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

Abstract

The present invention discloses an all-round dynamic heat source Z-axis micromechanical accelerometer and a processing method thereof, wherein the Z-axis micromechanical accelerometer comprises an upper sensitive layer, a lower sensitive layer, a base layer and a cover plate; a heater is arranged at the center of the upper sensitive layer, and a middle heating cavity is arranged below; the lower sensitive layer comprises two thermistors, and a rectangular middle detection cavity is arranged below; the heater and the thermistor are both powered by constant current; the heater is suspended at the center of the upper sensitive layer by three semicircular support beams; a groove is etched on the cover plate, and is tightly connected to the surface of the upper sensitive layer. The sensitive element adopted by the present invention is made on a silicon wafer by processes such as photolithography and corrosion, which can not only improve the performance of the sensor, but also realize mass production. The present invention can realize the measurement of Z-axis acceleration, and has the characteristics of high sensitivity, fast measurement speed, and compact structure.

Description

Technical Field

[0001] The present invention relates to a technology for detecting acceleration attitude parameters of a moving carrier by swinging a omnidirectional dynamic heat source pendulum under the action of linear acceleration, and in particular to an omnidirectional dynamic heat source Z-axis micromechanical accelerometer and a processing method thereof, and belongs 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 sensors.

[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 up 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 it 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. China Patent: The micro-mechanical heat flow accelerometer in the micro-silicon bridge thermal convection accelerometer (patent application number 02116842.3) uses 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 object of the present invention is to provide an omnidirectional dynamic heat source type Z-axis micromechanical accelerometer and a processing method thereof, so as 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 Z-axis micromechanical accelerometer, comprising an upper sensitive layer, a lower sensitive layer, a base layer and a cover plate, wherein:

[0008] A heater is arranged at the center of the upper sensitive layer, two thermistors are arranged on the upper surface of the lower sensitive layer, and the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer;

[0009] The length and width directions of the rectangular sensitive layer are defined as the X and Y directions respectively, and the height direction of the sensitive layer is defined as the Z direction; the placement direction of the thermistor is perpendicular to the X direction; the two thermistors are arranged opposite to each other to detect the acceleration of the Z axis;

[0010] The heater is suspended at the center of the upper sensitive layer by three semicircular spokes (also called support beams) evenly arranged at equal intervals to form a heater; two thermistors are symmetrically arranged in the Y direction on the lower sensitive layer, respectively on the left and right sides of the heater;

[0011] In addition to being able to swing along the Z axis perpendicular to the sensitive layer, the heater can also swing along any azimuth angle in the XOY plane where the sensitive layer is located;

[0012] Both ends of the heater are covered with symmetrical electrodes along the Y direction to form a movable resistive heat source;

[0013] Below the thermistor is a rectangular middle detection cavity having the same depth as the middle heating cavity;

[0014] The heater and thermistor are powered by constant current.

[0015] 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.

[0016] As a further technical solution, the depth of the groove of the cover plate is 2 / 3 of the height of the cover plate.

[0017] As a further technical solution, the height of the heater and the thermistor on the upper surface of the sensitive layer is 100 nm to 1000 nm.

[0018] As a further technical solution, the two thermistors have the same length, which is 1 / 6 to 1 / 5 of the width of the entire sensitive layer.

[0019] As a further technical solution, the heater is composed of a metal layer consisting of a chromium adhesion layer and a platinum layer.

[0020] A method for machining an omnidirectional dynamic heat source pendulum Z-axis micromechanical accelerometer, the specific process flow is as follows:

[0021] Step 1: Thermally oxidize a 0.5µm thick silicon dioxide film on an N-type (100) single crystal silicon wafer;

[0022] Step 2: Photolithography to form a thermistor structure pattern on the silicon dioxide film;

[0023] 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;

[0024] Step 4: Use ultrasonic stripping process to strip off the metal layer outside the thermistor structure pattern to form the thermistor structure;

[0025] Step 5: Use photolithography and wet etching process to etch away a portion of silicon dioxide;

[0026] Step 6: Use silicon etching process to form a groove with a depth of 300µm, so that the thermistor is suspended and fixed on the lower sensitive layer through the silicon dioxide film, and the processing of the lower sensitive layer is completed;

[0027] Step 7: Thermally oxidize a 0.5µm thick silicon dioxide film on another N-type (100) single crystal silicon wafer;

[0028] Step 8: Photolithography to form a omnidirectional oscillator heater structure pattern on the silicon dioxide film;

