CN113985057A - Dynamic heat source type omnibearing micro-mechanical angular velocity sensor and processing method thereof - Google Patents

Abstract

The invention discloses a dynamic heat source type omnibearing micro-mechanical angular velocity sensor and a processing method thereof, wherein the gyroscope comprises a substrate layer, an upper sensitive layer, a lower sensitive layer and a cover plate; an omnidirectional vibrator heater (dynamic heat source) is arranged at the central position of the upper sensitive layer, the omnidirectional vibrator heater is suspended at the central position of the upper sensitive layer through eight completely symmetrical semicircular supporting beams, and a circular middle heating cavity is arranged below the omnidirectional vibrator heater; the lower sensitive layer contains eight thermistors which are distributed in a regular octagon shape, and a rectangular middle detection cavity is arranged below the lower sensitive layer; the upper sensitive layer and the lower sensitive layer are bonded to form a sensitive layer; the electrifying mode of the heater is periodic alternating current; the cover plate is etched with a groove and is hermetically connected with the upper surface of the sensitive layer. The invention can realize the omnibearing measurement of the angular velocity, is not limited by the azimuth, has large measuring range, small measuring error and high detection accuracy, and has the characteristics of compact structure, easy intellectualization and integration and the like. Meanwhile, the novel anti-vibration and anti-impact device has the advantages of extremely low cost, high reliability and excellent anti-vibration and anti-impact performance.

Description

Dynamic heat source type omnibearing micro-mechanical angular velocity sensor and processing method thereof

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 omnibearing vibrator, in particular relates to a dynamic heat source type omnibearing micro-mechanical angular velocity sensor and a processing method thereof, and belongs to the field of inertia measurement.

Background

The Micro inertial sensor manufactured by using the 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-precision 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. At present, the market has higher and higher requirements on the capability of a micro gyroscope to adapt to harsh environment, and a micro fluid inertial sensor (MEMS inertial sensor) is unique in the MEMS sensor due to the ultrahigh impact resistance and ultralow manufacturing cost, and cannot be compared with other MEMS inertial sensors.

The micro fluid gyroscopes based on MEMS technology can be broadly classified into four types, 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 commercial micro-gyros of choice. The micro heat flow gyro (also called thermal expansion gyro) is a new micro fluid gyro which is proposed in recent years, a voltage-free electric sheet is not arranged in a sensitive element, high voltage is not required, and the micro heat flow gyro can be used in a gravity-free environment. Compared with the micro heat flow accelerometer (MEMS heat flow accelerometer) which is already commercialized, the MEMS heat flow gyroscope is not mature yet and still in the development stage. The difficulty of the MEMS heat flow gyroscope in practical application is that the sensitivity is lower than that of a micromechanical vibration gyroscope. In chinese patents 201410140298.6 and 201210130318.2, the micromechanical heat flow gyroscope is mostly based on the principle that the thermal expansion flow generated by the heater deflects under the coriolis force when the angular velocity is input, and the asymmetric distribution of the temperature field is detected by arranging a symmetrical thermistor. Because the velocity of hot air flow is very small, the gradient of asymmetric temperature field caused by deflection of air flow is very small, so that the unbalanced voltage output by the Wheatstone bridge formed by the thermistor is small, and the sensitivity of the sensor is low. In the conventional solution, although the sensitivity can be improved by increasing the heater power, the sensitivity is not substantially changed or improved due to the limitation of power consumption, and the bottleneck of practical use is difficult to break through.

Disclosure of Invention

The invention aims to provide a dynamic heat source type omnibearing micro-mechanical angular velocity sensor and a processing method thereof, which aim 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 dynamic heat source type omnibearing micro-mechanical angular velocity sensor, which comprises a substrate layer, an upper sensitive layer, a lower sensitive layer and a cover plate, wherein,

the center position of the upper sensitive layer is provided with an omnidirectional vibrator heater to form a dynamic heat source; the lower sensitive layer comprises eight thermistors, is positioned around the projection position of the omnibearing vibrator heater and is distributed in a regular octagon shape; the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer;

defining the length direction of the upper surface of the sensitive layer as an X direction, the width direction as a Y direction and the height direction as a Z direction; the omnibearing vibrator heater adopts a wind-fire wheel type sensitive structure, wherein the center of the omnibearing vibrator heater comprises a central wheel hub with a circular mass block, and the omnibearing vibrator heater is suspended at the central position of a sensitive layer through eight completely symmetrical semicircular supporting beams; a circular middle heating cavity is arranged below the heating cavity;

the omnidirectional oscillator heater can swing along any azimuth angle in an XOY plane of the sensitive layer besides the z axis vertical to the sensitive layer.

