CN212082386U

CN212082386U - Cross-shaped push-pull flow micro-mechanical three-axis film gyroscope

Info

Publication number: CN212082386U
Application number: CN202021188150.7U
Authority: CN
Inventors: 李备; 朴林华; 朴然; 李美樱; 王灯山
Original assignee: Beijing Information Science and Technology University
Current assignee: Beijing Information Science and Technology University
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2020-12-04
Anticipated expiration: 2030-06-24

Abstract

The utility model discloses a cross-shaped push-pull flow micromechanical triaxial film gyroscope, which comprises a sensitive layer and a cover plate, wherein the upper surface of the sensitive layer is provided with four pairs of heaters and six pairs of thermistors which are in a cross-shaped structure, and the lower surface of the sensitive layer is etched with a cross-shaped groove; the pair of heaters, the pair of thermistors and the thermistor in the X/Y direction form a measuring unit; the energization mode of the four pairs of heaters is periodic push-pull energization; the cover plate is etched with a groove and is hermetically connected with the upper surface of the sensitive layer. The utility model provides a MEMS top based on thermal energy flows forms the hot flow of the push-pull of "ten" style of calligraphy distribution, and this kind of push-pull hot flow velocity of flow is big, the air current state is stable, and top sensitivity is high, and stability is good, can realize the simultaneous measurement of space triaxial angular velocity, has very high integrated level.

Description

Cross-shaped push-pull flow micro-mechanical three-axis film gyroscope

Technical Field

The utility model belongs to the technical field of the technique that utilizes the sensitive physical detection of brother's power deflection heat current to detect motion body angular velocity gesture parameter and specifically relates to a "ten" style of calligraphy push-pull flows micromechanical triaxial film top.

Background

The Micro inertial sensor manufactured by using Micro-Electro-Mechanical-System (MEMS) technology has the advantages of mass production, low cost, small volume, low power consumption and the like, and is an ideal product of the future medium and low precision Micro inertial sensors. The gyroscope and the accelerometer are core inertial sensors for measuring and controlling the motion attitude of the carrier, and the gyroscope is a sensor sensitive to angular velocity, angular acceleration and other angular parameters. The traditional micro gyroscope (micromechanical gyroscope) is a micro rate gyroscope based on the principle of the Coriolis effect existing when a high-frequency vibrating mass is driven to rotate by a base, and micro-electronics and a micro machine are combined. The solid mass block in the gyro sensitive element needs to be suspended and vibrated through a mechanical elastic body, is easy to damage under slightly high acceleration impact, and simultaneously needs vacuum packaging for reducing damping, has complex process and can generate fatigue damage and vibration noise when working for a long time. The micro fluid inertia device is a novel device for measuring input acceleration and angular velocity by detecting the flow field offset of fluid in a closed cavity. Because the movable part and the suspension system in the traditional miniature gyro are not provided, the high overload can be resisted; the sensitive mass of the gas sensor is gas, and the mass is almost zero, so the response time is short and the service life is long; due to the simple structure, the application requirement of low cost can be met. The micro fluid gyroscope is an angular velocity sensor which utilizes the deflection of an air flow sensitive body in a closed cavity under the action of Goldson force and senses the deflection quantity caused by angular velocity by a thermistor (hot wire). At present, the market has higher and higher requirements on the capability of the micro inertial gyroscope to adapt to severe and harsh environments, and compared with the traditional micro mechanical vibration gyroscope, the micro fluid gyroscope has higher market competitiveness and very wide application prospect due to the advantages of extremely high vibration resistance and impact resistance, low cost and the like.

