Omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer and its processing method

Abstract

The present invention discloses an omnidirectional dynamic heat source pendulum type biaxial micromechanical accelerometer and a processing method thereof. The biaxial accelerometer comprises a base layer, a sensitive layer and a cover plate. The sensitive layer contains an intermediate heating cavity and an intermediate detection cavity. The upper surface of the sensitive layer is provided with an omnidirectional dynamic heat source pendulum heater and two pairs of thermistors; the omnidirectional dynamic heat source pendulum heater is suspended at the center of the sensitive layer through six completely symmetrical semicircular support beams; the heater is powered by constant current; a groove is etched on the cover plate and is tightly connected to the upper surface of the sensitive layer. The present invention can realize the measurement of biaxial acceleration, has high sensitivity, fast response speed, has the characteristics of small structural stress, small size, light weight, easy intelligence and integration, and conforms to the development direction of sensors towards micro, comprehensive and intelligent types. At the same time, it has the advantages of very simple structure and processing technology, extremely low cost, high reliability, excellent anti-vibration and impact characteristics, etc.

Description

Technical Field

[0001] The present invention relates to a technical field of utilizing an omnidirectional dynamic heat source pendulum to swing under the action of linear acceleration to detect acceleration attitude parameters of a moving carrier, and in particular to an omnidirectional dynamic heat source pendulum-type dual-axis micromechanical accelerometer and a processing method thereof, belonging to the field of inertial measurement. Background Art

[0002] Due to the application demand of carrier attitude measurement in various fields such as civil vehicles, railway construction, industrial production, bridge construction, earthquake research, geodetic mapping, geological and mineral exploration, marine survey, satellite communication, robotics engineering, etc., in recent years, the organic combination of sensor technology and emerging science and technology will make attitude sensors develop in the direction of miniature, comprehensive and intelligent. Micro inertial sensors made by MEMS (Micro-Electro-Mechanical-System) technology have many advantages such as mass production, low cost, small size and low power consumption. They are ideal products for medium and low precision micro inertial sensors in the future. Accelerometers are the core inertial sensors for carrier motion attitude measurement and control.

[0003] The most commonly used accelerometer is the pendulum accelerometer. Currently, the commonly used pendulum inclination sensors are liquid pendulum, solid pendulum and heat flow. The solid pendulum inclination sensor has a complex structure and high cost. The solid pendulum has a large movement amplitude and is difficult to withstand high overload or impact. The main problem of the liquid pendulum inclination sensor is that it has many structural components, long response time, and large performance changes with temperature. The heat flow accelerometer has a small sensitive mass, a simple structure, and has the characteristics of withstanding high overload, short response time, good temperature performance and low cost, and can be used in harsh environments. At present, the market has higher and higher requirements for the ability of micro accelerometers to adapt to harsh and harsh environments. Therefore, among micro accelerometers, micromechanical (MEMS) heat flow accelerometers are unique in MEMS sensors with their ultra-high impact resistance and ultra-low manufacturing cost, which is unmatched by other MEMS accelerometers.

[0004] The working principle of the micro-machined (MEMS) heat flow accelerometer is: a resistive heater is set in a closed cavity, and symmetrically distributed parallel detection thermistors are set around it. The heater is powered on to heat to form a heat source that emits heat flow to the surrounding area. Since the temperature field is symmetrically distributed, the influence on the thermistors is consistent. When external wired acceleration is input, the flow direction of the hot air flow is the same as the acceleration direction, and changes in the direction of the input acceleration, causing the temperature field of the air flow to be asymmetrically distributed, so that the temperature changes of two adjacent detection thermistors in the same direction are opposite, and the two detection thermistors produce a temperature difference. Acceleration detection can be achieved by detecting the temperature difference through a Wheatstone bridge. The micro-machined heat flow accelerometers in the Chinese patent: Micro silicon bridge thermal convection accelerometer (patent application number 02116842.3) and the Chinese patent micro heat flow accelerometer and its manufacturing method (patent application number 03143287.6) both use the heat flow generated by the heater to move under the action of the input wire acceleration, resulting in an asymmetric temperature field, and the asymmetric distribution of the temperature field is detected by setting symmetrical thermistors. Since the speed of the thermal airflow is very small, the asymmetric temperature field gradient caused by the airflow deflection is very small, so the unbalanced voltage output by the Wheatstone bridge composed of thermistors is small and the sensitivity of the sensor is low. In the existing solutions, although the sensitivity can be improved by increasing the power of the heater, it is limited by power consumption and there is no substantial change or improvement in sensitivity, making it difficult to break through this practical bottleneck. Summary of the invention

[0005] The purpose of the present invention is to provide an omnidirectional dynamic heat source pendulum type dual-axis micromechanical accelerometer to solve the technical problems existing in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides an omnidirectional dynamic heat source pendulum type dual-axis micromechanical accelerometer, comprising a base layer, a sensitive layer and a cover plate, wherein:

[0008] The sensitive layer comprises a middle heating cavity and a middle detection cavity, and an omnidirectional dynamic heat source swing heater and two pairs of thermistors are arranged on the upper surface of the sensitive layer; the length direction of the upper surface of the sensitive layer is defined as the X direction, the width is defined as the Y direction, and the height direction is defined as the Z direction; the two pairs of thermistors are placed in the X direction and the Y direction, and each pair of thermistors are parallel to each other, and are used to detect the acceleration of the X axis and the Y axis;

[0009] The omnidirectional dynamic heat source pendulum heater adopts a Hot Wheels sensitive structure, the center of which contains a central wheel hub with a circular mass block, which is suspended at the center of the sensitive layer through six completely symmetrical semicircular beams, also called support beams; below it is a circular intermediate heating cavity;

[0010] The omnidirectional dynamic heat source swing heater can not only swing along the z-axis perpendicular to the sensitive layer, but also swing along any azimuth angle in the XOY plane where the sensitive layer is located.

[0011] The two ends of the omnidirectional dynamic heat source pendulum heater cover symmetrical electrodes along the Y direction to form a movable resistive heat source;

[0012] The thermistor includes a pair of thermistors for detecting X-axis acceleration and a pair of thermistors for detecting Y-axis acceleration, and a rectangular middle detection cavity is located below the thermistors;

[0013] A pair of thermistors for detecting the acceleration of the X-axis are placed symmetrically along the Y-axis direction and perpendicular to the X-axis direction; a pair of thermistors for detecting the acceleration of the Y-axis are placed symmetrically along the X-axis direction and perpendicular to the Y-axis direction;

[0014] The omnidirectional dynamic heat source pendulum heater and thermistor are powered by constant current;

[0015] A groove is etched on the cover plate and is tightly connected to the upper surface of the sensitive layer.

[0016] The cover plate and the base layer isolate the gas medium of the middle heating cavity and the middle detection cavity from the outside world to form a sealed working system; the height of the middle heating cavity and the middle detection cavity and the depth of the groove in the upper sealing layer are the total cavity height z, 300μm≤z≤1000μm.

[0017] As a further technical solution, the depth of the groove of the cover plate is 2 / 3 of the height of the cover plate.

[0018] As a further technical solution, the height of the omnidirectional dynamic heat source pendulum heater and the thermistor is 100nm to 1000nm.

[0019] As a further technical solution, the two pairs of thermistors have the same length, which is 1 / 6 to 1 / 5 of the width of the entire sensitive layer.

[0020] As a further technical solution, the heater and the thermistor are both composed of a metal layer consisting of a chromium adhesion layer and a platinum layer.

