Dynamic heat source type omnidirectional micromechanical angular velocity sensor and its processing method

Abstract

The present invention discloses a dynamic heat source type omnidirectional micromechanical angular velocity sensor and a processing method thereof. The gyroscope includes a substrate layer, an upper sensitive layer, a lower sensitive layer and a cover plate; an omnidirectional vibrator heater (dynamic heat source) is arranged at the center of the upper sensitive layer, and is suspended at the center of the sensitive layer by eight completely symmetrical semicircular support beams, and a circular intermediate heating cavity is located below; the lower sensitive layer contains eight thermistors distributed in a regular octagon, and a rectangular intermediate detection cavity is located below; the upper sensitive layer and the lower sensitive layer are bonded to form a sensitive layer; the heater is powered by periodic alternating current; a groove is etched on the cover plate, and is sealed and connected to the upper surface of the sensitive layer. The present invention can realize omnidirectional measurement of angular velocity, is not limited by the azimuth angle, has a large range, a small measurement error, a high detection accuracy, and has the characteristics of compact structure, easy intelligence and integration. At the same time, it has extremely low cost, high reliability, and excellent anti-vibration and anti-impact performance.

Description

Technical Field

[0001] The invention belongs to the technical field of using Coriolis force to deflect an omnidirectional vibrator to detect angular velocity posture parameters of a moving body, in particular to a dynamic heat source type omnidirectional micromechanical angular velocity sensor and a processing method thereof, and belongs to the field of inertial measurement. Background Art

[0002] Micro inertial sensors made using 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. Gyroscopes and accelerometers are the core inertial sensors for measuring and controlling the motion attitude of carriers, and gyroscopes are sensors that are sensitive to angular parameters such as angular velocity and angular acceleration. At present, the market has higher and higher requirements for the ability of micro gyroscopes to adapt to harsh and demanding environments, and micro fluid inertial sensors (MEMS inertial sensors) are unique among MEMS sensors with their ultra-high impact resistance and ultra-low manufacturing cost, which is unmatched by other MEMS inertial sensors.

[0003] At present, microfluid gyroscopes based on MEMS technology can be roughly divided into four categories: micro jet gyroscopes, ECF (electro-conjugate fluid) fluid gyroscopes, micro thermal convection gyroscopes and micro thermal fluid gyroscopes. Chinese patent: A micro four-channel circulating flow three-axis silicon jet gyroscope (patent application number: 201510385582.4), which belongs to a micro jet gyroscope. The piezoelectric sheet in its sensitive element increases the difficulty and cost of processing, and its volume is difficult to further reduce while maintaining the flow rate. The volume of the ECF fluid gyroscope is large (40mm×60mm×7mm), and the liquid needs a voltage of up to thousands of volts to form a jet flow, so it is difficult for the ECF gyroscope to achieve large-scale, low-cost commercialization. The micro thermal convection gyroscope cannot work without a gravity field and has low sensitivity. The above-mentioned micro fluid gyroscopes are difficult to become the choice of low-cost commercial micro gyroscopes due to their inherent shortcomings. The micro thermal flow gyroscope (also called thermal expansion gyroscope) is a relatively new type of micro fluid gyroscope proposed in recent years. There is no piezoelectric plate in the sensitive element, high voltage is not required, and it can be used in a zero-gravity environment. Compared with the commercialized micro thermal flow accelerometer (MEMS thermal flow accelerometer), the MEMS thermal flow gyroscope is not yet mature and is still in the research and development stage. The difficulty in the practical application of MEMS thermal flow gyroscope is that the sensitivity is lower than that of the micromechanical vibration gyroscope. In Chinese patents 201410140298.6 and 201210130318.2, the micromechanical thermal flow gyroscope almost all uses a heater to generate a thermal expansion flow, which is deflected under the action of the Coriolis force when the angular velocity is input, and the asymmetric distribution of the temperature field is detected by setting a symmetrical thermistor. Since the thermal flow velocity is very small, the asymmetric temperature field gradient caused by the deflection of the airflow 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, due to the limitation of power consumption, there is no substantial change or improvement in the sensitivity, and it is difficult to break through this practical bottleneck. Summary of the invention

