CN105137120B - A kind of V-beam torsional pendulum type single shaft micro-mechanical accelerometer and preparation method thereof - Google Patents

Abstract

The invention discloses a V-beam torsion pendulum single-axis micro-machine accelerometer and a preparation method thereof. The accelerometer includes a silicon sensitive structure and a glass substrate connected as one, and the silicon sensitive structure includes a fixed frame and a support integrated with the fixed frame. The beam and the sensitive mass assembly, the cross-section of the support beam is V-shaped, the sensitive mass assembly is fixed on the fixed frame through the support beam, the capacitor plate assembly and lead electrodes are arranged on the glass substrate, and the capacitor plate assembly is arranged on the sensitive mass assembly The lower part and the gap between the sensitive mass block components are arranged, and the lead electrodes are connected to the capacitor plate components; the preparation method includes two times of photolithography and two times of etching on the silicon wafer to prepare the silicon sensitive structure, and then bonding the silicon sensitive structure to the glass substrate to obtain V-beam torsional pendulum uniaxial micromachined accelerometer. The invention has the advantages of simple processing technology, high processing quality, good processing robustness, small cross-axis coupling error, good temperature characteristics and good stability.

Description

A V-beam torsional pendulum single-axis micromachined accelerometer and its preparation method

technical field

The invention relates to the field of micromechanical sensors, in particular to a V-beam torsional pendulum single-axis micromechanical accelerometer and a preparation method thereof.

Background technique

Accelerometers are mainly used to measure the motion parameters of moving objects relative to inertial space. Compared with traditional acceleration, MEMS micro-accelerometer technology has the characteristics of small size, low power consumption, and easy batch processing, so it quickly becomes a research hotspot, and its performance is constantly improving, and it is widely used in military and civilian fields.

At present, foreign uniaxial micro-accelerometer products have matured and been widely used. Domestic research and development of uniaxial micro-accelerometers are also increasing, and some laboratories have developed high-performance engineering. However, how to manufacture a single-axis micro-accelerometer with simple structure, high manufacturing efficiency and excellent performance in combination with the existing design process has important practical significance. Silicon micro-torsional accelerometers have a series of advantages such as small size, high reliability, and impact resistance, so they are widely valued by various countries, and they are competing to be developed. At present, they are gradually applied in the fields of guidance and vehicle inspection. However, the process is complicated, the noise is large, and the temperature characteristics and robustness are limited by its own structure.

The Chinese patent document with the patent application number 201410825011.3 discloses a micromechanical accelerometer, but the cross-section of the support beam of the sensitive mass assembly in this technical solution is hexagonal, which has cumbersome processing steps, robust processing, temperature characteristics, Capacitive sensitivity needs to be improved and other issues.

Contents of the invention

The technical problem to be solved by the present invention is to provide a V-shaped beam with simple processing technology, high processing quality, good processing robustness, small cross-axis coupling error, good temperature characteristics and good stability in view of the above problems in the prior art. A torsion-pendulum uniaxial micromachined accelerometer and a manufacturing method thereof.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A V-shaped beam torsional pendulum type uniaxial micromachined accelerometer, including a silicon sensitive structure and a glass substrate connected as one, the silicon sensitive structure includes a fixed frame, a support beam integrated with the fixed frame, and a sensitive mass assembly. The cross-section of the support beam is V-shaped, and the sensitive mass assembly is fixed on the fixed frame through the support beam; the capacitor plate assembly and lead electrodes are arranged on the glass substrate, and the capacitor plate assembly is arranged on the sensitive mass assembly The lead electrodes are connected with the capacitance plate assembly below and arranged in a gap with the sensitive mass assembly.

Preferably, the silicon-sensitive structure is made of a silicon wafer using a double-sided wet etching process, and the inner groove of the support beam is formed by wet etching a mask plate through the double-sided wet etching process The etched vacancies on both sides of the support beam are formed by wet etching with another mask plate of the double-sided wet etching process.

