CN212082384U - Single heat source cross flow type micro-mechanical three-axis film gyroscope - Google Patents
Single heat source cross flow type micro-mechanical three-axis film gyroscope Download PDFInfo
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- CN212082384U CN212082384U CN202021188138.6U CN202021188138U CN212082384U CN 212082384 U CN212082384 U CN 212082384U CN 202021188138 U CN202021188138 U CN 202021188138U CN 212082384 U CN212082384 U CN 212082384U
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Abstract
The utility model discloses a single heat source cross flow type 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 heaters in a cross-shaped structure and six pairs of thermistors, and the lower surface of the sensitive layer is etched with a cross-shaped groove; a heater, a pair of Z-axis thermistors and an X/Y-axis thermistor form a measuring unit; the energization mode of the four heaters is a periodic square wave energization mode; 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 thermal current of the STREAMING of "ten" style of calligraphy distribution, and this kind of STREAMING thermal current 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
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 single heat source cross flow type micro-mechanical triaxial film top is related to.
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 single heat source cross flow type micro-mechanical 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 single heat source cross flow type 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; the four heaters and the six pairs of thermistors form a cross network which is symmetrically arranged along two vertical coordinate axes of X, Y; a heater, a pair of thermistors and a thermistor in the X/Y direction form a measuring unit, and the measuring unit is formed by 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 of the four heaters are arranged in the X-axis direction and are vertical to the X-axis; the other two are arranged in the Y-axis direction and are vertical to the Y-axis;
the four 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 suspension heights of the four heaters are consistent and are all z1(ii) a The suspension heights of the thermistor for detecting the X-axis angular velocity, the thermistor for detecting the Y-axis angular velocity and the thermistor for detecting the Z-axis angular velocity are consistent, and are all Z2And satisfies the following conditions: z is a radical of1＜z2Namely, a height difference exists between the heater and the thermistor;
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.
As a further technical scheme, the range of the height difference between the heater and the thermistor is 50-100 um.
Adopt above-mentioned technical scheme, the utility model discloses following beneficial effect has:
the utility model provides a single heat source cross flow type micro-mechanical 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 the simultaneous measurement of 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 of the MEMS top based on the thermal expansion flows. 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 working schematic diagram provided by the 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: 1-sensitive layer, 2- 'cross' -shaped groove, 3-cover plate, 4-heater, 5-heater, 6-heater, 7-heater, 8-Z-axis thermistor, 9-Z-axis thermistor, 10-Z-axis thermistor, 11-Z-axis thermistor, 12-Z-axis thermistor, 13-Z-axis thermistor, 14-Z-axis thermistor, 15-Z-axis thermistor, 16-X-axis thermistor, 17-X-axis thermistor, 18-Y-axis thermistor, 19-Y-axis thermistor, 20-isolation resistor, 21-single-side heater, 22-single-side thermistor, 23-TaN material resistor block, 24-TaN material resistor block, 25-heavily doped n-type GaAs resistor material block, 26-heavily doped n-type GaAs material resistor 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. 1-6, the present embodiment provides a single heat source cross-flow micro-mechanical three-axis membrane gyroscope, which includes a sensitive layer 1 and a cover plate 18, wherein,
four 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 2 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 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 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; the four heaters and the six pairs of thermistors form a cross network which is symmetrically arranged along two vertical coordinate axes of X, Y; the heater, the pair of Z-axis thermistors and the X/Y-axis thermistor form a measuring unit, and four measuring units are formed by the heater, the pair of Z-axis thermistors and the X/Y-axis thermistors;
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 16 and a thermistor 17; two thermistors for detecting the angular velocity of the Y axis are arranged symmetrically along the Y axis direction of the cross-shaped structure, namely a thermistor 18 and a thermistor 19, and are vertical to the X axis direction; eight thermistors for detecting the angular velocity 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, namely a thermistor 8, a thermistor 9, a thermistor 10, a thermistor 11, a thermistor 12, a thermistor 13, a thermistor 14 and a thermistor 15;
two of the four heaters (heater 4 and heater 6) are placed in the X-axis direction and perpendicular to the X-axis; the other two (heater 5 and heater 7) are placed in the Y-axis direction and perpendicular to the Y-axis;
the four 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;
the suspension heights of the four heaters are consistent and are all z1(ii) a The suspension heights of the thermistor for detecting the X-axis angular velocity, the thermistor for detecting the Y-axis angular velocity and the thermistor for detecting the Z-axis angular velocity are consistent, and are all Z2And satisfies the following conditions: z is a radical of1＜z2Namely, a height difference exists between the heater and the thermistor;
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, four resistive heaters are used to heat the gaseous medium and promote directional movement of the gas stream along the X or Y axis. Each heater is driven by two square waves with the same frequency, the frequency is 18Hz, the pulse duty ratio is 50 percent, and the heating power of the heater is 70 mW.