[0004] The object of the present invention is to provide a dynamic heat source type omnidirectional micromechanical angular velocity sensor and a processing method thereof, so as to solve the technical problems existing in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a dynamic heat source type omnidirectional micromechanical angular velocity sensor, comprising a base layer, an upper sensitive layer, a lower sensitive layer and a cover plate, wherein:

[0007] An omnidirectional vibrator heater is arranged at the center of the upper sensitive layer to form a dynamic heat source; the lower sensitive layer contains eight thermistors, which are located around the projection position of the omnidirectional vibrator heater and are distributed in a regular octagon; the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer;

[0008] 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 omnidirectional vibrator 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 eight completely symmetrical semicircular support beams; below it is a circular intermediate heating cavity;

[0009] The omnidirectional vibrator 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.

[0010] Both ends of the omnidirectional vibrator heater are covered with symmetrical electrodes along the X direction to form a movable resistive heat source;

[0011] Eight thermistors are parallel to each other and suspended on the surface of the lower sensitive layer. Below the thermistors is a rectangular middle detection cavity. The eight thermistors constitute two angular velocity detection units, and four thermistors distributed orthogonally and vertically in a cross shape constitute one of the angular velocity detection units. Each angular velocity detection unit can detect the angular velocity in two orthogonal vertical directions in the XOY plane.

[0012] The heater is powered by periodic alternating current, which generates an alternating excitation voltage; the thermistor is powered by constant current.

[0013] The cover plate is etched with a groove and is tightly connected to the upper surface of the upper sensitive layer;

[0014] 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;

[0015] As a further technical solution, the depth of the groove of the cover plate is 2 / 3 of the height of the cover plate.

[0016] As a further technical solution, the height of the heater and the thermistor is 100nm to 1000nm.

[0017] As a further technical solution, the length of the thermistor is 1 / 6 to 1 / 5 of the width of the entire sensitive layer.

[0018] 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.

[0019] A method for processing a dynamic heat source type omnidirectional micromechanical angular velocity sensor, the specific process flow is as follows:

[0020] Step 1: thermally oxidize a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer;

[0021] Step 2: Photolithography to form a thermistor structure pattern on the silicon dioxide film;

[0022] 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;

[0023] Step 4: Use ultrasonic peeling process to peel off the metal layer outside the thermistor structure pattern to form the thermistor structure;

[0024] Step 5: Use photolithography and wet etching process to etch away a portion of silicon dioxide;

[0025] Step 6: Use silicon etching process to form a groove with a depth of 300 μm, 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.

[0026] Step 7: thermally oxidize a 0.5 μm thick silicon dioxide film on another N-type (100) single crystal silicon wafer;

[0027] Step 8: Photolithography to form a omnidirectional oscillator heater structure pattern on the silicon dioxide film;

[0028] 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;

[0029] Step 10: Use an ultrasonic peeling process to peel off the metal layer outside the omnidirectional vibrator heater structure pattern to form an omnidirectional vibrator heater structure;

[0030] Step 11: Use photolithography and wet etching process to etch away a portion of silicon dioxide;

[0031] Step 12: Use silicon etching process to etch through and form a middle heating cavity, so that the omnidirectional vibrator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer of the gyroscope is completed;

[0032] Step 13: Bonding the lower sensitive layer and the upper sensitive layer through a bonding process;

[0033] 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 gyro sensitive element.

[0034] By adopting the above technical solution, the present invention has the following beneficial effects:

[0035] 1. This dynamic heat source omnidirectional micromechanical angular velocity sensor inherits the advantages of MEMS thermal flow gyroscope, with small size, light weight, and easy intelligence and integration.