Preferably, the sensitive mass assembly includes two pairs of sensitive masses, each pair of sensitive masses includes a first sensitive mass and a second sensitive mass with different masses and arranged symmetrically with respect to the support beam, and the two pairs of sensitive The first sensitive mass of a pair of sensitive masses and the second sensitive mass of another pair of sensitive masses in the mass are located on the same side of the support beam; the capacitor plate assembly includes two first fixed capacitor plates and two The second fixed capacitance plate, the relative area of the first fixed capacitance plate and the first sensitive mass, and the relative area of the second fixed capacitance plate and the second sensitive mass are equal in size, and the first fixed capacitance plate is respectively Arranged under the first sensitive mass, the second fixed capacitance plates are respectively arranged under the second sensitive mass, the lead electrodes include a first electrode and a second electrode, and the two first fixed capacitance plates The two second fixed capacitor plates are connected by wires to form another group of detection capacitors and are drawn out from the second electrode. The difference between the two groups of detection capacitors is V-shaped. Output capacitance of a beam torsion-pendulum uniaxial micromachined accelerometer.

Preferably, the first sensitive mass and the second sensitive mass are respectively connected by a cantilever beam and a support beam, and the cantilever beam of the first sensitive mass in each pair of sensitive masses is opposite to the cantilever beam of the second sensitive mass The support beams are arranged symmetrically.

Preferably, the cross-sectional shape of the cantilever beam is trapezoidal.

Preferably, the first sensitive mass is connected to the cantilever beam through a midpoint of one side, and the second sensitive mass is connected to the cantilever beam through a midpoint of one side.

Preferably, both the first sensitive mass and the second sensitive mass are quadrangular pyramid-shaped structures, and the top surface of the quadrangular pyramid-shaped structure is arranged on the side close to the capacitor plate assembly, and the second Grooves are arranged on the larger bottom surface of the quadrangular pyramid-shaped structure on the sensitive mass.

Preferably, the glass substrate is provided with a pair of bonding bosses, and the fixed frame is provided with a pair of bonding anchor points, and anodic bonding is used for bonding between the bonding bosses and the bonding anchor points connection, the pair of bonded anchor points are symmetrically arranged in the middle of both sides of the fixed frame with the support beam as the center line.

Preferably, the silicon-sensitive structures are distributed symmetrically with respect to the structure center on the side opposite to the glass substrate.

The present invention also provides a method for preparing the aforementioned V-beam torsion-pendulum uniaxial micromechanical accelerometer, the steps of which include: 1) making a silicon wafer into a silicon-sensitive structure by using a double-sided wet etching process; 2) making the silicon-sensitive The structure is bonded to the glass substrate with the capacitive plate assembly and lead electrodes by anodic bonding to obtain a V-beam torsion-pendulum single-axis micromachined accelerometer; wherein the step 1) adopts a double-sided wet etching process The detailed steps to make a silicon wafer into a silicon-sensitive structure include:

1.1) Prepare a silicon wafer covered with a silicon dioxide layer;

1.2) Place a front mask on the front of the silicon wafer, perform photolithography and etch the silicon dioxide layer, and form a pre-buried layer mask pattern on the front of the silicon wafer, and the two positions of the pattern corresponding to the front mask The remaining thickness of the silicon oxide layer is the first thickness;

1.3) Place a reverse mask plate on the reverse side of the silicon wafer, perform photolithography and etch until the silicon surface is exposed, and form a mask pattern on the reverse side of the silicon wafer;

1.4) Remove all the photoresist from the silicon wafer and put it in the etching solution. When the silicon surface corresponding to the pattern position of the reverse mask is etched to the first depth, take it out of the etching solution;

1.5) Remove the first thickness of the silicon dioxide layer on the surface of the silicon wafer as a whole, so that the pattern position corresponding to the front mask is opened to expose the silicon surface;

1.6) Put the silicon wafer in the etching solution again, when the silicon surface corresponding to the pattern position of the reverse mask is etched and penetrated;

1.7) After removing all the silicon dioxide on the surface of the silicon wafer, a silicon-sensitive structure is obtained.

The V-beam torsional pendulum uniaxial micromechanical accelerometer of the present invention has the following advantages: (1) The silicon sensitive structure of the present invention includes a fixed frame, a support beam integrated with the fixed frame, and a sensitive mass assembly, and the transverse direction of the support beam The cross-section is V-shaped, so that the direction of the main axis of inertia of the support beam is transformed from a certain angle with the structure plane to perpendicular to the structure surface, which can reduce the output change caused by the mechanical creep caused by the structure itself, so that it can effectively improve Accelerometer stability; (2) The silicon sensitive structure of the present invention includes a fixed frame and a support beam integrated with the fixed frame and a sensitive mass assembly, and the cross section of the support beam is V-shaped, and the cross-section of the V-shaped support beam It is easy to process, and the process can be completed by two photolithography and two etching. Compared with the support beam with a hexagonal cross section, the process steps are simpler.