The micro fluid gyroscopes based on MEMS technology can be broadly classified into four types, namely micro fluidic gyroscopes, ECF (electro-coupled fluid) fluid gyroscopes, micro thermal convection gyroscopes and micro thermal flow gyroscopes. Chinese patent: a miniature four-channel circulating flow type three-axis silicon jet gyro (patent application number: 201510385582.4) belongs to a miniature jet gyro, a piezoelectric plate in a sensitive element of the miniature jet gyro increases processing difficulty and cost, and the volume of the miniature jet gyro is difficult to further reduce on the premise of keeping flow rate. ECF fluid gyroscopes are relatively large (40mm x 60mm x 7mm) and are difficult to commercialize in large volumes and at low cost because of the high kilovoltage required to form the liquid jet. The miniature thermal convection gyro cannot work without a gravity field, and the sensitivity is low. The above-described microfluidic gyros have their own inherent disadvantages that make them difficult to be the low-cost choice for commercial microfluidic gyros. The miniature heat flow gyro (also called thermal expansion gyro) is a new miniature fluid gyro which is proposed in recent years, the sensing element has no piezoelectric plate, does not need high voltage, can be used in the environment without gravity, and has moderate sensitivity, is between the miniature heat flow gyro and the miniature heat convection gyro, and simultaneously has the advantages of simple structure and processing technology, extremely low cost, high reliability and excellent vibration and impact resistance.

The sensitive working principle of the micro heat flow gyroscope is that a heater is electrified to generate joule heat to heat gas around the heater to form gas heat diffusion and generate an air flow sensitive body moving along a certain direction, and when an angular velocity is input, the air flow sensitive body deflects under the action of a Coriolis force to change a bridge arm resistor (generally composed of thermistors) of a Wheatstone bridge, so that bridge unbalanced voltage in direct proportion to the input angular velocity is output. In chinese patents 201410140298.6 and 201210130318.2, the main components in the sensor sensing element, i.e., the heater and the thermistor, both adopt a suspended cantilever beam structure, and since the heater and the thermistor are suspended above the cavity, after the cavity release structure is etched, the heater and the thermistor may be deformed or even broken by stress, the yield is low, and the warp deformation may generate an asymmetric gas flow field under the condition of no angular velocity input, thereby causing an angular velocity detection error. Therefore, how to overcome the above problems becomes a technical problem to be solved urgently by those skilled in the art.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information constitutes prior art already known to a person skilled in the art.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a "ten" style of calligraphy push-pull flows micromechanical triaxial film top to solve the technical problem who exists among the prior art.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the utility model provides a cross-shaped push-pull flow micro mechanical three-axis film gyroscope, which comprises a sensitive layer and a cover plate, wherein,

four pairs of heaters and six pairs of thermistors which are in a cross-shaped structure are arranged on the upper surface of the sensitive layer, and a cross-shaped groove is etched on the lower surface of the sensitive layer;

defining the directions of two arms of the cross-shaped groove as an X direction and a Y direction respectively, and defining the height direction of the sensitive layer as a Z direction; the arrangement directions of the heater and the thermistor are parallel or vertical to the X or Y direction; four pairs of heaters and six pairs of thermistors form a cross network, and the cross network is symmetrically arranged along two vertical coordinate axes of X, Y; the pair of heaters, the pair of thermistors and the thermistors in the X/Y direction form a measuring unit, and the measuring unit is formed by the pair of heaters, the pair of thermistors and the thermistors in the X/Y direction;

two thermistors for detecting the angular speed of the X axis are symmetrically arranged along the X axis direction of the cross-shaped structure and are vertical to the Y axis direction; two thermistors for detecting the angular speed of the Y axis are symmetrically arranged along the Y axis direction of the cross-shaped structure and are vertical to the X axis direction; eight thermistors for detecting the angular speed of the Z axis are arranged on each measuring unit in the X/Y direction of the cross-shaped structure and are vertical to the direction of the heater;

two pairs of the four pairs of heaters are arranged in the X-axis direction and are vertical to the X-axis; the other two pairs are arranged in the Y-axis direction and are vertical to the Y-axis;

the four pairs of heaters are powered on in a periodic push-pull mode, namely one working period of the heaters comprises pulse voltage excitation time and power-off interval time;

and the cover plate is etched with a groove and is hermetically connected with the upper surface of the sensitive layer.

As a further technical scheme, each pair of heaters is driven by two square wave signals with the same frequency, the phase difference is 90 degrees, and the pulse duty ratio is 50%.