[0036] 2. The sensitive structure of this gyroscope is the omnidirectional vibrator heater (dynamic heat source) in the middle. The omnidirectional vibrator is suspended in the center of the sensitive layer through eight completely symmetrical semicircular support beams. Its structure is more solid and reliable, which improves the impact resistance of the sensor. In addition to being able to vibrate along the Z axis perpendicular to the rotation plane, the omnidirectional vibrator has the degree of freedom of inertial force at any azimuth angle of the rotation plane. This sensitive structure can sense the input angular velocity of the rotation axis (sensitive axis) at any azimuth angle in the XOY plane, thereby realizing the omnidirectional measurement of the angular velocity in the XOY plane, which is not limited by the azimuth angle, has a wide measurement range, fast response speed, and strong impact resistance.

[0037] 3. This omnidirectional vibrator adopts a Hot Wheels sensitive structure, and the central wheel is a mass block and also a heater. This Hot Wheels 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 any azimuth detection; the Hot Wheels 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.

[0038] 4. When the angular velocity is input along the carrier at any azimuth angle, the output voltage of the angular velocity is averaged and output, and the detection sensitivity always maintains a constant value and does not change with different azimuth angles. At the same time, the quadrant and azimuth angle of the angular velocity can be accurately determined. Therefore, the sensor has a small measurement error and high detection accuracy.

[0039] 5. The sensitive element is made on a silicon wafer through photolithography, corrosion and other processes, with good consistency, which is convenient for introducing 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.

[0040] 6. It has a compact structure, extremely low cost, high reliability, and excellent anti-vibration and impact characteristics, making it possible to compete with capacitive micromechanical vibration gyroscopes in the medium, low-precision, and low-price micro-gyroscope market. 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 the three-dimensional structure of a sensor provided in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of a double-layer structure of a sensor 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 sensor provided by an embodiment of the present invention;

[0046] Figure 5 A top view of the lower sensitive layer of the sensor provided by an embodiment of the present invention;

[0047] Figure 6 for Figure 4 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 process flow chart of the preparation of a dynamic heat source omnidirectional micromechanical angular velocity sensor provided by an embodiment of the present invention;

[0051] Fig.10 A detection principle diagram of a dynamic heat source omnidirectional micromechanical angular velocity sensor provided by an embodiment of the present invention;

[0052] Icon: 1-base layer, 2-lower sensitive layer, 3-upper sensitive layer, 4-metal electrode, 5-middle heating cavity, 6-middle detection cavity, 7-cover plate, 8-groove, 9-omnidirectional vibrator heater, 10-thermistor, 11-thermistor, 12-thermistor, 13-thermistor, 14-thermistor, 15-thermistor, 16-thermistor, 17-thermistor. DETAILED DESCRIPTION

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] Combination Figure 1-6 As shown, this embodiment provides a dynamic heat source type omnidirectional micromechanical angular velocity sensor, including a substrate 1, an upper sensitive layer 3, a lower sensitive layer 2 and a cover plate 7, wherein:

[0058] An omnidirectional vibrator heater 9 is arranged at the center of the upper sensitive layer 3 to form a dynamic heat source; the lower sensitive layer 2 contains eight thermistors (thermistor 10, thermistor 11, thermistor 12, thermistor 13, thermistor 14, thermistor 15, thermistor 16, thermistor 17), which are located around the projection position of the omnidirectional vibrator heater 9 and are distributed in a regular octagon; the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer;

[0059] 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;

[0060] The omnidirectional vibrator heater 9 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 eight completely symmetrical semicircular support beams; below it is a circular intermediate heating chamber 5;

[0061] The omnidirectional vibrator heater 9 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.

[0062] Both ends of the omnidirectional vibrator heater 9 are covered with symmetrical metal electrodes 4 along the X direction to form a movable resistive heat source;

[0063] Thermistors 10, 11, 12, 13, 14, 15, 16 and 17 are parallel to each other and suspended on the surface of the lower sensitive layer, and a rectangular middle detection cavity 6 is located below the thermistors; the eight thermistors 10, 11, 12, 13, 14, 15, 16 and 17 constitute two angular velocity detection units;

[0064] The heater is powered by periodic alternating current, which generates an alternating excitation voltage; the thermistor is powered by constant current.