Specifically, the method comprises the following steps: in the sealed cavity, four heater resistors are electrified to generate joule heat, and the joule heat releases heat to surrounding gas to carry out thermal diffusion so as 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 between each pair of heaters. At the moment, the heater forms cross-shaped distributed convection heat flow, the flow rate of the convection heat flow is large, the air flow state is stable, the sensitivity of the gyroscope is high, and the stability is good.
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 with deflected heat flow is higher than that of the thermistor parallel to the thermistor, and the two thermistors (thermistors 8-15) 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 flow generated by the two heaters (the heater 5 and the heater 7) in the X axis direction reaches the two thermistors (the thermistor 16 and the thermistor 17) which are relatively parallel and correspond to the measuring unit along the opposite direction, so that the opposite heating effect is formed, and the temperature difference which is in direct proportion to the input angular speed of the X axis is generated by the two resistors which are relatively parallel; 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 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 flow generated by the two heaters (the heater 4 and the heater 6) in the Y-axis direction reaches the two parallel thermistors (the thermistor 18 and the thermistor 19) of the corresponding measuring unit along opposite directions to form opposite heating effects, and the two parallel thermistors generate 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 of the 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 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 four heaters form cross-shaped distributed convection heat flow. The convection type heat flow has large flow rate, stable airflow state, high sensitivity of the gyroscope and good stability.
The square wave driving heater operates in two cases, namely when the angular velocity omega is input in the X-axis directionxInputting angular velocity omega in Y-axis directionyAnd input angular velocity Ω in the Z-axis directionz. When the angular velocity omega is inputted in the X-axis directionxWhen the temperature is higher than the set temperature, the heater 5 and the heater 7 are electrified for heating, the heater 4 and the heater 6 are not electrified and are at the ambient temperature, and two opposite hot air flows along the Y-axis direction are generated. When the angular velocity omega is inputted in the Y-axis directionyWhen the heater 4 and the heater 6 are electrified for heating, the heater 5 and the heater 7 are not electrified and are at the ambient temperature, and two opposite hot air flows along the X-axis direction are generated between the two heaters. When the angular velocity omega is input in the Z-axis directionzWhen the heater 4, the heater 5, the heater 6 and the heater 7 are electrified and heated, the resistors are electrified to generate joule heat, the joule heat releases heat to surrounding gas, heat diffusion is carried out, four oscillating heat flows distributed in a cross shape are formed, and the tail ends of the heat flows are rectangular isolation resistors.