Two ends of the omnidirectional vibrator heater are covered with symmetrical electrodes along the X direction to form a movable resistance type heat source;

the eight thermistors are parallel to each other in pairs and are suspended on the surface of the lower sensitive layer, and a rectangular middle detection cavity is arranged below the thermistors; the eight thermistors form two angular velocity detection units, the four thermistors which are orthogonally and vertically distributed in a cross shape form one angular velocity detection unit, and each angular velocity detection unit can detect the angular velocities in two orthogonal vertical directions in an XOY plane;

the energization mode of the heater is periodic alternating current to generate alternating excitation voltage; the electrifying mode of the thermal resistor is constant current;

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

the cover plate and the substrate layer separate the gas media of the intermediate heating cavity and the intermediate detection cavity from the outside to form a sealed working system; the heights of the middle heating cavity and the middle detection cavity and the depth of the groove in the upper sealing layer are the total cavity height z, and z is more than or equal to 300 mu m and less than or equal to 1000 mu m;

as a further technical solution, the depth of the groove of the cover plate is 2/3 of the height of the cover plate.

As a further technical scheme, the height of the heater and the thermistor is 100nm to 1000 nm.

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

As a further technical scheme, the heater and the thermistor are both composed of metal layers consisting of a chromium adhesion layer and a platinum layer.

A method for processing the dynamic heat source type omnibearing micro-mechanical angular velocity sensor comprises the following specific process flows:

the method comprises the following steps: thermally oxidizing a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer;

step two: photoetching and forming a thermistor structure pattern on the silicon dioxide film;

step three: sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and the silicon dioxide in sequence by a magnetron sputtering process;

step four: stripping off the metal layer outside the thermistor structure pattern by adopting an ultrasonic stripping process to form a thermistor structure;

step five: etching off a part of silicon dioxide by adopting photoetching and wet etching processes;

step six: and (3) forming a groove with the depth of 300 mu m by adopting a silicon etching process, suspending and fixing the thermistor on the lower sensitive layer through a silicon dioxide film, and finishing the processing of the lower sensitive layer.

Step seven: thermally oxidizing a 0.5 μm thick silicon dioxide film on another N-type (100) single crystal silicon wafer;

step eight: photoetching the silicon dioxide film to form an omnidirectional oscillator heater structure pattern;

step nine: sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and the silicon dioxide in sequence by a magnetron sputtering process;

step ten: stripping off the metal layer outside the structure pattern of the omnidirectional oscillator heater by adopting an ultrasonic stripping process to form an omnidirectional oscillator heater structure;

step eleven: etching off a part of silicon dioxide by adopting photoetching and wet etching processes;

step twelve: etching and etching through by adopting a silicon etching process to form an intermediate heating cavity, so that the omnibearing vibrator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer of the gyroscope is finished;

step thirteen: bonding the lower sensitive layer and the upper sensitive layer through a bonding process;

fourteen steps: and bonding the cover plate and the upper sensitive layer by a bonding process to enable the upper surface of the sensitive layer to be positioned in the closed cavity, thereby finishing the processing of the gyroscope sensitive element.

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

1. the dynamic heat source type omnibearing micro-mechanical angular velocity sensor inherits the advantages of an MEMS heat flow gyro, and is small in size, light in weight and easy to intelligentize and integrate.

2. The sensitive structure of the gyroscope is a middle omnidirectional oscillator heater (dynamic heat source). The omnibearing vibrator is suspended in the center of the sensitive layer through eight completely symmetrical semi-circular support beams, the structure is firmer and more reliable, and the shock resistance of the sensor is improved. The omnidirectional vibrator can vibrate along the Z axis perpendicular to the rotating plane, and has the freedom degree of inertia force at any azimuth angle of the rotating plane. The sensitive structure can sense the input angular velocity of a rotating shaft (sensitive shaft) on any azimuth angle of an XOY plane, so that the omnibearing measurement of the angular velocity in the XOY plane is realized, the limitation of the azimuth angle is avoided, the measurement range is wide, the response speed is high, and the impact resistance is strong.

3. The omnidirectional vibrator adopts a wind-fire wheel type sensitive structure, and a central wheel hub is a mass block and also a heater. The sensitive structure of the wind-fire wheel type has the following advantages: the sensitive structure is adopted for central support, so that the structural stress is small; the structure has high symmetry, and the consistency of any azimuth angle detection can be realized; the wind-fire wheel type sensitive structure can realize that a relatively long elastic element and a relatively large mass block are manufactured in a small area, so that high inertia force sensitivity is obtained.