[0065] The cover plate 7 is etched with a groove 8 and is tightly connected to the upper surface of the upper sensitive layer 3 .

[0066] In this embodiment, as a further technical solution, the omnidirectional oscillator heater 9 has the degree of freedom of inertial force at any azimuth angle of the rotation plane, and can be sensitive to the input angular velocity of the rotation axis (sensitive axis) at any azimuth angle of the XOY plane, thereby realizing omnidirectional measurement of the angular velocity in the XOY plane without being restricted by the azimuth angle.

[0067] In this embodiment, as a further technical solution, the omnidirectional vibrator heater 9 is driven by an alternating excitation voltage to generate an alternating temperature field. The vibrator will generate alternating thermal stress along its axial direction and thickness direction. At the same time, the vibrator generates Joule heat when it is powered on, releases heat to the surrounding gas, performs heat diffusion, and forms a heat flow. When the frequency of the AC excitation signal is consistent with the vibration frequency of the vibrator along the thickness direction, the vibrator resonates in the thickness direction (Z-axis direction), generates displacement, and drives the heat flow to flow in the X-axis (Y-axis) direction.

[0068] In this embodiment, as a further technical solution, four thermistors 10, 11, 12 and 13 arranged orthogonally and vertically in a cross shape constitute an angular velocity detection unit, and four thermistors 14, 15, 16 and 17 arranged orthogonally and vertically in a cross shape constitute another angular velocity detection unit; each angular velocity detection unit can measure the angular velocity in two orthogonal vertical directions in the XOY plane.

[0069] Combination Figure 7 As shown, the angular velocity detection unit composed of thermistor 10, thermistor 11, thermistor 12, and thermistor 13 is taken as an example. When the angular velocity Ω is input along the direction of the connection line between thermistor 10 and thermistor 11 (X-axis direction), X When the omnidirectional vibrator heater 9 is deflected in the YOX plane in the direction of the connection line of thermistor 12 and thermistor 13 in the Y-axis direction (Y-axis direction) due to the Coriolis force principle, the temperature of the thermistor to which the hot vibrator is deflected is higher than the thermistor parallel to it, so the two relatively parallel thermistors 12 and 13 produce a temperature difference proportional to the input angular velocity ΩX. In the figure, T1-T8 correspond to thermistor 10, thermistor 11, thermistor 12, thermistor 13, thermistor 14, thermistor 15, thermistor 16, and thermistor 17, respectively.

[0070] like Figure 8 As shown, thermistor 12 and thermistor 13 are connected to form two equal arms of two Wheatstone bridges, and the input angular velocity Ω X The resulting temperature difference is converted into the angular velocity Ω by changing the resistance of the Wheatstone bridge arm. X Proportional to the voltage imbalance voltage V X The output is sensitive to the angular velocity in the X direction.

[0071] When the angular velocity Ω is input along the direction of the connection line between thermistor 12 and thermistor 13 (Y-axis direction) Y Due to the Coriolis force principle, the omnidirectional vibrator heater 9 will deflect in the YOX plane in the direction of the thermistor 10 and the thermistor 11 connecting the X-axis direction (X-axis direction). The temperature of the thermistor in the direction of the hot vibrator is higher than that of the thermistor parallel to it. Therefore, the two relatively parallel resistors, thermistor 10 and thermistor 11, generate the same angular velocity as the input Ω. Y is proportional to the temperature difference. Figure 8 As shown, thermistor 10 and thermistor 11 are connected to form two equal arms of two Wheatstone bridges, and the input angular velocity Ω Y The resulting temperature difference is converted into the angular velocity Ω by changing the resistance of the Wheatstone bridge arm.Y Proportional to the voltage imbalance voltage V Y Output, thereby sensitive to the angular velocity in the Y direction. Thermistor 10, thermistor 11, thermistor 12, thermistor 13 constitute an angular velocity detection unit, which can measure two mutually perpendicular angular velocities Ω X and Ω Y Similarly, another angular velocity detection unit composed of thermistor 14, thermistor 15, thermistor 16, and thermistor 17 can sensitively input the angular velocity Ω X1 and Ω Y1 ,Ω X1 The direction of is the connection direction of thermistor 14 and thermistor 15, Ω Y1 It is the connection direction of thermistor 16 and thermistor 17.