[0029] Step nine: 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;

[0030] Step 10: Use an ultrasonic stripping process to strip off the metal layer outside the omnidirectional vibrator heater structure pattern to form an omnidirectional vibrator heater structure;

[0031] Step 11: Use photolithography and wet etching process to etch away a portion of silicon dioxide;

[0032] Step 12: Use silicon etching process to etch through and form a middle heating cavity, so that the omnidirectional oscillator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer is completed;

[0033] Step 13: Bonding the lower sensitive layer and the upper sensitive layer by a bonding process;

[0034] Step 14: Bond the cover plate and the upper sensitive layer through a bonding process so that the upper surface of the sensitive layer is in a closed cavity, completing the processing of the sensitive element.

[0035] By adopting the above technical solution, the present invention has the following beneficial effects:

[0036] 1. This dynamic heat source Z-axis micromechanical accelerometer inherits the advantages of MEMS heat flow accelerometer, with compact structure, small size, light weight, and easy intelligence and integration.

[0037] 2. The sensitive structure of this accelerometer is the heater in the middle. This omnidirectional dynamic heat source pendulum is suspended at the center of the sensitive layer through three completely symmetrical semicircular support beams. The characteristics of this dynamic heat source pendulum are flexible movement, large swing amplitude, and small input acceleration can obtain large inertial force sensitivity. In addition to being able to swing up and down along the Z axis perpendicular to the plane of the sensitive layer, the omnidirectional dynamic heat source pendulum has the freedom (swing) of inertial force at any azimuth angle on the XOY plane of the sensitive layer. This sensitive structure can sense the input acceleration along the Z axis, thereby realizing the measurement of Z-axis acceleration, with high sensitivity and fast response speed.

[0038] 3. This heater adopts a hot wheel type sensitive structure and a sensitive structure center support with small structural stress.

[0039] 4. Good consistency, easy to introduce into microcomputer embedded system (single chip microcomputer), perform temperature compensation and nonlinearity compensation, and realize mass production.

[0040] 5. It has compact structure, extremely low cost, high reliability, and excellent anti-vibration and shock properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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.

[0042] Figure 1 A schematic diagram of a three-dimensional structure of an accelerometer provided in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of a three-dimensional double-layer structure of a sensitive layer provided in an embodiment of the present invention;

[0044] Figure 3 A schematic diagram of a three-dimensional structure of a cover plate provided in an embodiment of the present invention;

[0045] Figure 4 A top view of a lower sensitive layer provided by an embodiment of the present invention;

[0046] Figure 5 A top view of an accelerometer provided by an embodiment of the present invention;

[0047] Figure 6 for Figure 5 AA section view;

[0048] Figure 7 A working principle diagram provided for an embodiment of the present invention;

[0049] Figure 8 A schematic diagram of an output circuit provided by an embodiment of the present invention;

[0050] Fig. 9 A flow chart of the manufacturing process of the omnidirectional dynamic heat source pendulum Z-axis micromechanical accelerometer provided by an embodiment of the present invention;

[0051] Icon: 1-base layer, 2-lower sensitive layer, 3-upper sensitive layer, 4-middle heating cavity, 5-heater, 6-electrode, 7-middle detection cavity, 8-thermistor, 9-thermistor, 10-cover plate, 11-rectangular groove. DETAILED DESCRIPTION

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Combination Figure 1-6 As shown, this embodiment provides an omnidirectional dynamic heat source Z-axis micromechanical accelerometer, including a base layer 1, a lower sensitive layer 2, an upper sensitive layer 3 and a cover plate 10, wherein:

[0057] A heater 5 is provided at the center of the upper sensitive layer 3, and two thermistors are provided at the lower sensitive layer 2. The upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer.

[0058] The length and width directions of the rectangular accelerometer are defined as the X and Y directions respectively, and the height direction of the sensitive layer is defined as the Z direction; the placement direction of the thermistor is perpendicular to the X direction and parallel to the Y direction; the two thermistors are arranged opposite to each other and are used to detect the acceleration of the Z axis;

[0059] The heater 5 is suspended at the center of the upper sensitive layer 3 by three semicircular spokes (also called support beams) evenly arranged at equal intervals, and below it is the middle heating chamber 4;

[0060] The heater 5 is arranged perpendicular to the Z axis at the center of the upper sensitive layer 3; the thermistors 8 and 9 are symmetrically arranged on the lower sensitive layer 2, respectively on the left and right sides of the heater 5;

[0061] In addition to being able to swing along the Z axis perpendicular to the sensitive layer, the heater 5 can also swing along any azimuth angle in the XOY plane where the sensitive layer is located;

[0062] The heater 5 and the thermistor are both powered by constant current;

[0063] A rectangular groove 11 is etched on the cover plate 10 and is tightly connected to the upper sensitive layer 3 .