4. When the angular velocity is input around any azimuth angle along the carrier, the output voltage of the angular velocity is averaged and then output, the detection sensitivity is always kept at a constant value, the change caused by the difference of the azimuth angles is avoided, and meanwhile, the quadrant where the angular velocity is located and the azimuth angle can be accurately judged. Therefore, the sensor has small measurement error and high detection accuracy.

5. The sensitive element is manufactured on a silicon chip by the processes of photoetching, corrosion and the like, has good consistency, is convenient to introduce a microcomputer embedded system (singlechip) to carry out temperature compensation and nonlinear degree compensation, can improve the performance of the sensor, and can realize batch production.

6. The micro-gyroscope has the advantages of compact structure, extremely low cost, high reliability and excellent vibration and impact resistance, so that the micro-gyroscope can compete with a capacitive micro-mechanical vibrating gyroscope in the micro-gyroscope market with medium, low precision and low price.

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 sensor according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a two-layer structure of a sensor according to an embodiment of the present invention;

FIG. 3 is a schematic three-dimensional structure diagram of a cover plate according to an embodiment of the present invention;

FIG. 4 is a top view of a sensor provided by an embodiment of the present invention;

FIG. 5 is a top view of a lower sensitive layer of a sensor 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 diagram of the operation of an embodiment of the present invention;

FIG. 8 is a schematic diagram of an output circuit provided by an embodiment of the invention;

fig. 9 is a flowchart of a manufacturing process of the dynamic heat source type omni-directional micro-mechanical angular velocity sensor according to the embodiment of the present invention;

fig. 10 is a detection schematic diagram of a dynamic heat source type omni-directional micro-mechanical angular velocity sensor according to an embodiment of the present invention;

icon: 1-basal layer, 2-lower sensitive layer, 3-upper sensitive layer, 4-metal electrode, 5-middle heating cavity, 6-middle detection cavity, 7-cover plate, 8-groove, 9-omnibearing vibrator heater, 10-thermistor, 11-thermistor, 12-thermistor, 13-thermistor, 14-thermistor, 15-thermistor, 16-thermistor and 17-thermistor.

Detailed Description

The technical solutions 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. 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 those 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 in a specific orientation, and be operated, 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 meaning of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

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 intended for purposes of illustration and explanation only and are not intended to limit the scope of the invention.

Referring to fig. 1-6, the present embodiment provides a dynamic heat source type omni-directional micro-mechanical angular velocity sensor, which includes a substrate 1, an upper sensitive layer 3, a lower sensitive layer 2 and a cover plate 7, wherein,

an omnidirectional vibrator heater 9 is arranged at the central position of the upper sensitive layer 3 to form a dynamic heat source; the lower sensitive layer 2 comprises eight thermistors (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), is positioned around the projection position of the omnidirectional oscillator heater 9 and is distributed in a regular octagon shape; the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer;

defining the length direction of the upper surface of the sensitive layer as an X direction, the width direction as a Y direction and the height direction as a Z direction;

the omnibearing vibrator heater 9 adopts a wind-fire wheel type sensitive structure, the center of the omnibearing vibrator heater comprises a central wheel hub with a circular mass block, and the omnibearing vibrator heater is suspended at the central position of a sensitive layer through eight completely symmetrical semicircular supporting beams; a circular middle heating cavity 5 is arranged below the heating cavity;

the omnidirectional oscillator heater 9 can swing along any azimuth angle in an XOY plane of the sensitive layer besides the z axis vertical to the sensitive layer.

Two ends of the omnidirectional vibrator heater 9 are covered with symmetrical metal electrodes 4 along the X direction to form a movable resistance type heat source;

the thermistor 10, the thermistor 11, the thermistor 12, the thermistor 13, the thermistor 14, the thermistor 15, the thermistor 16 and the thermistor 17 are parallel to each other in pairs and are suspended on the surface of the lower sensitive layer, and a rectangular middle detection cavity 6 is arranged below the thermistor; the eight thermistors 10, 11, 12, 13, 14, 15, 16 and 17 form two angular velocity detection units;

the energization mode of the heater is periodic alternating current to generate alternating excitation voltage; the electrifying mode of the thermal resistor is constant current;

and a groove 8 is etched in the cover plate 7 and is hermetically connected with the upper surface of the upper sensitive layer 3.

