阅读说明：本技术 一种单热源对流式微机械z轴薄膜陀螺 (Single heat source convection type micro-mechanical Z-axis film gyroscope ) 是由 朴林华 李备 朴然 李美樱 王灯山 于 2020-06-24 设计创作，主要内容包括：本发明公开了一种单热源对流式微机械Z轴薄膜陀螺,包括敏感层和盖板,敏感层的上表面设置有呈“一”字型结构的两根加热器和两对热敏电阻,敏感层的下表面刻蚀有一“十”字型凹槽；一根加热器和一对热敏电阻构成一个测量单元；两个测量单元中间设有正方形的隔离电阻；两根加热器的通电方式为周期方波式通电；盖板上刻蚀有凹槽,且与敏感层的上表面密闭连接。本发明提出的基于热膨胀流的MEMS陀螺,可实现平面Z轴角速度的测量,具有很高的集成度。而且敏感层的下表面刻蚀出“十”字形凹槽,散热性好。基于这些优点它可以广泛应用于平台稳定系统,如照相机、摄像机等电子产品的稳定系统,所以其市场前景十分光明。(The invention discloses a single heat source convection type micro-mechanical Z-axis film gyroscope which comprises a sensitive layer and a cover plate, wherein the upper surface of the sensitive layer is provided with two heaters in a straight-line structure and two pairs of thermistors, and the lower surface of the sensitive layer is etched with a cross-shaped groove; a heater and a pair of thermistors constitute a measuring unit; a square isolation resistor is arranged between the two measuring units; the two heaters are electrified in a periodic square wave mode; the cover plate is etched with a groove and is hermetically connected with the upper surface of the sensitive layer. The MEMS gyroscope based on the thermal expansion flow can realize the measurement of the plane Z-axis angular velocity and has high integration level. And the lower surface of the sensitive layer is etched with a cross-shaped groove, so that the heat dissipation performance is good. Based on the advantages, the method can be widely applied to platform stabilization systems, such as stabilization systems of electronic products such as cameras, video cameras and the like, so that the market prospect is bright.)

1. A single heat source convection type micromechanical Z-axis film gyroscope is characterized by comprising a sensitive layer and a cover plate, wherein,

the upper surface of the sensitive layer is provided with two heaters in a straight-line structure and two pairs of thermistors, and the lower surface of the sensitive layer is etched with a cross-shaped groove;

defining the linear directions of the upper surface of the linear sensitive layer as X directions, the direction vertical to the linear direction is Y direction, and the height direction of the sensitive layer is Z direction; the arrangement directions of the heater and the thermistor are parallel or vertical to the X or Y direction; the two heaters and the two pairs of thermistors form a linear network and are arranged along the X coordinate axis; a heater and a pair of thermistors form a measuring unit, and the measuring unit and the thermistor form two measuring units;

four thermistors for detecting the angular velocity of the Z axis are symmetrically arranged along the Y axis direction of the I-shaped structure and are vertical to the Y axis direction;

the two heaters are symmetrically arranged in the X-axis direction and are vertical to the X-axis;

the two heaters are electrified in a periodic square wave 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.

2. The single heat source-to-flow micromachined Z-axis membrane gyroscope of claim 1, wherein each of the heaters is driven by a square wave signal of the same frequency, 18Hz with a 50% pulse duty cycle, and heater heating power of 70 mW.

3. The single heat source coupled flow micromechanical Z-axis membrane gyroscope of claim 1, wherein the outer edges of the cross-shaped grooves are larger than the outer contours of the top surface heater and the thermistor.

4. The single heat source coupled flow micromachined Z-axis membrane gyroscope of claim 1, wherein the depth of the "cross" shaped grooves is 2/3 to 3/4 of the total sensitive layer height.

5. The single heat source coupled flow micromechanical Z-axis thin film gyroscope of claim 1, wherein the grooves etched on the cover plate have a depth of 50 μm to 100 μm.

6. The single heat source-to-flow micromachined Z-axis thin film gyroscope of claim 1, wherein the height of the heater and thermistor on the upper surface of the sensitive layer is 15 to 20 μ ι η.