As a further technical scheme, the outer edge of the cross-shaped groove is larger than the outer contours of the upper surface heater and the thermistor.

As a further technical scheme, the height of the cross-shaped groove is 2/3-3/4 of the height of the whole sensitive layer.

As a further technical scheme, the depth of the groove etched on the cover plate is 50-100 μm.

As a further technical scheme, the height of the heater and the thermistor on the upper surface of the sensitive layer is 15-20 μm.

As a further technical scheme, the width of the measuring unit is 1/6-1/5 of the width of the whole sensitive layer.

As a further technical scheme, the heater is composed of a TaN material resistance wire with high temperature coefficient.

As a further technical scheme, the thermistor is formed by heavily doped n-type GaAs material resistance wires.

Adopt above-mentioned technical scheme, the utility model discloses following beneficial effect has:

the utility model provides a "ten" style of calligraphy push-pull flows micromechanical triaxial film top adopts the sensitive layer that has "ten" style of calligraphy heater and thermistor to cooperate corresponding signal detection processing circuit, can realize measuring when space triaxial angular velocity, inherited miniature thermal current top and do not have solid sensitive mass piece, advantages such as anti-vibration and impact have realized the multi freedom measurement based on the MEMS top of thermal expansion stream. Compare the miniature efflux top that proposes in application number 201510385582.4's the patent, the utility model provides a do not have the cantilever beam structure among the sensing element of top, have anti big impact, simple structure, the cost is extremely low, advantages such as reliability height. And the utility model discloses a technology and integrated circuit process are compatible, simple process, and the sensing element yield is high, has the potentiality of high integration level.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic three-dimensional structure diagram of a sensitive layer provided by an embodiment of the present invention;

fig. 2 is a schematic diagram of a three-dimensional structure of the back of the sensitive layer according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a cover plate according to an embodiment of the present invention;

fig. 4 is a top view of a sensitive layer provided by an embodiment of the present invention;

FIG. 5 is a sectional view taken along line A-A of FIG. 4;

fig. 6 is a schematic structural diagram of a heater according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a thermistor according to an embodiment of the present invention;

icon: the device comprises a 1-sensitive layer, a 2-heater, a 3-heater, a 4-heater, a 5-heater, a 6-heater, a 7-heater, an 8-heater, a 9-heater, a 10-thermistor, an 11-thermistor, a 12-thermistor, a 13-thermistor, a 14-thermistor, a 15-thermistor, a 16-thermistor, a 17-thermistor, an 18-cover plate, a 19-thermistor, a 20-thermistor, a 21-thermistor, a 22-thermistor, a 23- 'cross' -shaped groove, a 25-TaN material resistance block, a 26-TaN material resistance block, a 27-heavily doped n-type GaAs material resistance block and a 28-heavily doped n-type GaAs material resistance block.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings. It is to be understood that the description of the embodiments herein is for purposes of illustration and explanation only and is not intended to limit the invention.

With reference to fig. 1-5, the present embodiment provides a cross-shaped push-pull micro-mechanical three-axis membrane gyroscope, which comprises a sensitive layer 1 and a cover plate 18, wherein,

four pairs of heaters and six pairs of thermistors which are in a cross-shaped structure are arranged on the upper surface of the sensitive layer 1, and a cross-shaped groove 23 is etched on the lower surface of the sensitive layer; the thickness of the sensitive layer main body is very thin by arranging the cross-shaped groove 23, and the sensitive layer main body is of a silicon thin film structure, so that heat diffusion of working heat flow in the sealing cavity is facilitated.

two thermistors for detecting the angular velocity of the X axis are arranged symmetrically along the X axis direction of the cross-shaped structure and are vertical to the Y axis direction, namely a thermistor 19 and a thermistor 20; two thermistors for detecting the angular velocity of the Y axis are arranged symmetrically along the Y axis direction of the cross-shaped structure and are vertical to the X axis direction, namely a thermistor 21 and a thermistor 22; eight thermistors for detecting the angular speed of the Z axis are arranged on the X/Y direction of each measuring unit of the cross-shaped structure and are vertical to the direction of the heater, namely a thermistor 10, a thermistor 11, a thermistor 12, a thermistor 13, a thermistor 14, a thermistor 15, a thermistor 16 and a thermistor 17;

two pairs (heater 6, heater 7, heater 8 and heater 9) of the four pairs of heaters are placed in the X-axis direction and are perpendicular to the X-axis; the other two pairs (heater 2, heater 3, heater 4 and heater 5) are placed in the Y-axis direction and perpendicular to the Y-axis;

the four pairs of heaters are powered on in a periodic push-pull mode, namely one working period of the heaters comprises pulse voltage excitation time and power-off interval time; the electrifying mode of the thermistor is constant current;

and a groove is etched on the cover plate 18 and is hermetically connected with the upper surface of the sensitive layer 1.

In operation, four pairs of resistive heaters are used to heat the gaseous medium and promote directional movement of the gas stream along the X or Y axis. Each of the four pairs of heaters is driven by two square waves with the same frequency, the phase difference is 90 degrees, and the pulse duty ratio is 50 percent.

Specifically, the method comprises the following steps: in the sealed cavity, four pairs of heater resistors are electrified to generate joule heat, release heat to surrounding gas and carry out thermal diffusion to form moving thermal expansion flow; the square wave acting on the heaters alternately heats and cools each pair of heaters, thus forming a push-pull type heat flow between each pair of heaters. At the moment, the heater forms a cross-shaped push-pull heat flow, the push-pull heat flow has large flow rate, stable air flow state, high gyro sensitivity and good stability.

On the upper surface of the cross-shaped sensitive layer, 12 thermistors, namely a thermistor for detecting the angular velocity of an X axis, a thermistor for detecting the angular velocity of a Y axis and a thermistor for detecting the angular velocity of a Z axis, are used for detecting the change of the ambient air temperature caused by the input of the external angular velocity.

Specifically, when the Z-axis angular velocity is input from the outside, the moving thermal expansion flow deflects correspondingly due to the Cogowski force principle, the temperature of the thermistor deflected by the heat flow is higher than that of the thermistor parallel to the thermistor, and the two resistors which are relatively parallel generate temperature difference which is in direct proportion to the input Z-axis angular velocity; according to the metal thermal resistance effect, two thermistor which are relatively parallel generate resistance value difference, the detected resistance value difference is converted into voltage difference through a Wheatstone bridge circuit, and then the magnitude of the external Z-axis angular velocity can be calculated through the temperature difference and the voltage difference.

When the angular speed of the X axis is input from the outside, the moving thermal expansion flow deflects correspondingly due to the Cogowski force principle, the hot air flows generated by the two heaters in the X axis direction reach the two thermistor which are parallel relatively and correspond to the measuring unit along the opposite direction to form the opposite heating effect, and the two thermistor which are parallel relatively generate the temperature difference which is in direct proportion to the input angular speed of the X axis; according to the metal thermal resistance effect, two thermistor which are relatively parallel generate resistance value difference, the detected resistance value difference is converted into voltage difference through a Wheatstone bridge circuit, and then the magnitude of the external X-axis angular velocity can be calculated through the temperature difference and the voltage difference.

When the Y-axis angular velocity is input from the outside, the moving thermal expansion flow deflects correspondingly due to the Cogowski force principle, the hot air flows generated by the two heaters in the Y-axis direction reach the two parallel thermistors of the corresponding measuring unit along the opposite direction to form the opposite heating effect, and the two parallel thermistors generate the temperature difference which is in direct proportion to the input Y-axis angular velocity; according to the metal thermal resistance effect, two thermistor which are relatively parallel generate resistance value difference, the detected resistance value difference is converted into voltage difference through a Wheatstone bridge circuit, and then the magnitude of the external Y-axis angular velocity can be calculated through the temperature difference and the voltage difference.