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

In this embodiment, as a further technical solution, the omnidirectional oscillator heater 9 is driven by an alternating excitation voltage to generate an alternating temperature field, the oscillator generates an alternating thermal stress along the axial direction and the thickness direction of the oscillator, and at the same time, the oscillator is electrified to generate joule heat, which releases heat to the surrounding air to perform thermal diffusion and form a heat flow. When the frequency of the alternating current excitation signal is consistent with the vibration frequency of the vibrator along the thickness direction, the vibrator resonates in the thickness direction (Z-axis direction) to generate displacement, and the heat flow is driven to flow in the X-axis (Y-axis) direction.

In this embodiment, as a further technical solution, four thermistors 10, 11, 12, 13 orthogonally and vertically distributed in a cross shape constitute one angular velocity detection unit, and four thermistors 14, 15, 16, 17 orthogonally and vertically distributed in a cross shape constitute another angular velocity detection unit; each angular velocity detection unit is capable of measuring angular velocities in two orthogonal vertical directions within the XOY plane.

As shown in fig. 7, an angular velocity detection unit including a thermistor 10, a thermistor 11, a thermistor 12, and a thermistor 13 is exemplified. When the angular velocity Ω is inputted in the direction along the line connecting the thermistor 10 and the thermistor 11 (the X-axis direction)_XIn the meantime, the omnidirectional vibrator heater 9 is deflected in the Y-axis direction (Y-axis direction) in the YOX plane toward the connecting line direction (Y-axis direction) of the thermistor 12 and the thermistor 13 by the Coriolis force principle (Coriolis force), and the temperature of the thermistor to which the thermal vibrator is deflected is higher than that of the thermistor parallel thereto, so that the thermistor 12 and the thermistor 13 which are parallel to each other generate the angular velocity Ω with respect to the input angular velocity Ω_XA proportional temperature difference. In the figure, T1 to T8 correspond to the thermistor 10, the thermistor 11, the thermistor 12, the thermistor 13, the thermistor 14, the thermistor 15, the thermistor 16, and the thermistor 17, respectively.

As shown in FIG. 8, the thermistor 12 and the thermistor 13 are connected to two equal arms of two Wheatstone bridges to which the angular velocity Ω is input_XThe generated temperature difference is converted into the angular velocity omega through the change of the resistance value of a bridge arm of the Wheatstone bridge_XProportional voltage unbalance voltage V_XAnd outputting, thereby sensing the angular velocity in the X direction.

When the angular velocity Ω is inputted in the direction along the line connecting the thermistor 12 and the thermistor 13 (Y-axis direction)_YBecause of Coriolis force principle, the omnidirectional oscillator heater 9 will deflect in the YOX plane in the direction of the line connecting the thermistor 10 and the thermistor 11 in the X-axis direction (X-axis direction), and the temperature of the thermistor deflected by the thermal oscillator is higher than that of the thermistor parallel to the thermistor, so that the two parallel resistive thermistors 10 and 11 generate an angular velocity omega equal to the input angular velocity_YA proportional temperature difference. As shown in FIG. 8, the thermistor 10 and the thermistor 11 are connected to form two equal arms of two Wheatstone bridges to which the angular velocity Ω is input_YThe generated temperature difference is converted into the angular velocity omega through the change of the resistance value of a bridge arm of the Wheatstone bridge_YProportional voltage unbalance voltage V_YOutput and thus sense angular velocity in the Y direction. The thermistor 10, the thermistor 11, the thermistor 12, and the thermistor 13 constitute an angular velocity detection unit capable of measuring two angular velocities Ω perpendicular to each other_XAnd Ω_Y. Similarly, another angular velocity detection unit composed of the thermistor 14, the thermistor 15, the thermistor 16 and the thermistor 17 can sense the input angular velocity Ω_X1And Ω_Y1，Ω_X1Is the direction of the connection line between the thermistor 14 and the thermistor 15, omega_Y1The direction of the line connecting the thermistor 16 and the thermistor 17.

As shown in fig. 10, when the coordinate axis of the plane on which the sensor is located rotates around any azimuth (the azimuth angle is α) from X, Y to X ', Y', the angular velocity Ω to be measured input along the azimuth angle α is projected on the coordinate axes X 'and Y' to be Ω_X、Ω_Y，Ω_X、Ω_YThe relation with the angular speed Ω to be measured is:

by measuring omega_X、Ω_YCan know along either sideThe magnitude of the angular velocity of the azimuthal input is Ω. