2), the movable electrodes (4a, 4b, 4c) , 4d) produce unequal downward displacement in the z-axis direction, and the positive effective areas of the movable electrodes (4a, 4b, 4c, 4d) and the opposite fixed electrodes (5a, 5b, 5c, 5d) have different reductions. small value, resulting in different changes in the corresponding four capacitance values; the device is connected to an external processing circuit, converts the capacitance value into a voltage value, and determines the position of the MEMS sensor by comparing the magnitudes of the four voltage values;

When the MEMS sensor deviates from the center position of the center support table (2), according to the magnitude and change of the four voltage values, move the position of the MEMS sensor until the four voltage values are equal, then the MEMS sensor moves to the center support table (2) the center position.

7. The position detection and calibration device for a MEMS sensor according to claim 6, characterized in that, when the MEMS sensor is located at the center of the center support plate (2) of the device and is deviated toward the positive direction of the x-axis, the positive direction of the x-axis is positive. The mass in the direction is greater than the mass in the negative direction of the x-axis. Under the same body load force, the downward acceleration in the Z-direction of the positive x-axis is smaller than the downward acceleration of the Z-direction in the negative direction of the x-axis. Therefore, the acceleration in the positive direction of the x-axis is The downward displacement of the movable electrode (4c) in the Z direction is smaller than the downward displacement in the Z direction of the movable electrode (4a) in the negative direction of the x-axis, resulting in the fixed position of the movable electrode (4c) in the positive direction of the x-axis. The positive effective area of the electrode (5c) is larger than the positive effective area of the movable electrode (4a) located in the negative direction of the x-axis and its opposite fixed electrode (5a). Since the capacitance value is proportional to the positive effective area, the x-axis The capacitance value in the positive direction is greater than the capacitance value in the negative direction of the x-axis, indicating that the voltage value in the positive direction of the x-axis is greater than the voltage value in the negative direction of the x-axis, when the difference between the voltage value in the positive direction of the x-axis and the voltage value in the negative direction of the x-axis When the absolute value of , the MEMS sensor is far from the center of the center support table (2); when the absolute value of the difference between the voltage value in the positive direction of the x-axis and the voltage value in the negative direction of the x-axis becomes small, the MEMS sensor is close to the center support the central position of the table (2);

Since the entire structure of the device is centrally symmetric, the same analysis can be done in the y-axis direction: when the MEMS sensor is located at the center of the central support plate (2) of the device and deviates toward the positive y-axis direction, the mass in the positive direction of the y-axis is greater than the y-axis. For the mass in the negative direction, under the same body load force, the downward acceleration in the Z direction in the positive y-axis direction is smaller than the downward acceleration in the Z direction in the negative y-axis direction, so the movable electrode in the positive y-axis direction (4b) The downward displacement in the Z direction is smaller than that of the movable electrode (4d) in the negative direction of the y-axis. For the effective area larger than the positive effective area of the movable electrode (4d) located in the negative direction of the y-axis and its opposite fixed electrode (5d), since the capacitance value is proportional to the positive effective area, the capacitance value in the positive direction of the y-axis is greater than The capacitance value in the negative direction of the y-axis shows that the voltage value in the positive direction of the y-axis is greater than the voltage value in the negative direction of the y-axis. When the absolute value of the difference between the voltage value in the positive direction of the y-axis and the voltage value in the negative direction of the y-axis becomes larger , the MEMS sensor is far from the center of the center support table (2); when the absolute value of the difference between the voltage value in the positive direction of the y-axis and the voltage value in the negative direction of the y-axis becomes smaller, the MEMS sensor is close to the center of the center support table (2) Location.