[0072] like Fig.10 As shown in the figure, when the plane where the sensor is located rotates around an arbitrary azimuth (azimuth angle is α), the coordinate axes change from X, Y, to X', Y', and the angular velocity Ω to be measured input along the azimuth angle α is projected on the coordinate axes X', Y' as Ω X ,Ω Y ,Ω X ,Ω Y The relationship with the angular velocity Ω to be measured is:

[0073]

[0074] By measuring Ω X ,Ω Y You can know the angular velocity Ω along any azimuth input. Here Ω X ,Ω Y The angular velocity detection unit can be used to measure the angular velocity. X ,Ω Y According to formula (1), the angular velocity along any azimuth input is calculated and represented by Ω1. The Ω output by the second angular velocity detection unit is X1 and Ω Y1 , the angular velocity along any azimuth input is calculated according to formula (1), represented by Ω2. The average value of Ω1 and Ω2 is used to obtain the value of Ω:

[0075]

[0076] That is, a dynamic heat source type omnidirectional micromechanical angular velocity sensor is formed. This detection method can largely avoid errors caused by process reasons and improve detection accuracy. The direction of the angular velocity can be determined by the change in the resistance of the eight thermistors, and the quadrant and azimuth angle.

[0077] In this embodiment, as a further technical solution, the cover plate 7 and the base layer 1 isolate the gas medium of the intermediate heating cavity 5 and the intermediate detection cavity 6 from the outside world to form a sealed working system; the height of the intermediate heating cavity 5 and the intermediate detection cavity 6 and the depth of the groove 8 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.

[0078] 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 8 is 2 / 3 of the height of the cover plate 7.

[0079] In this embodiment, as a further technical solution, in order to form a thin film resistor whose resistance value changes less with temperature and is more stable and reliable, the height of the heater and thermistor on the upper surface of the sensitive layer is 100nm to 1000nm.

[0080] In this embodiment, as a further technical solution, in order to increase the stability and impact resistance of the sensor, the length of the thermistor is 1 / 6 to 1 / 5 of the width of the entire sensitive layer.

[0081] 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.

[0082] Combination Fig. 9 As shown, the dynamic heat source type omnidirectional micromechanical angular velocity sensor disclosed in the present invention has the following manufacturing process:

[0083] Step (a): thermally oxidize a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer, such as Fig. 9 (a) shown.

[0084] Step (b): Photolithography is performed on the silicon dioxide film to form a thermistor structure pattern, such as Fig. 9 (b) as shown.

[0085] 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 Fig. 9 (c) as shown.

[0086] Step (d): Use ultrasonic stripping process to strip off the metal layer outside the thermistor structure pattern, such as Fig. 9As shown in (d), a thermistor structure is formed.

[0087] Step (e): Use photolithography and wet etching process to etch away a portion of silicon dioxide, such as Fig. 9 (e) as shown.

[0088] Step (f): A 300 μm deep groove is formed by etching with a silicon etching process, 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. Fig. 9 (f) as shown.

[0089] Step (g): thermally oxidize a 0.5 μm thick silicon dioxide film on another N-type (100) single crystal silicon wafer, such as Fig. 9 (g) as shown.

[0090] Step (h): Photolithography is performed on the silicon dioxide film to form an omnidirectional oscillator heater structure, such as Fig. 9 (h) shown.

[0091] 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, such as Fig. 9 (i) as shown.

[0092] Step (j): Use ultrasonic stripping process to strip off the metal layer outside the structure pattern of the omnidirectional vibrator heater, such as Fig. 9 As shown in (j), an omnidirectional vibrator heater structure is formed.

[0093] Step (k): Use photolithography and wet etching process to etch away a portion of silicon dioxide, such as Fig. 9 (k) as shown.