[0064] Both ends of the heater are covered with symmetrical electrodes 6 along the Y direction to form a movable resistive heat source.

[0065] Combination Figure 7 and Figure 8 As shown in this embodiment, as a further technical solution, a constant current is passed through the heater 5, and the resistance heater generates Joule heat when it is energized, releases heat to the surrounding gas, performs heat diffusion, and forms a heat flow around it. The temperature field generated by the heat flow is generated by two thermistors T with the same resistance value. z1 (thermistor 8), T z2 (Thermistor 9) is symmetrically distributed. When there is a linear acceleration input perpendicular to the direction of the sensitive layer in the Z-axis direction, the omnidirectional dynamic heat source moves in the same direction as the acceleration under the action of the acceleration. When the acceleration is directed toward the thermistor input along the Z-axis, the omnidirectional dynamic heat source approaches the two thermistors, and the resistance of the two thermistors increases. The voltage across the two thermistors and V z Similarly, when the acceleration is input along the thermistor opposite to the Z axis, the heater moves away from the two thermistors, the resistance of the two thermistors decreases, and the voltage across the two thermistors and V z Therefore, V z The magnitude of the acceleration is detected by V z The direction of the acceleration is detected by increasing or decreasing the change, thereby being sensitive to the acceleration in the Z-axis direction, thus forming an omnidirectional dynamic heat source pendulum Z-axis micromechanical accelerometer.

[0066] The cover plate 10 and the base layer 1 isolate the gas medium of the intermediate heating chamber 4 and the intermediate detection chamber 7 from the outside world to form a sealed working system; the height of the intermediate heating chamber 4 and the intermediate detection chamber 7 and the depth of the groove 11 in the upper sealing layer are the total cavity height z, 300μm≤z≤1000μm.

[0067] In this embodiment, as a further technical solution, the depth of the groove 11 is 2 / 3 of the height of the cover plate 10, so that the total cavity height is on the order of hundreds of microns.

[0068] In this embodiment, as a further technical solution, the height of the heater and thermistor on the upper surface of the sensitive layer is 100nm to 1000nm, and the total cavity height is on the order of hundreds of microns, which can effectively suppress the natural convection movement of the gas flow in the cavity, thereby reducing the impact on the sensor performance.

[0069] In this embodiment, as a further technical solution, the thermistor 8 and the thermistor 9 have the same length, both of which are 1 / 6 to 1 / 5 of the width of the entire sensitive layer, which can improve the sensitivity of the sensor.

[0070] Combination Fig. 9 As shown, the specific process flow of the omnidirectional dynamic heat source Z-axis micromechanical accelerometer disclosed in the present invention is as follows:

[0071] Step (a): Thermally oxidize a 0.5µm thick silicon dioxide film on an N-type (100) single crystal silicon wafer.

[0072] Step (b): Photolithography is performed on the silicon dioxide film to form a full-range oscillator heater and a thermistor structure pattern.

[0073] 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 using a magnetron sputtering process.

[0074] Step (d): using an ultrasonic stripping process to strip off the metal layer outside the omnidirectional vibrator heater and thermistor structure pattern to form an omnidirectional vibrator heater and thermistor structure.

[0075] Step (e): using photolithography and wet etching processes to etch away a portion of the silicon dioxide.

[0076] Step (f): A silicon etching process is used to form a groove with a depth of 300 µm, so that the omnidirectional oscillator heater and thermistor are suspended and fixed on the sensitive layer through the silicon dioxide film, thereby completing the processing of the sensitive layer.

[0077] Step (g): thermally oxidize a 0.5µm thick silicon dioxide film on another N-type (100) single crystal silicon wafer.

[0078] Step (h): Photolithography is performed on the silicon dioxide film to form an omni-directional oscillator heater structure.

[0079] Step (i): 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.

[0080] Step (j): using an ultrasonic stripping process to strip off the metal layer outside the omnidirectional vibrator heater structure pattern to form an omnidirectional vibrator heater structure.

[0081] Step (k): using photolithography and wet etching processes to etch away a portion of the silicon dioxide.