The preparation method of the V-shaped beam torsional pendulum type uniaxial micromachine accelerometer of the present invention can prepare the V-shaped beam torsion pendulum type uniaxial micromachined accelerometer of the present invention, and has the following advantages: (1) The V-shaped beam torsion pendulum type uniaxial micromechanical accelerometer of the present invention The preparation method of the micromachined accelerometer can be completed by using only two masks (front mask and back mask), including one front photolithography and one reverse photolithography, and since the single crystal silicon In the heterogeneous wet etching, the corrosion stops automatically when the surfaces intersect, so the processing of the inner support beam structure has good robustness, high processing precision and simple process. (2) In the preparation method of the V-beam torsion-pendulum uniaxial micromechanical accelerometer of the present invention, the front faces of the two pairs of sensitive mass blocks of the silicon sensitive structure are processed by the front mask, and the reverse is processed by the reverse mask. , so that the processing shape and structural design of the product are exactly the same, the processing accuracy is high, and the relative error of the capacitance of the silicon sensitive structure is smaller.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the front view of the embodiment of the present invention.

Fig. 2 is a schematic diagram of a three-dimensional exploded structure of an embodiment of the present invention.

FIG. 3 is a schematic diagram of a three-dimensional structure of a silicon-sensitive structure in an embodiment of the present invention.

FIG. 4 is a schematic top view of a silicon-sensitive structure in an embodiment of the present invention.

FIG. 5 is a schematic cross-sectional structure diagram of A-A in FIG. 4 .

Fig. 6 is a cross-sectional enlarged schematic diagram of a support beam in an embodiment of the present invention.

FIG. 7 is a schematic cross-sectional structure diagram of B-B in FIG. 4 .

FIG. 8 is a schematic structural view of a glass substrate in an embodiment of the present invention.

Fig. 9 is a schematic flow chart of the processing process of the embodiment of the present invention.

Fig. 10 is a schematic diagram of the movement direction of each mass block when the acceleration direction is vertical to the structural plane according to the embodiment of the present invention.

Fig. 11 is a schematic diagram of the movement direction of each sensitive mass when the acceleration direction is along the direction of the support beam in the structural plane according to the embodiment of the present invention.

Fig. 12 is a schematic diagram of the movement direction of each sensitive mass when the acceleration direction is the vertical support beam direction in the structural plane according to the embodiment of the present invention.

Fig. 13 is a schematic diagram of simulation of structural deformation distribution when the temperature rises according to an embodiment of the present invention.

FIG. 14 is a schematic diagram of a simulation of structural deformation distribution when the temperature is lowered according to an embodiment of the present invention.

Fig. 15 is a comparison chart of the output drift of the embodiment of the present invention and the prior art in the whole temperature range under the state of 0g.

Fig. 16 is a comparison chart of the variation of mechanical sensitivity in the whole temperature range under the state of 1 g in the embodiment of the present invention and the prior art.

Legend: 1. Glass substrate; 11. Capacitor plate assembly; 111. First fixed capacitor plate; 112. Second fixed capacitor plate; 12. Lead electrode; 121. First electrode; 122. Second electrode; 13. Key 2, silicon sensitive structure; 20, fixed frame; 21, support beam; 211, inner groove; 212, erosion space; 22, sensitive mass block assembly; 221, first sensitive mass block; Mass block; 223, cantilever beam; 224, groove; 23, bonding anchor point.

Detailed ways

As shown in Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5, the V-shaped beam torsion type uniaxial micromachined accelerometer of the present embodiment includes a silicon sensitive structure 2 and a glass substrate 1 connected as one, the silicon sensitive structure 2 includes a fixed frame 20, a support beam 21 integrated with the fixed frame 20, and a sensitive mass assembly 22. The cross section of the support beam 21 is V-shaped, and the sensitive mass assembly 22 is fixed on the fixed frame 20 through the support beam 21; the glass The substrate 1 is provided with a capacitive plate assembly 11 and lead electrodes 12 , the capacitive plate assembly 11 is disposed below the sensitive mass assembly 22 and arranged with a gap between the sensitive mass assembly 22 , and the lead electrodes 12 are connected to the capacitive plate assembly 11 . Since the cross-section of the support beam 21 in this embodiment is V-shaped, the controllability of the processing can be improved to improve the processing accuracy, so that the robustness of this embodiment is significantly improved. In this embodiment, the lead electrode 12 is specifically an electrode, and the fixing frame 20 of the silicon sensitive structure 2 is smaller than the glass substrate 1 , leaving a space for arranging the lead electrode 12 .