7. The single heat source-to-flow micromachined Z-axis membrane gyroscope of claim 1, wherein the width of the measurement cell is 1/6 to 1/5 of the entire width of the sensitive layer.

8. The single heat source-to-flow micromachined Z-axis thin film gyroscope of claim 1, wherein the heater is constructed of a resistive line of TaN material with a high temperature coefficient.

9. The single heat source-current micro-mechanical Z-axis thin film gyroscope of claim 1, wherein the thermistor is constructed of heavily doped n-type GaAs material resistance wire.

Technical Field

The invention belongs to the technical field of detecting angular velocity attitude parameters of a moving body by utilizing a Coriolis force deflection heat flow sensitive body, in particular relates to a single heat source convection type micro-mechanical Z-axis film gyroscope and a processing method thereof, and belongs to the field of inertia measurement.

Background

The micro inertial sensor based on the thermal expansion principle manufactured by the MEMS technology appears in the middle and later stages of the last 90 th century, has the advantages of mass production, low cost, small volume, low power consumption and the like, and is an ideal product of the micro inertial sensor with middle or low precision in the future. 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 based on the principle of Coriolis effect existing when a high-frequency vibration mass block is driven by a base to rotate, and is a micro rate gyroscope combining micro-electronics and micro-mechanics. The solid mass in the gyro sensor needs to be suspended by a mechanical elastic body to keep the self vibration. Such a spinning top is easily damaged by a slightly high acceleration shock, and requires a vacuum package for reducing damping, and is complicated in process and generates fatigue damage and vibration noise when operated for a long time.

The sensitive element of the micro inertial sensor based on the thermal expansion principle is gas, and the external angular velocity is obtained by sensing the difference of the fluid temperature acted by the angular velocity through the temperature sensor. Because the suspension mass and the vibration structure of the traditional acceleration sensor are not used, the high impact can be resisted, certain precision can be ensured, and the contradiction between high overload and high precision can be well solved. Meanwhile, the MEMS technology is adopted for processing, so that the micro-inertial sensor has the advantages of small volume, light weight, low cost and the like, and can be widely applied. The principle of the MEMS thermal expansion gyroscope is initiated internationally, has similar advantages to those of a thermal convection accelerometer, does not have complex suspension mass and vibration structure, and has the advantages of large impact resistance, small volume, light weight, low cost, batch production and the like. Based on the advantages, the method can be widely applied to platform stabilization systems, such as stabilization systems of electronic products such as cameras and video cameras, and the market prospect is bright; more importantly, the sensor can be combined with a thermal convection accelerometer to form large-impact-resistant inertial guidance and other applications, and the measuring range and the sensitivity are not limited by the traditional theory.

The sensitive working principle of the miniature thermal expansion gyroscope is to utilize the flow velocity of a convection field to realize angular velocity measurement. When the heater is heated under the action of driving voltage, the air above the heater is heated and rises, so that the air flows on two sides are supplemented, and the air flows in the direction close to the thermistor are generated. When no external angular velocity acts, the flow rates of the gas on the two sides of the thermistor are equal, the directions are opposite, the distribution of the convection field is completely symmetrical, the temperatures sensed by the temperature sensors are the same, and the output angular velocity of the detection circuit is zero. When an angular velocity signal in the Z direction is applied, coriolis acceleration in the Y direction is generated in the gas moving in the X direction. The acceleration makes the motion of the gas deviate in the Y direction, so that the temperature sensors at the symmetrical positions in the Y direction are changed differently, and the voltage which is in direct proportion to the input angular velocity is output through the Wheatstone bridge, so that the angular velocity value is obtained. Some thermal expansion gyros on the market can generate asymmetric gas flow fields under the condition of no angular velocity input, so that the angular velocity detection error is caused. Therefore, how to overcome the above problems becomes a technical problem that needs 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 forms the prior art already known to a person skilled in the art.