[0082] Step (1): using a silicon etching process to etch through and form an intermediate heating cavity, so that the omnidirectional oscillator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, thereby completing the processing of the upper sensitive layer.

[0083] Step (m): bonding the lower sensitive layer and the upper sensitive layer by a bonding process.

[0084] Step (n): The cover plate and the upper sensitive layer are bonded together by a bonding process so that the upper surface of the sensitive layer is in a closed cavity, thereby completing the processing of the sensitive element.

[0085] In summary, the present invention breaks the inherent pattern of previous research on heat flow accelerometers, and proposes an all-round dynamic heat source Z-axis micromechanical accelerometer, which moves a heater with a high temperature gradient, deflects it under the action of inertial force, forms a large temperature gradient at the thermistor, and thus realizes a high-sensitivity output. This heater is suspended at the center of the sensitive layer through three completely symmetrical semicircular support beams, and has flexible movement and large swing amplitude, and can realize the measurement of Z-axis acceleration, high sensitivity, and fast response speed. The hot wheel-like sensitive structure has high structural symmetry and low structural stress. This 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 wafer through processes such as photolithography and corrosion, with good consistency, and is easy to introduce into 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. This all-round dynamic heat source pendulum Z-axis micromechanical accelerometer not only inherits the advantages of MEMS heat flow accelerometer, but also has the characteristics of compact 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.

[0086] 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 Z-axis micromechanical accelerometer, characterized in that: It includes an upper sensitive layer, a lower sensitive layer, a base layer and a cover plate, wherein: The upper sensitive layer is provided with a heater on its surface and contains a middle heating cavity below; the lower sensitive layer is provided with a pair of thermistors and contains a middle detection cavity below; the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer; The length and width directions of the rectangular accelerometer are defined as the X and Y directions respectively, and the height direction of the sensitive layer is defined as the Z direction; the placement directions of the thermistors are perpendicular to the X direction; the two thermistors are arranged opposite to each other to detect the acceleration of the Z axis; The heater is suspended at the center of the upper sensitive layer by three semicircular spokes evenly spaced at equal intervals to form a heater; two thermistors are located in the lower sensitive layer and are symmetrically arranged on the left and right sides of the heater along the Y direction; In addition to being able to swing along the Z axis perpendicular to the sensitive layer, the heater can also swing along any azimuth angle in the XOY plane where the sensitive layer is located; Both ends of the heater are covered with symmetrical electrodes along the Y direction to form a movable resistive heat source; Below the thermistor is a rectangular middle detection cavity having the same depth as the middle heating cavity; The heater and thermistor are powered by constant current. The cover plate and the base 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 upper sealing layer 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; The total height of the heater and thermistor of the sensitive layer is 100 nm to 1000 nm.

2. The omnidirectional dynamic heat source Z-axis micromechanical accelerometer according to claim 1, characterized in that: The lengths of the two thermistors are consistent, both being 1 / 6 to 1 / 5 of the width of the entire lower sensitive layer.

3. The omnidirectional dynamic heat source Z-axis micromechanical accelerometer according to claim 1, characterized in that: The heater is composed of a metal layer consisting of a chromium adhesion layer and a platinum layer.

4. A method for processing the omnidirectional dynamic heat source Z-axis micromechanical accelerometer according to any one of claims 1 to 3, characterized in that: The specific process is as follows: Step 1: Thermally oxidize a 0.5µm thick silicon dioxide film on an N-type (100) single crystal silicon wafer; Step 2: Photolithography to form 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 thermistor structure pattern to form the 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 300µm, so that the thermistor is suspended and fixed on the lower sensitive layer through the silicon dioxide film, and the processing of the lower sensitive layer is completed; Step 7: Thermally oxidize a 0.5µm thick silicon dioxide film on another N-type (100) single crystal silicon wafer; Step 8: Photolithography to form a omnidirectional oscillator heater structure pattern on the silicon dioxide film; Step nine: 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 10: Use an ultrasonic stripping process to strip off the metal layer outside the omnidirectional vibrator heater structure pattern to form an omnidirectional vibrator heater structure; Step 11: Use photolithography and wet etching process to etch away a portion of silicon dioxide; Step 12: Use silicon etching process to etch through and form a middle heating cavity, so that the omnidirectional oscillator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer is completed; Step 13: Bonding the lower sensitive layer and the upper sensitive layer by a bonding process; Step 14: Bond the cover plate and the upper sensitive layer through a bonding process so that the upper surface of the sensitive layer is in a closed cavity, completing the processing of the sensitive element.

Images