As shown in Figure 6, the silicon-sensitive structure 2 of this embodiment is made of a silicon wafer using a double-sided wet etching process, and the inner groove 211 of the support beam 21 is a mask plate through the double-sided wet etching process Formed by wet etching, the etched vacancies 212 on both sides of the support beam 21 are formed by wet etching with another mask plate of the double-sided wet etching process. The processing can be completed by photolithography and two times of etching. Compared with the support beam with a hexagonal cross section, it has the advantages of simple processing technology, high processing quality and good processing robustness; and the support beam 21 can be used in various Silicon microsensors, such as micromachined accelerometers, silicon gyroscopes, etc., can be used in beam structures for various purposes, such as resonant beams, support beams, etc., and have the advantage of a wide range of applications.

As shown in Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5, the sensitive mass block assembly 22 includes two pairs of sensitive mass blocks, and each pair of sensitive mass blocks includes different masses, the same size and symmetrically arranged relative to the support beam 21. The first sensitive mass 221 and the second sensitive mass 222, and the first sensitive mass 221 of a pair of sensitive masses in the two pairs of sensitive masses and the second sensitive mass 222 of another pair of sensitive masses are located on the support beam 21 on the same side; the capacitor plate assembly 11 includes two first fixed capacitor plates 111 and two second fixed capacitor plates 112, the relative area of the first fixed capacitor plate 111 and the first sensitive mass 221, the second fixed capacitor plate 112 and the relative area of the second sensitive mass 222 are equal in size, the first fixed capacitance plates 111 are respectively arranged under the first sensitive mass 221, and the second fixed capacitance plates 112 are respectively arranged on the sides of the second sensitive mass 222 Below, the lead electrode 12 includes a first electrode 121 and a second electrode 122. The two first fixed capacitance plates 111 are connected by wires to form a set of detection capacitances and share the first electrode 121. The two second fixed capacitance plates 112 are connected by wires. They are connected to form another group of detection capacitors and are led out from the second electrode 122 , and the difference between the two groups of detection capacitors is obtained to obtain the output capacitance of the V-beam torsion pendulum single-axis micromachined accelerometer. The structure of the sensitive mass assembly 22 has the following advantages: (1) Since the first sensitive mass 221 and the second sensitive mass 222 of this embodiment have different masses and the same size, and the capacitor plate assembly 11 includes two The first fixed capacitance plate 111 and two second fixed capacitance plates 112, the relative area of the first fixed capacitance plate 111 and the first sensitive mass 221, the relative area size of the second fixed capacitance plate 112 and the second sensitive mass 222 Equal, so it can ensure that the relative areas of the two sets of detection capacitors are the same to ensure the same capacitance. (2) The accelerometer disclosed in the Chinese patent document with the patent application number 201410825011.3 includes twelve fixed capacitance plates, and each sensitive mass corresponds to three fixed capacitance plates. Although the accelerometer can detect biaxial acceleration, the biaxial The mechanical sensitivity varies considerably. And the V-beam torsion pendulum uniaxial micromachined accelerometer of the present embodiment is a uniaxial accelerometer, and the capacitor plate assembly 11 includes two first fixed capacitor plates 111 and two second fixed capacitor plates 112, the first fixed capacitor plate 111 are respectively arranged under the first sensitive mass 221, and the second fixed capacitance plates 112 are respectively arranged under the second sensitive mass 222, that is, only one fixed capacitance plate is arranged under each sensitive mass, thereby effectively increasing the Capacitance sensitivity of large silicon sensitive structures 2. (3) The two first fixed capacitor plates 111 in this embodiment are connected by wires to form a set of detection capacitors and share the first electrode 121, and the two second fixed capacitor plates 112 are connected by wires to form another set of detection capacitors and shared The second electrode 122 is drawn out, and the two sets of detection capacitors output the output capacitance of the V-beam torsion pendulum single-axis micromachined accelerometer through the first electrode 121 and the second electrode 122 differentially, and the V-beam torsion pendulum single-axis accelerometer is obtained through the difference of the two detection capacitances. The output capacitance of the axial micromachined accelerometer can eliminate the impact of the displacement change of the sensitive mass under the influence of non-sensitive axis acceleration on the output of the accelerometer through differential action, which significantly improves stability and reduces external environmental changes such as temperature impact on output.