[0021] A method for processing an omnidirectional dynamic heat source pendulum-type dual-axis micromechanical accelerometer, the specific process flow is as follows:

[0022] Step 1: thermally oxidize a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer;

[0023] Step 2: Photolithography forms a full-range dynamic heat source swing heater and a thermistor structure pattern on the silicon dioxide film;

[0024] Step 3: sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and silicon dioxide in sequence by using a magnetron sputtering process;

[0025] Step 4: Use ultrasonic stripping process to strip off the metal layer outside the omnidirectional dynamic heat source pendulum heater and thermistor structure pattern to form the omnidirectional dynamic heat source pendulum heater and thermistor structure;

[0026] Step 5: Use photolithography and wet etching process to etch away a portion of silicon dioxide;

[0027] Step 6: Use silicon etching process to form a groove with a depth of 300 μm, so that the omnidirectional dynamic heat source pendulum heater and thermistor are suspended and fixed on the sensitive layer through the silicon dioxide film, and the processing of the accelerometer sensitive layer is completed;

[0028] Step seven: The cover plate and the sensitive layer are bonded by a bonding process so that the upper surface of the sensitive layer is in a closed cavity to complete the processing of the accelerometer sensitive element and form an omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer.

[0029] By adopting the above technical solution, the present invention has the following beneficial effects:

[0030] 1. This omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer inherits the advantages of MEMS heat flow accelerometer, with small size, light weight, and easy intelligence and integration.

[0031] 2. The sensitive structure of this accelerometer is the omnidirectional dynamic heat source pendulum heater in the middle. In addition to being able to swing up and down along the z-axis perpendicular to the plane of the sensitive layer, this omnidirectional dynamic heat source pendulum has the freedom (swing) of inertial force at any azimuth angle on the XOY plane of the sensitive layer. The sensitive structure is suspended at the center of the sensitive layer through six completely symmetrical semicircular support beams, and can sense the input acceleration along the X-axis or Y-axis, thereby realizing the measurement of dual-axis acceleration, with high sensitivity and fast response speed.

[0032] 3. This omnidirectional vibrator adopts a Hot Wheels-style sensitive structure, and the central wheel hub is a mass block and also a heater. This Hot Wheels-style sensitive structure has the following advantages: it adopts a central support of the sensitive structure, and the structural stress is small; it has high structural symmetry and can achieve consistency in azimuth angle detection; the Hot Wheels-style sensitive structure can realize the production of relatively long elastic elements and relatively large mass blocks in a small area, thereby obtaining a large inertial force sensitivity. 4. The sensitive element is made on a silicon wafer through photolithography, corrosion and other processes, with good consistency, which is convenient for introducing a microcomputer embedded system (single-chip microcomputer) for temperature compensation and nonlinearity compensation, which can not only improve the performance of the sensor, but also realize mass production.

[0033] 5. It has the advantages of very simple structure and processing technology, extremely low cost, high reliability, and excellent anti-vibration and impact characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of a three-dimensional structure of a sensitive layer provided in an embodiment of the present invention;

[0036] Figure 2 A schematic diagram of a three-dimensional structure of a cover plate provided in an embodiment of the present invention;

[0037] Figure 3 A top view of a sensitive layer provided by an embodiment of the present invention;

[0038] Figure 4 for Figure 3 AA section view;

[0039] Figure 5 A working principle diagram provided for an embodiment of the present invention;

[0040] Figure 6 A schematic diagram of an output circuit provided by an embodiment of the present invention;

[0041] Figure 7 A flow chart of the preparation process of an omnidirectional dynamic heat source pendulum-type dual-axis micromechanical accelerometer provided in an embodiment of the present invention;

[0042] Icon: 1-base layer, 2-sensitive layer, 3-middle detection cavity, 4-middle heating cavity, 5-cover plate, 6-groove, 7-all-round dynamic heat source swing heater, 8-thermistor, 9-thermistor, 10-thermistor, 11-thermistor, 12-metal electrode. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0047] Combination Figure 1-4 As shown, this embodiment provides an omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer, including a substrate 1, a sensitive layer 2 and a cover plate 5, wherein:

[0048] The sensitive layer 2 comprises an intermediate heating cavity 4 and an intermediate detection cavity 3, and an omnidirectional dynamic heat source swing heater 7 and two pairs of thermistors are arranged on the upper surface of the sensitive layer;