Disclosure of Invention

The invention aims to provide a single heat source convection type micro-mechanical Z-axis film gyroscope to solve the technical problems in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a single heat source convection type micro-mechanical Z-axis film gyroscope which comprises a sensitive layer and a cover plate, wherein the upper surface of the sensitive layer is provided with two heaters in a straight-line structure and two pairs of thermistors, and the lower surface of the sensitive layer is etched with a cross-shaped groove;

defining the linear directions of the upper surface of the linear sensitive layer as X directions, the direction vertical to the linear direction is Y direction, and the height direction of the sensitive layer is Z direction; the arrangement directions of the heater and the thermistor are parallel or vertical to the X or Y direction; the two heaters and the two pairs of thermistors form a linear network and are arranged along the X coordinate axis; a heater and a pair of thermistors form a measuring unit, and the measuring unit and the thermistor form two measuring units; (ii) a

Four thermistors for detecting the angular velocity of the Z axis are symmetrically arranged along the Y axis direction of the I-shaped structure and are vertical to the Y axis direction;

the two heaters are symmetrically arranged in the X-axis direction and are vertical to the X-axis;

the two heaters are electrified in a periodic square wave 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 frequency is 18Hz, the pulse duty ratio is 50%, and the heating power of the heaters is 70 mW.

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 depth 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.

By adopting the technical scheme, the invention has the following beneficial effects:

the single heat source convection type micro-mechanical Z-axis film gyroscope provided by the invention adopts the sensitive layer with the linear heater and the thermistor and is matched with the corresponding signal detection processing circuit, the simultaneous measurement of the space Z-axis angular velocity can be realized, the advantages of no solid sensitive mass block, vibration resistance, impact resistance and the like of the micro heat flow gyroscope are inherited, and the multi-degree-of-freedom measurement of the MEMS gyroscope based on the heat expansion flow is realized. The invention adopts MEMS technology for processing, and has the advantages of large impact resistance, small volume, light weight, extremely low cost, high reliability and the like. The technology adopted by the invention is compatible with the integrated circuit technology, the technology is simple, the yield of the sensitive element is high, and the potential of high integration level is realized.

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 description of the embodiments or 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 other drawings can be obtained by those skilled in the art without creative efforts.

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

FIG. 2 is a schematic diagram of a three-dimensional structure of the back surface of a 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 schematic diagram of a single heat source to a flow micromechanical Z-axis thin-film gyroscope according to an embodiment of the present invention;

FIG. 6 is a sectional view taken along line A-A of FIG. 4;

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

FIG. 8 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-cross-shaped groove, a 3-cover plate, a 4-heater, a 5-heater, a 6-thermistor, a 7-thermistor, an 8-thermistor, a 9-thermistor, a 10-isolation resistor, a 11-single-side heater, a 12-single-side thermistor, a 13-TaN material resistor block, a 14-TaN material resistor block, a 15-heavily doped n-type GaAs material resistor block and a 16-heavily doped n-type GaAs material resistor block.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within 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", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular 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 should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; 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 meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

With reference to fig. 1-6, the present embodiment provides a single heat source coupled micro-mechanical Z-axis thin film gyroscope according to the present invention, which includes a sensitive layer 1 and a cover plate 3, wherein,

the upper surface of the sensitive layer 1 is provided with two heaters in a straight-line structure and two pairs of thermistors, and the lower surface of the sensitive layer is etched with a cross-shaped groove 2; the thickness of the sensitive layer main body is very thin by arranging the cross-shaped groove 2, 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.

Defining the linear directions of the upper surface of the linear sensitive layer as X directions, the direction vertical to the linear direction is Y direction, and the height direction of the sensitive layer is Z direction; the arrangement directions of the heater and the thermistor are parallel or vertical to the X or Y direction; the two heaters and the two pairs of thermistors form a linear network and are arranged along the X coordinate axis; a heater and a pair of thermistors form a measuring unit, and the measuring unit is formed by two measuring units;

four thermistors for detecting the angular velocity of the Z axis are arranged symmetrically along the Y axis direction of the I-shaped structure and are vertical to the Y axis direction, namely a thermistor 6, a thermistor 7, a thermistor 8 and a thermistor 9;

two heaters (a heater 4 and a heater 5) are arranged in the X-axis direction and are vertical to the X-axis;

the two heaters are electrified in a periodic square wave 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 in the cover plate 3 and is hermetically connected with the upper surface of the sensitive layer 1.