In this embodiment, both the first electrode 121 and the second electrode 122 are made of aluminum electrodes. Undoubtedly, the first electrode 121 and the second electrode 122 may also use other types of metal electrodes as required.

As shown in Fig. 1, Fig. 2, Fig. 3 and Fig. 4, the first sensitive mass 221 and the second sensitive mass 222 are connected to each other through the cantilever beam 223 and the support beam 21 respectively, and the first sensitive mass in each pair of sensitive masses The cantilever beam 223 of the block 221 and the cantilever beam 223 of the second sensitive mass 222 are arranged symmetrically with respect to the support beam 21 . Since the main axis of inertia of the support beam 21 is perpendicular to the structural surface, when bending deformation occurs, the displacement distribution of the first sensitive mass 221 and the second sensitive mass 222 in the same side area of the support beam 21 is along the direction of the side area and the support beam 21. The vertical center line is symmetrical, and the influence of the displacement change of the sensitive mass on the output of the accelerometer is eliminated through the differential action, which further improves the stability and reduces the influence of external environment changes such as temperature on the output. Advantages of good characteristics.

As shown in FIG. 7 , the cross-sectional shape of the cantilever beam 223 is trapezoidal. Under the influence of temperature or acceleration in the direction of the unsupported beam 21, the cantilever beam 223 with a trapezoidal cross-section can further eliminate the torsion of the overall structure, make the structural displacement distribution even, and reduce the influence of the torsion of the fixed frame 20 on the output.

As shown in Figure 1, Figure 2, Figure 3 and Figure 4, the first sensitive mass 221 is connected to the cantilever beam 223 through the midpoint of a side, and the second sensitive mass 222 is connected to the cantilever beam through the midpoint of a side 223 , this structure can ensure uniform force distribution between both the first sensitive mass 221 and the second sensitive mass 222 and the cantilever beam 223 .

As shown in FIG. 5 , the first sensitive mass 221 and the second sensitive mass 222 are rectangular pyramid-shaped structures, and the top surface of the quadrangular pyramid-shaped structure is arranged on the side close to the capacitor plate assembly 11. The sensitive mass 222 is provided with a groove 224 on the larger bottom surface of the quadrangular pyramid structure. The groove 224 is easy to process, and can realize the mass difference between the first sensitive mass 221 and the second sensitive mass 222 simply and conveniently.

As shown in Fig. 1, Fig. 2, Fig. 3 and Fig. 4, a pair of bonding bosses 13 are arranged on the glass substrate 1, and a pair of bonding anchor points 23 are arranged on the fixed frame 20, and the bonding bosses 13 and the bonding anchors Anodic bonding is used between the points 23 for bonding connection. Adopting the anodic bonding method for bonding connection can realize the connection between the glass substrate 1 and the fixed frame 20 conveniently and quickly, and the process is simple and the operation is convenient.

As shown in Figure 1, Figure 2, Figure 3 and Figure 4, the side of the silicon sensitive structure 2 opposite to the glass substrate 1 is fully symmetrically distributed with the structure center, which can reduce the two pairs of sensitive masses of the fixed frame 20 and the bonding anchor point 23 Effect of Block Sensitivity.

As shown in FIG. 8 , the capacitive plate assembly 11 in this embodiment includes four fixed capacitive plates, wherein the two first fixed capacitive plates 111 are respectively marked as b and c, and the two second fixed capacitive plates 112 are respectively marked as a and d. The two pairs of sensitive masses convert the input acceleration into inertial force, and the inertial force causes the displacement of the two pairs of sensitive masses, so that the capacitance between the two pairs of sensitive masses and the capacitor plate assembly 11 changes, and because each pair of sensitive masses Due to the mass asymmetry between the first sensitive mass 221 and the second sensitive mass 222 in the mass, when subjected to an acceleration perpendicular to the surface of the silicon structure, the support beam 21 is twisted, and the two first fixed capacitance plates 111 ( b and c) are connected by wires to form a set of detection capacitances, and two second fixed capacitance plates 112 (a and d) are connected by wires to form another set of detection capacitance differences, to obtain the capacitance output under the action of the acceleration in this direction, through the external The capacitance detection circuit can obtain the capacitance output value, and then calculate the corresponding acceleration.