[0049] The length direction of the upper surface of the sensitive layer is defined as the X direction, the width is defined as the Y direction, and the height direction is defined as the Z direction; the two pairs of thermistors are defined as the X direction and the Y direction, and each pair of thermistors are parallel to each other, and are used to detect the acceleration of the X axis and the Y axis; the omnidirectional dynamic heat source pendulum heater 7 adopts a Hot Wheels sensitive structure, the center of which contains a central wheel hub with a circular mass block, which is suspended at the center of the sensitive layer through six completely symmetrical semicircular support beams; below it is a circular intermediate heating chamber 4;

[0050] The omnidirectional dynamic heat source swing heater 7 can not only swing along the z-axis perpendicular to the sensitive layer, but also swing along any azimuth angle in the XOY plane where the sensitive layer is located.

[0051] Both ends of the omnidirectional dynamic heat source swing heater are covered with symmetrical metal electrodes 12 along the Y direction to form a movable resistive heat source;

[0052] The thermistor includes a pair of thermistors (thermistor 8 and thermistor 10) for detecting X-axis acceleration and a pair of thermistors (thermistor 9 and thermistor 11) for detecting Y-axis acceleration, and a rectangular middle detection cavity 3 is located below the thermistors;

[0053] Thermistors 8 and 10 for detecting X-axis acceleration are placed in parallel on both sides of the upper surface of the sensitive layer in the Y direction, and thermistors 9 and 11 for detecting Y-axis acceleration are placed in parallel on both sides of the upper surface of the sensitive layer in the X direction;

[0054] The omnidirectional dynamic heat source pendulum heater 7 and the thermistor are both powered by constant current;

[0055] The cover plate 5 is etched with a groove 6 and is tightly connected to the upper surface of the sensitive layer 2;

[0056] In this embodiment, as a further technical solution, the omnidirectional dynamic heat source pendulum heater 7 can be sensitive to input acceleration along any azimuth angle of the X-axis or Y-axis in the XOY plane, thereby realizing the measurement of dual-axis acceleration.

[0057] In this embodiment, as a further technical solution, a constant current is passed through the omnidirectional dynamic heat source swing heater 7, and the resistance heater is energized to generate Joule heat, release heat to the surrounding gas, perform heat diffusion, and form a heat flow around it. The temperature field generated by the heat flow is symmetrically distributed between two thermistors (thermistor 8 and thermistor 10 or thermistor 9 and thermistor 11) in the same direction.

[0058] Combination Figure 5 As shown, when the input is a linear acceleration input along the X or Y axis X or a Y When the omnidirectional moving heat source pendulum 7 moves in the same direction as the acceleration under the action of acceleration, the temperature field generated by the hot air flow is asymmetrically distributed. The temperature changes of two adjacent thermistors 8 and thermistor 10 or thermistor 9 and thermistor 11 in the same direction are opposite. The temperature of the thermistor deviated by the omnidirectional moving heat source pendulum is higher than that of the thermistor parallel to it, and a temperature difference is generated between two adjacent thermistors 8 and thermistor 10 or thermistor 9 and thermistor 11. In the figure, Tx1 corresponds to thermistor 9, Tx2 corresponds to thermistor 11, Ty1 corresponds to thermistor 8, and Ty2 corresponds to thermistor 10.

[0059] like Figure 6 As shown, thermistors 8 and 10 or thermistors 9 and 11 are used as two arms of a Wheatstone bridge. The temperature difference caused by the input line acceleration is converted into a change in the resistance of the bridge arm according to the thermal resistance effect, thereby causing an unbalanced bridge voltage V proportional to the input acceleration.X or V Y The linear acceleration of the x / y axis can be calculated based on the output voltage, so as to be sensitive to the acceleration in the X or Y direction, thus forming an omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer.