In operation, two resistive heaters are used to heat the gaseous medium and promote directional movement of the gas stream along the X-axis. Each pair of the two heaters is driven by square wave signals with the same frequency, the frequency is 18Hz, the pulse duty ratio is 50 percent, and the heating power of the heaters is 70 mW.

Specifically, the method comprises the following steps: in the sealed cavity, two heaters are electrified to generate joule heat, and release heat to surrounding gas for heat 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 convective heat flow on each heater.

On the upper surface of the linear sensitive layer, four thermistors for detecting the angular velocity of the Z axis are used for detecting the change of the ambient air temperature caused by the input of the external angular velocity.

Specifically, when Z-axis angular velocity is input from the outside, due to the coriolis force principle, the moving thermal expansion flow is correspondingly deflected, the hot air flow generated by the two heaters in the X-axis direction reaches the two relatively parallel thermistors (thermistor 6, thermistor 7, thermistor 8 and thermistor 9) of the corresponding measuring unit in opposite directions, so as to form opposite heating effects, and the two relatively parallel thermistors generate temperature difference proportional 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 according to the temperature difference and the average value of the two voltage differences.

In this embodiment, as a further technical solution, each of the heaters is driven by a square wave signal with the same frequency, the frequency is 18Hz, the pulse duty ratio is 50%, and the heating power of the heater is 70 mW. The resistance is energized to generate joule heat, which releases heat to the surrounding gas for heat diffusion to form heat flow, which acts on the square wave on the heaters to alternately heat and cool each pair of heaters, thus forming a convective heat flow between each pair of heaters. The two heaters form heat flow distributed in a straight line shape.

Fig. 5 is a working principle diagram of a single heat source to the flow type micromechanical Z-axis film gyroscope. With angular velocity input omega in the Z-axis direction_zIn time, due to the Coriolis force principle, the heat flow generated between the heater 4 and the heater 5 will be deflected in the YOX plane, the thermistor to which the heat flow is deflected is at a higher temperature than the thermistor parallel to it, and thus the two pairs of opposing parallel thermistors 6 and 7, and thermistors 8 and 9 produce a difference in angular velocity Ω with respect to the input_zA proportional temperature difference. The two pairs of thermistors 6, 7, 8 and 9 are respectively connected into two equal arms of a Wheatstone bridge, the heating can change the hot wire resistance, and the change of the resistance value is converted into two equal arms with the angular velocity omega through the Wheatstone bridge_zProportional voltage V_zOutput (V)_zThe output of (c) is an average of the two bridge imbalance voltages), and is thus sensitive to Z-axis angular velocity.

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 depth of the cross-shaped groove is 2/3 to 3/4 of the whole height of the 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. 7-8; the thermistor is composed of heavily doped n-type GaAs material resistance wires. Wherein the heater comprises 2 symmetrical resistive blocks 13, 14 of TaN material. The TaN material resistance block consists of 4 series-connected resistors, and each resistor is specifically realized by comprising 4 parallel 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 symmetrical resistive blocks 15, 16 of heavily doped n-type GaAs material. The GaAs material resistance block is composed of 4 series-connected thermal resistors, and each thermal resistor is specifically realized in a mode that 4 heavily-doped n-type GaAs material resistance lines which are connected in parallel are included. 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 invention discloses a single heat source convection type micro-mechanical Z-axis film gyroscope which can be prepared by utilizing a GaAs-MMIC technology, and the specific 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 formThick 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 single heat source convection type micro-mechanical Z-axis film gyroscope.

In conclusion, the sensing element of the gyroscope provided by the invention 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 2, and the heat dissipation performance is good. The technology adopted by the invention is compatible with the integrated circuit technology, has high sensitivity and good stability, can realize the measurement of the Z-axis angular speed, and has very high integration level, small volume, low power consumption and low cost.

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; while the invention has been described in detail and with reference to the foregoing embodiments, it will 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; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.