As shown in Figure 9, the steps of the manufacturing method of the V-beam torsion-pendulum uniaxial micromachined accelerometer in this embodiment include: 1) Using a double-sided wet etching process to make a silicon wafer into a silicon-sensitive structure 2; 2) The silicon sensitive structure 2 is bonded to the glass substrate 1 with the capacitive plate assembly 11 and the lead electrode 12 by anodic bonding to obtain a V-beam torsion pendulum single-axis micromachined accelerometer; wherein the step 1) adopts The detailed steps of making a silicon wafer into a silicon-sensitive structure 2 by a double-sided wet etching process include:

1.1) Prepare a silicon wafer covered with a silicon dioxide layer; as shown in Figure 9(a); in this embodiment, the thickness of the silicon wafer is 240 microns, and the thickness of the silicon dioxide is 400 nm;

1.2) Place a front mask on the front of the silicon wafer, perform photolithography and etch the silicon dioxide layer, and form a pre-buried layer mask pattern on the front of the silicon wafer, and the two positions of the pattern corresponding to the front mask The remaining thickness of the silicon oxide layer is the first thickness, and the structure of the silicon wafer at this time is shown in Figure 9(b); in this embodiment, the first thickness is specifically 200nm;

1.3) Place a reverse mask on the back of the silicon wafer, perform photolithography and etch until the silicon surface is exposed, and form a mask pattern on the back of the silicon wafer. The structure of the silicon wafer at this time is shown in Figure 9(c) ;

1.4) Remove all the photoresist from the silicon wafer and put it in the etching solution. When the silicon surface corresponding to the pattern position of the reverse mask is etched to the first depth, it is taken out from the etching solution. At this time, the structure of the silicon wafer is As shown in Figure 9(d); in this embodiment, the first depth is specifically 20 microns, and the etching solution is specifically TMAH solution;

1.5) Remove the first thickness of the silicon dioxide layer on the surface of the silicon wafer as a whole (ie 200nm), so that the pattern position corresponding to the front mask is opened to expose the silicon surface. At this time, the structure of the silicon wafer is shown in Figure 9 (e );

1.6) Place the silicon wafer in the etching solution again. When the etching depth is about 180 microns, due to the small corrosion rate of the crystal plane, the corrosion at the junction of the two crystal planes stops automatically, forming a V-shaped support in cross section. The inner groove 211 of the beam 21, at this time, the structure of the silicon wafer is shown in Figure 9(f); continue to etch the silicon wafer, when the silicon surface at the pattern position corresponding to the mask plate on the reverse side is etched and penetrated, forming a cross section of The erosion vacancies 212 on both sides of the V-shaped support beam 21, at this time, the structure of the silicon wafer is shown in FIG. 9(g);

1.7) The silicon-sensitive structure 2 is obtained after all the silicon dioxide on the surface of the silicon wafer is removed.

Finally, the silicon sensitive structure 2 is bonded to the glass substrate 1 with the capacitive plate assembly 11 and the lead electrodes 12 by anodic bonding to obtain a V-beam torsional pendulum uniaxial micromechanical accelerometer, as shown in Fig. 9(h) Show.

By using ANSYS software to simulate the displacement of each sensitive mass under acceleration in different directions and the displacement of each sensitive mass when the temperature changes, the simulation results of the V-beam torsion-pendulum uniaxial micromachined accelerometer of this embodiment are obtained as shown in Figure 10-Fig. 14.

Referring to Fig. 10, Fig. 11 and Fig. 12, a represents acceleration, and the arrow next to a represents the direction of acceleration; the arrow on the sensitive mass (the first sensitive mass 221 or the second sensitive mass 222) represents the force affected by this direction. The direction of motion of the sensitive mass during acceleration. Referring to Fig. 10, when the acceleration direction is vertical to the structural plane, the support beam 21 is dominated by torsional deformation, and the acceleration direction at this time is the detection direction of the uniaxial accelerometer in this embodiment; see Fig. 11 and Fig. 12, when subjected to structural During the acceleration along the direction of the support beam 21 and the direction perpendicular to the support beam 21 in the plane, the support beam 21 is mainly bent and deformed. At this time, the sensitive mass is in the two areas with the support beam 21 as the boundary, and the first in the same area The displacement between the sensitive mass 221 and the second sensitive mass 222 is the same, because the accelerometer is a double differential detection, so the output caused by the displacement in the vertical direction of the structure plane is eliminated by the differential effect.