In this embodiment, as a further technical solution, each pair of the heaters is driven by two square wave signals with the same frequency, the phase difference is 90 degrees, and the pulse duty ratio is 50%. The resistance is energized to generate joule heat, which releases heat to the surrounding gas to perform heat diffusion to form heat flow, and square waves act on the heaters to alternately heat and cool each pair of heaters, so that a push-pull type heat flow is formed between each pair of heaters. The four pairs of heaters form a cross-shaped distribution of heat flow. The push-pull type heat flow has the advantages of large flow rate, stable airflow state, high gyro sensitivity and good stability. The square wave driving heater is divided into two stages, in the first stage, the heater 2, the heater 5, the heater 6 and the heater 9 are heated through channels, the heater 3, the heater 4, the heater 7 and the heater 8 are not electrified and are at the ambient temperature, and four orthogonal hot air flows are generated. In the second stage, the heater 3, the heater 4, the heater 7 and the heater 8 are electrified for heating, the heater 2, the heater 5, the heater 6 and the heater 9 are not electrified and are at the ambient temperature, and four orthogonal cross-shaped hot air flows opposite to the first stage are generated between the two heaters. The working principle of the three-axis heat flow gyroscope is described by taking the first stage as an example. When there is an angular velocity input Ω Z in the Z-axis direction, the heat flow generated between the heater 2 and the heater 3 will be deflected in the YOX plane due to Coriolis force principle, and the thermistor temperature deflected by the heat flow is higher than the thermistor parallel to it, so that the two relatively

parallel thermistors

10 and 11, 12 and 13, 14 and 15, 16 and 17 generate a temperature difference proportional to the input angular velocity Ω Z. If the angular velocity Ω X is input in the X-axis direction, the hot air flow between the heaters 2 and 3 and the hot air flow between the heaters 4 and 5 reach the two

parallel thermistors

19 and 20 in opposite directions in the ZOY plane due to the coriolis force, and opposite heating effects are also formed in the plane formed by the thermistors, and a temperature difference proportional to the input angular velocity Ω X is generated between the two

parallel thermistors

19 and 20. If the sensitive angular velocity Ω Y is input in the Y-axis direction, due to the coriolis force principle, the hot air flow between the heater 6 and the heater 2 and the hot air flow between the heater 9 and the heater 8 reach the two

thermistor

21 and 22 in parallel in the ZOY plane in opposite directions, and opposite heating effects are also formed in the plane formed by the thermistors, and a temperature difference proportional to the input angular velocity Ω Y is generated between the two thermistor 21 and the thermistor 22 in parallel. The three pairs of

thermistors

19 and 20, the

thermistors

21 and 22, and the

thermistors

10 and 11 are respectively connected into two equal arms of a Wheatstone bridge, heating causes the resistance of a hot wire to change, and the change of the resistance is converted into three voltages Vx, Vy and Vz which are in direct proportion to angular velocities omega x, omega y and omega z through the Wheatstone bridge to output, so that the angular velocities in three orthogonal directions (X, Y, Z) are sensed.

In the embodiment, as a further technical scheme, the outer edge of the cross-shaped groove is larger than the outer contours of the upper surface heater and the thermistor to form a thin film structure, so that the heat diffusion of the gas medium in the sealed cavity is increased.

In this embodiment, as a further technical solution, the height of the cross-shaped groove is 2/3 to 3/4 of the height of the whole sensitive layer.

In this embodiment, as a further technical solution, the depth of the groove etched on the cover plate is 50 μm to 100 μm.

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 15 μm to 20 μm.

In this embodiment, as a further technical solution, the width of the measuring unit is 1/6 to 1/5 of the width of the whole sensitive layer.