[0060] In this embodiment, as a further technical solution, the cover plate 5 and the base layer 1 isolate the gas medium of the intermediate heating chamber 4 and the intermediate detection chamber 3 from the outside to form a sealed working system; the height of the intermediate heating chamber 4 and the intermediate detection chamber 3 and the depth of the groove 6 in the upper sealing layer are the total cavity height z, 300μm≤z≤1000μm; the total cavity height in this embodiment is in the order of hundreds of microns, which can effectively suppress the natural convection movement of the gas flow in the cavity, thereby greatly reducing the influence of the Z-axis acceleration on the sensor performance. According to the requirements for the gyro performance, the total cavity height can be arbitrarily selected within the range of 300 microns to 1000 microns, for example, the total cavity height in the above embodiment can be 700 microns.

[0061] In this embodiment, as a further technical solution, increasing the depth of the groove of the cover plate can increase the space for gas flow, thereby increasing the sensitivity of the sensor. The depth of the groove 6 is 2 / 3 of the height of the cover plate 5 .

[0062] In this embodiment, as a further technical solution, the height of the heater and the thermistor on the upper surface of the sensitive layer is 100nm to 1000nm, so as to form a thin film resistor whose resistance value changes little with temperature and is more stable and reliable.

[0063] In this embodiment, as a further technical solution, the two pairs of thermistors have the same length, which is 1 / 6 to 1 / 5 of the width of the entire sensitive layer, in order to increase the stability and impact resistance of the sensor.

[0064] In this embodiment, as a further technical solution, the heater and the thermistor are both composed of a metal layer consisting of a chromium adhesion layer and a platinum layer.

[0065] Combination Figure 7 As shown, the manufacturing process of the omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer disclosed in the present invention is as follows:

[0066] Step (a): thermally oxidize a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer, such as Figure 7 (a) shown.

[0067] Step (b): Photolithography is performed on the silicon dioxide film to form a full-range dynamic heat source swing heater and a thermistor structure pattern, such as Figure 7 (b) as shown.

[0068] Step (c): sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and silicon dioxide in sequence by a magnetron sputtering process, such as Figure 7 (c) as shown.

[0069] Step (d): Use ultrasonic stripping process to strip off the metal layer outside the omnidirectional dynamic heat source swing heater and thermistor structure pattern, such as Figure 7 As shown in (d), an omnidirectional dynamic heat source swing heater and thermistor structure is formed.

[0070] Step (e): Use photolithography and wet etching process to etch away a portion of silicon dioxide, such as Figure 7 (e) as shown.

[0071] Step (f): A 300 μm deep groove is formed by etching with a silicon etching process, so that the omnidirectional dynamic heat source pendulum heater and thermistor are suspended and fixed on the sensitive layer through the silicon dioxide film, and the processing of the accelerometer sensitive layer is completed. Figure 7 (f) as shown.

[0072] Step (g): bonding the cover plate and the sensitive layer by a bonding process so that the upper surface of the sensitive layer is in a closed cavity to complete the processing of the accelerometer sensitive element and form an omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer.