13 and 14 respectively simulate the displacement distribution of the silicon sensitive structure 2 when the V-beam torsion pendulum uniaxial micromachined accelerometer of this embodiment is not affected by acceleration and the temperature rises and falls. In the figure, T represents temperature, and the rising or falling arrows next to T represent temperature rise and fall, the numbers 1, 2, 3, and 4 represent the numbers of the sensitive masses, and the arrows on the sensitive masses represent the movement directions of the sensitive masses. It can be seen from Fig. 13 and Fig. 14 that since this embodiment adopts a V-shaped beam structure (that is, the cross section of the support beam 21 is V-shaped), under the influence of temperature T, the overall deformation of the fixed frame 20 in this embodiment is caused by The displacement is also distributed symmetrically, which avoids the output error caused by the deflection of the fixed frame 20; while the sensitive mass is in the two areas separated by the support beam 21, the displacement of the sensitive mass in the same area is along the direction of the bonding anchor point 23. The wiring direction is distributed symmetrically, so the output drift of the accelerometer caused by the temperature change can be eliminated through the differential action.

Referring to Fig. 15 and Fig. 16, the V-beam torsional pendulum uniaxial micromachined accelerometer of this embodiment and the prior art (the technical solution recorded in Chinese patent application No. 201410825011.3) are simulated in the full temperature zone ( -40°C to +60°C) accelerometer offset drift versus mechanical sensitivity change (expressed in capacitance form). It can be seen from Figure 15 (acceleration 0g) and Figure 16 (acceleration 1g) that the zero-bias and full-temperature range offset of the prior art is 13.07 mg, while the V-beam torsion pendulum single-axis micromachine of this embodiment The zero-bias full-temperature zone offset of the accelerometer is 3.14mg, and the change value of the mechanical sensitivity full-temperature zone of the prior art is 0.88fF, while the mechanical sensitivity full-temperature zone of the V-shaped beam torsion pendulum type uniaxial micromachined accelerometer of the present embodiment is The range change value is 0.25fF. Therefore, compared with the prior art, the zero-bias full-temperature zone offset and the mechanical sensitivity full-temperature zone change value of the V-beam torsion-pendulum uniaxial micromachined accelerometer in this embodiment are greatly reduced at the same time. The temperature characteristics of the accelerometer are significantly improved, that is, the stability of the entire temperature zone is improved, the temperature sensitivity of the scaling factor is reduced, and the two key performance indicators of the accelerometer are comprehensively improved.

The above descriptions are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principles of the present invention should also be regarded as the protection scope of the present invention.

Claims (9)