In this embodiment, as a further technical solution, the heater is made of a resistance wire of TaN material with high temperature coefficient, as shown in fig. 6-7; the thermistor is composed of heavily doped n-type GaAs material resistance wires. Wherein the heater comprises 2 symmetrical resistive blocks 25, 26 of TaN material. The TaN material resistance block is composed of 4 series-connected resistors, and each resistor is specifically realized in the form of 4 parallel-connected TaN material resistance lines. By designing the TaN metal resistance wire in this way, the heater can generate more heat, thereby being beneficial to improving the sensitivity of gyro detection. The thermistor comprises 2

resistive blocks

27, 28 of symmetrically heavily doped n-type GaAs material. The heavily doped n-type GaAs material resistor block 27 is composed of 4 resistors connected in series, and each resistor is implemented in the form of 4 heavily doped n-type GaAs material resistor lines connected in parallel. By designing the GaAs thermistor in such a way, the thermistor can obtain larger voltage signal output, thereby being beneficial to improving the sensitivity of gyro detection.

The utility model discloses a "ten" style of calligraphy push-pull flows micromechanical triaxial film top can utilize GaAs-MMIC technique preparation to form, and concrete process flow is as follows:

the method comprises the following steps: preparation of doping Density of 10 on GaAs wafer¹⁸cm-³Etching the n + GaAs epitaxial layer to form an upper surface thermistor;

step two: sputtering TaN (tantalum nitride) layer as upper surface heater;

step three: respectively sputtering Ti/Au/Ti and etching to form

Thick pads and sensitive resistance lines;

step four: etching the cover plate groove and the cross-shaped groove on the lower surface of the sensitive layer, wherein the two silicon-based materials are not etched completely, so that the grooves and the grooves on the lower surface of the sensitive layer are prepared;

step five: the upper cover plate and the sensitive layer are bonded through a bonding process, so that the working environment of the gas medium is sealed;

step six: and packaging the processed structure to form the cross-shaped push-pull flow micro-mechanical three-axis film gyroscope.

In summary, the sensing element of the gyroscope provided by the utility model has no cantilever beam structure, and has the advantages of large impact resistance, simple structure, extremely low cost, high reliability and the like; and the thickness of the sensitive layer main body is very thin by arranging the cross-shaped groove 23, and the sensitive layer main body is of a silicon thin film structure, so that the heat diffusion of working heat flow in the sealing cavity is facilitated. The utility model discloses a technology and integrated circuit technology are compatible, will draw the circuit preparation to have the potentiality of high integration on a chip very easily. Because the sensitive mass of the sensor does not contain a solid mass block, compared with micro inertial sensors with other working principles, the sensor has the advantages of large impact resistance, simple structure, extremely low cost and high reliability.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims

1. A cross-shaped push-pull flow micro-mechanical three-axis film gyroscope is characterized by comprising a sensitive layer and a cover plate, wherein,

2. The cross-shaped push-pull flow micromechanical triaxial membrane gyroscope of claim 1, wherein each pair of heaters is driven by two square wave signals of the same frequency, the phase difference is 90 degrees, and the pulse duty cycle is 50%.

3. The cross-shaped push-pull flow micromechanical triaxial membrane gyroscope of claim 1, wherein the outer edges of the cross-shaped grooves are larger than the outer contours of the upper surface heater and the thermistor.

4. The cross-shaped push-pull micromechanical triaxial membrane gyroscope of claim 1, wherein the height of the cross-shaped groove is 2/3-3/4 of the total sensitive layer height.

5. The cross-shaped push-pull flow micromechanical triaxial film gyroscope according to claim 1, wherein the depth of the grooves etched on the cover plate is 50 μm to 100 μm.

6. The cross-shaped push-pull micromechanical triaxial membrane gyroscope according to claim 1, wherein the heater and thermistor on the upper surface of the sensitive layer have a height of 15 μm to 20 μm.

7. The cross-shaped push-pull micromechanical triaxial membrane gyroscope of claim 1, wherein the width of the measuring unit is 1/6-1/5 of the width of the entire sensitive layer.

8. The cross-shaped push-pull micromechanical triaxial membrane gyroscope of claim 1, wherein the heater is formed by a resistive wire of TaN material with a high temperature coefficient.

9. The cross-shaped push-pull flow micromechanical triaxial film gyroscope of claim 1, wherein the thermistor is formed by heavily doped n-type GaAs material resistor wires.