[0094] Step (1): using silicon etching technology to etch and carve through to form a middle heating cavity, so that the omnidirectional vibrator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer of the gyroscope is completed. Fig. 9 (l) as shown.

[0095] Step (m): Bonding the lower sensitive layer and the upper sensitive layer by a bonding process, such as Fig. 9 (m) shown.

[0096] 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 gyro sensitive element.

[0097] In summary, the present invention breaks the inherent pattern of previous research on thermal flow gyroscopes, and proposes a dynamic heat source type omnidirectional micromechanical angular velocity sensor, 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 vibrator heater (dynamic heat source) is suspended at the center of the sensitive layer through eight completely symmetrical semicircular support beams, which can realize the measurement of angular velocity in all directions, is not limited by the azimuth angle, has a wide measurement range, fast response speed, and strong impact resistance. The hot wheel type sensitive structure has high structural symmetry and low structural stress, which can ensure the consistency of detection at any azimuth angle. When the angular velocity is input along the carrier around any azimuth angle, the output voltage of the angular velocity is averaged and output, and the detection sensitivity always maintains a constant value, which will not change due to different azimuth angles, and the quadrant and azimuth angle of the angular velocity can be accurately determined. Therefore, the measurement error is small and the detection accuracy is high. 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 wafer through photolithography, corrosion and other processes, with good consistency, which is convenient for introducing microcomputer embedded systems (single-chip microcomputers) to perform temperature compensation and nonlinearity compensation, which can not only improve the performance of the sensor, but also realize mass production. This dynamic heat source type all-round micro-mechanical angular velocity sensor not only inherits the advantages of MEMS thermal flow gyroscopes, 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 a very simple structure and processing technology, extremely low cost, high reliability, and excellent anti-vibration and impact characteristics, making it possible for it to compete with capacitive micro-mechanical vibration gyroscopes in the medium, low-precision, low-price micro-gyroscope market.

[0098] 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. A dynamic heat source type omnidirectional micromechanical angular velocity sensor, characterized in that: It includes a base layer, an upper sensitive layer, a lower sensitive layer and a cover plate, wherein: An omnidirectional vibrator heater is arranged at the center of the upper sensitive layer to form a dynamic heat source; the lower sensitive layer contains eight thermistors, which are located around the projection position of the omnidirectional vibrator heater and are distributed in a regular octagon; the upper sensitive layer and the lower sensitive layer are bonded together to form a 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 omnidirectional vibrator 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 eight completely symmetrical semicircular support beams; below it is a circular intermediate heating cavity; The omnidirectional vibrator 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; Both ends of the omnidirectional vibrator heater are covered with symmetrical electrodes along the X direction to form a movable resistive heat source; The eight thermistors are parallel to each other and suspended on the surface of the lower sensitive layer, and below the thermistors is a rectangular middle detection cavity; the eight thermistors constitute two angular velocity detection units, four thermistors orthogonally distributed in a cross shape constitute one of the angular velocity detection units, and each angular velocity detection unit can detect the angular velocity in two orthogonal vertical directions in the XOY plane; The heater is powered by periodic alternating current, which generates an alternating excitation voltage; the thermistor is powered by constant current. The cover plate is etched with a groove and is tightly connected to the upper surface of the upper 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 dynamic heat source type omnidirectional micromechanical angular velocity sensor according to claim 1, characterized in that: The heater and the thermistor have a height of 100 nm to 1000 nm.

3. The dynamic heat source type omnidirectional micromechanical angular velocity sensor according to claim 1, characterized in that: The length of the thermistor is consistent, being 1 / 6 to 1 / 5 of the width of the entire lower sensitive layer.

4. The dynamic heat source type omnidirectional micromechanical angular velocity sensor 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 dynamic heat source type omnidirectional micromechanical angular velocity sensor according to any one of claims 1 to 4, 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 peeling process to peel 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 technology to etch through and form a middle heating cavity, so that the omnidirectional vibrator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer of the gyroscope 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 gyro sensitive element.

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