1. A kind of 1. V-beam torsional pendulum type single shaft micro-mechanical accelerometer, it is characterised in that：Including the silicon-sensitive structure being connected as one （2）And glass substrate（1）, the silicon-sensitive structure（2）Including fixed frame（20）And and fixed frame（20）Form one Supporting beam（21）And sensitive-mass block assembly（22）, the supporting beam（21）Cross section be V-arrangement, the sensitive-mass block Component（22）Pass through supporting beam（21）It is fixed on fixed frame（20）On；The glass substrate（1）It is equipped with capacitor board component （11）With lead electrode（12）, the capacitor board component（11）Arranged on sensitive-mass block assembly（22）Lower section and with sensitive-mass block Component（22）Gap arrangement, the lead electrode（12）With capacitor board component（11）It is connected；The sensitive-mass block assembly（22） Including two pairs of sensitive-mass blocks, quality difference and opposite supporting beam are included per a pair of sensitive-mass block（21）First be arranged symmetrically Sensitive-mass block（221）With the second sensitive-mass block（222）, and in two pairs of sensitive-mass blocks a pair of of sensitive-mass block the One sensitive-mass block（221）With the second sensitive-mass block of another pair sensitive-mass block（222）Positioned at supporting beam（21）It is same Side；The capacitor board component（11）Including two the first fixed capacity plates（111）With two the second fixed capacity plates（112）, institute State the first fixed capacity plate（111）With the first sensitive-mass block（221）Relative area, the second fixed capacity plate（112）With Two sensitive-mass blocks（222）Relative area between equal in magnitude, the first fixed capacity plate（111）It is respectively arranged in first Sensitive-mass block（221）Lower section, the second fixed capacity plate（112）It is respectively arranged in the second sensitive-mass block（222）'s Lower section, the lead electrode（12）Including first electrode（121）And second electrode（122）, described two first fixed capacity plates （111）It is connected by conducting wire and forms one group of detection capacitance and shared first electrode（121）Draw, described two second fixed capacities Plate（112）It is connected by conducting wire and forms another group of detection capacitance and shared second electrode（122）Draw, capacitance is detected described in two groups Difference obtains the output capacitance of V-beam torsional pendulum type single shaft micro-mechanical accelerometer.
2. 2. V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to claim 1, it is characterised in that：The silicon-sensitive Structure（2）It is made of silicon wafer of two-sided wet etching processing technology, the supporting beam（21）Inside groove（211）For by double One piece of mask plate of face wet etching processing technology carries out wet etching and processes to be formed, the supporting beam（21）The erosion room of both sides （212）To be formed to be processed by another piece of mask plate of two-sided wet etching processing technology progress wet etching.
3. 3. V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to claim 2, it is characterised in that：Described first is quick Feel mass block（221）With the second sensitive-mass block（222）Pass through cantilever beam respectively（223）And supporting beam（21）It is connected, per a pair of First sensitive-mass block in sensitive-mass block（221）Cantilever beam（223）With the second sensitive-mass block（222）Cantilever beam （223）With respect to supporting beam（21）It is arranged symmetrically.
4. 4. V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to claim 3, it is characterised in that：The cantilever beam （223）Shape of cross section to be trapezoidal.
5. 5. V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to claim 4, it is characterised in that：Described first is quick Feel mass block（221）Midpoint and cantilever beam by side（223）It is connected, the second sensitive-mass block（222）Pass through The midpoint of one side and cantilever beam（223）It is connected.
6. 6. V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to claim 5, it is characterised in that：Described first is quick Feel mass block（221）With the second sensitive-mass block（222）It is tetrapyamid shape structure, the tetrapyamid shape structure product is smaller Top surface be arranged in by capacitor board component（11）Side, the second sensitive-mass block（222）It is upper to be located at tetrapyamid shape structure The larger bottom surface of upper area is equipped with groove（224）.
7. 7. the V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to any one in claim 1~6, its feature exist In：The glass substrate（1）It is equipped with a pair of of bonding boss（13）, the fixed frame（20）It is equipped with a pair of of bonding anchor point （23）, the bonding boss（13）With bonding anchor point（23）Between bonding connection carried out using anode linkage mode；It is the pair of It is bonded anchor point（23）With supporting beam（21）Fixed frame is symmetrically arranged in for center line（20）Both sides middle part.
8. 8. V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to claim 7, it is characterised in that：The silicon-sensitive Structure（2）With respect to glass substrate（1）Side with structure centre in holohedral symmetry be distributed.
9. 9. the preparation side of the V-beam torsional pendulum type single shaft micro-mechanical accelerometer according to any one in claim 1~8 Method, step include：1）Silicon wafer is made by silicon-sensitive structure using two-sided wet etching processing technology（2）；2）By silicon-sensitive knot Structure（2）With with capacitor board component（11）With lead electrode（12）Glass substrate（1）It is bonded using anode linkage mode, Obtain V-beam torsional pendulum type single shaft micro-mechanical accelerometer；Wherein described step 1）It is middle to use two-sided wet etching processing technology Silicon-sensitive structure is made in silicon wafer（2）Detailed step include：

   1.1）Prepare silicon wafer of the surface covered with silicon dioxide layer；

   1.2）Front mask plate is placed in the front of silicon wafer, photoetching is carried out and corrodes silicon dioxide layer, in the front of silicon wafer Form pre- buried regions mask pattern, the thickness of the silicon dioxide layer of the corresponding pattern position of the front mask plate is thick remaining as first Degree；

   1.3）Reverse side mask plate is placed in the reverse side of silicon wafer, photoetching is carried out and corrodes to silicon face is exposed, in the anti-of silicon wafer Face forms mask pattern；

   1.4）Silicon wafer is removed whole photoresists to be placed in etchant solution, when the silicon of the corresponding pattern position of reverse side mask plate Taken out after being etched to the first depth from etchant solution on surface；

   1.5）Silicon dioxide layer whole removing on silicon wafer surface is removed into first thickness so that the corresponding pattern position of front mask plate Put to be opened and expose silicon face；

   1.6）Silicon wafer is again placed in etchant solution, is worn when the silicon face of the corresponding pattern position of reverse side mask plate is corroded Thoroughly；

   1.7）Silicon-sensitive structure is obtained after the silica on silicon wafer surface is all removed（2）.