Fig. 5 is a working principle diagram of a single heat source cross-flow type micro-mechanical three-axis membrane gyroscope. With angular velocity input omega in the Z-axis directionzIn the meantime, due to the Coriolis force principle, the heat flow generated between the heater 4, the heater 5, the heater 6 and the heater 7 is deflected in the YOX plane, and the thermistor temperature of the heat flow deflection is higher than that of the thermistor parallel thereto, so that the two thermistors 8 and 9, 10 and 11, 12 and 13, 14 and 15, which are relatively parallel, generate a constant angular velocity Ω to the input angular velocity ΩzA proportional temperature difference. If the angular velocity Ω is inputted in the X-axis directionxDue to the fact thatThe hot air flow between the heater 5 and the heater 7 reaches the two parallel thermistors 16 and 17 along the opposite direction in the ZOY plane under the action of the Cogowski force, and the opposite heating effect can be formed on the plane formed by the thermistors, so that the input angular velocity omega is generated on the two parallel thermistors 16 and 17xA proportional temperature difference. If sensitive angular velocity omega is input in Y-axis directionyDue to the Cogowski force principle, the hot air flow between the heater 4 and the heater 6 reaches the two parallel thermistors 18 and 19 along the opposite directions in the ZOY plane, and the opposite heating effect can be formed on the plane formed by the thermistors, so that the input angular velocity omega is generated on the two parallel thermistors 18 and 19yA proportional temperature difference. Six pairs of thermistors 8 and 9, thermistors 10 and 11, thermistors 12 and 13, thermistors 14 and 15, thermistors 16 and 17, and thermistors 18 and 19 are respectively connected into two equal arms of a Wheatstone bridge, heating can change the resistance of the hot wire resistors, and the change of the resistance is converted into three equal arms of the Wheatstone bridge corresponding to the angular velocity omegax、Ωy、ΩzProportional voltage Vx、VyAnd VzOutputs and thereby senses angular velocity in three orthogonal directions (X, Y, Z).
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 23, 24 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 symmetrical resistive blocks 25, 26 of heavily doped n-type GaAs material. The GaAs material resistance block 25 is composed of 4 series-connected resistors, and each resistor is implemented in the form of 4 heavily-doped n-type GaAs material resistance 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 single heat source cross flow type micro-mechanical three-axis film gyroscope 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 single heat source cross-flow type 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 2, and the silicon thin film structure is beneficial to the heat diffusion of working heat flow in the sealing cavity. 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 (10)
1. A single heat source cross-flow type micro-mechanical three-axis film gyroscope is characterized by comprising a sensitive layer and a cover plate, wherein,
four 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; the four heaters and the six pairs of thermistors form a cross network which is symmetrically arranged along two vertical coordinate axes of X, Y; a heater, a pair of Z-axis thermistors and an X/Y-axis thermistor form a measuring unit, and four measuring units are formed by the heater, the pair of Z-axis thermistors and the X/Y-axis thermistors;
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 of the four heaters are arranged in the X-axis direction and are vertical to the X-axis; the other two are arranged in the Y-axis direction and are vertical to the Y-axis;
the four 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 suspension heights of the four heaters are consistent and are all z1(ii) a The suspension heights of the thermistor for detecting the X-axis angular velocity, the thermistor for detecting the Y-axis angular velocity and the thermistor for detecting the Z-axis angular velocity are consistent, and are all Z2And satisfies the following conditions: z is a radical of1＜z2Namely, a height difference exists between the heater and the thermistor;
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 cross-flow micromechanical triaxial membrane gyroscope of claim 1, wherein each of the heaters is driven by two square wave signals of the same frequency, the frequency is 18Hz, the pulse duty cycle is 50%, and the heater heating power is 70 mW.
3. The single heat source cross-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 single heat source cross-flow micromechanical triaxial membrane gyroscope of claim 1, wherein the depth of the "cross" shaped groove is 2/3-3/4 of the total sensitive layer height.
5. The single heat source cross-flow micromechanical triaxial film gyroscope of claim 1, wherein the depth of the grooves etched on the cover plate is 50 μ ι η to 100 μ ι η.
6. The single heat source cross-flow micromechanical triaxial membrane gyroscope of claim 1, wherein the height of the heater and thermistor on the upper surface of the sensitive layer is 15 μ ι η to 20 μ ι η.
7. The single heat source cross-flow micromachined tri-axial membrane gyroscope of claim 1, wherein the width of the measurement cell is 1/6 to 1/5 of the entire width of the sensing layer.
8. The single heat source cross-flow micromachined tri-axial membrane gyroscope of claim 1, wherein the heater is constructed of a resistive wire of TaN material with a high temperature coefficient.
9. The single heat source cross-flow micromechanical triaxial membrane gyroscope of claim 1, wherein the thermistor is constructed from heavily doped n-type GaAs material resistance wire.
10. The single heat source cross-flow type micromechanical triaxial film gyroscope of claim 1, wherein the height difference between the heater and the thermistor is in a range of 50-100 um.
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