[0073] In summary, the present invention breaks the inherent pattern of previous research on heat flow accelerometers and proposes an omnidirectional dynamic heat source pendulum type dual-axis micromechanical accelerometer, which moves a heater with a high temperature gradient, and allows it to be deflected by the inertial force to form a large temperature gradient at the thermistor, thereby achieving a high sensitivity output. This omnidirectional dynamic heat source pendulum heater is suspended at the center of the sensitive layer through six completely symmetrical semicircular support beams, which can realize the measurement of dual-axis acceleration, with high sensitivity and fast response speed. The hot wheel-like sensitive structure has high structural symmetry and low structural stress, which can ensure the consistency of azimuth detection. The structure can realize the production of relatively long elastic elements and relatively large mass blocks in a small area, thereby obtaining a large inertial force sensitivity. The sensitive element is made on a silicon chip through processes such as photolithography and corrosion, with good consistency, which is convenient for introducing a microcomputer embedded system (single-chip microcomputer) to perform temperature compensation and nonlinearity compensation, which can not only improve the performance of the sensor, but also realize mass production. This all-round dynamic heat source pendulum dual-axis micromechanical accelerometer not only inherits the advantages of MEMS heat flow accelerometer, but also has the characteristics of simple structure, small size, light weight, easy intelligence and integration, which is in line with the development direction of sensors towards miniature, comprehensive and intelligent. At the same time, it has the advantages of very simple structure and processing technology, extremely low cost, high reliability, excellent anti-vibration and shock characteristics, etc.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer, characterized in that: It includes a base layer, a sensitive layer and a cover plate, wherein: The sensitive layer comprises a middle heating cavity and a middle detection cavity, and an omnidirectional dynamic heat source pendulum heater and two pairs of thermistors are arranged on the upper surface of the sensitive layer; The length direction of the upper surface of the sensitive layer is defined as the X direction, the width is defined as the Y direction, and the height direction is defined as the Z direction; the two pairs of thermistors are placed in the X direction and the Y direction, and each pair of thermistors are parallel to each other, and are used to detect the acceleration of the X axis and the Y axis; The omnidirectional dynamic heat source pendulum heater adopts a Hot Wheels sensitive structure, the center of which contains a central wheel hub with a circular mass block, which is suspended at the center of the sensitive layer through six completely symmetrical semicircular support beams; below it is a circular intermediate heating cavity; in addition to being able to swing along the z-axis perpendicular to the sensitive layer, the omnidirectional dynamic heat source pendulum heater can also swing along any azimuth angle in the XOY plane where the sensitive layer is located; The two ends of the omnidirectional dynamic heat source pendulum heater cover symmetrical electrodes along the Y direction to form a movable resistive heat source; The thermistor includes a pair of thermistors for detecting X-axis acceleration and a pair of thermistors for detecting Y-axis acceleration, and a rectangular middle detection cavity is located below the thermistors; A pair of thermistors for detecting the acceleration of the X-axis are placed symmetrically along the Y-axis direction and perpendicular to the X-axis direction; a pair of thermistors for detecting the acceleration of the Y-axis are placed symmetrically along the X-axis direction and perpendicular to the Y-axis direction; The omnidirectional dynamic heat source pendulum heater and thermistor are powered by constant current; The cover plate is etched with a groove and is tightly connected to the upper surface of the sensitive layer; The cover plate and the base layer isolate the gas medium of the intermediate heating cavity and the intermediate detection cavity from the outside world to form a sealed working system; the height of the intermediate heating cavity and the intermediate detection cavity and the depth of the groove in the cover plate are the total cavity height z, 300μm≤z≤1000μm; The depth of the groove of the cover plate is 2 / 3 of the height of the cover plate.

2. The omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer according to claim 1, characterized in that: The height of the omnidirectional dynamic heat source pendulum heater and the thermistor is 100nm to 1000nm.

3. The omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer according to claim 1, characterized in that: The heater and the thermistor have the same length, both being 1 / 6 to 1 / 5 of the width of the entire sensitive layer.

4. The omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer according to claim 1, characterized in that: The heater and the thermistor are both composed of a metal layer consisting of a chromium adhesion layer and a platinum layer.

5. A method for processing the omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer according to any one of claims 1 to 4, characterized in that: The specific process is as follows: Step 1: thermally oxidize a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer; Step 2: Photolithography forms a full-range dynamic heat source swing heater and a thermistor structure pattern on the silicon dioxide film; Step 3: sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and silicon dioxide in sequence by using a magnetron sputtering process; Step 4: Use ultrasonic stripping process to strip off the metal layer outside the omnidirectional dynamic heat source pendulum heater and thermistor structure pattern to form the omnidirectional dynamic heat source pendulum heater and thermistor structure; Step 5: Use photolithography and wet etching process to etch away a portion of silicon dioxide; Step 6: Use silicon etching process to form a groove with a depth of 300 μm, so that the omnidirectional dynamic heat source pendulum heater and thermistor are suspended and fixed on the sensitive layer through the silicon dioxide film, and the processing of the accelerometer sensitive layer is completed; Step seven: The cover plate and the sensitive layer are bonded by a bonding process so that the upper surface of the sensitive layer is in a closed cavity to complete the processing of the accelerometer sensitive element and form an omnidirectional dynamic heat source pendulum dual-axis micromechanical accelerometer.

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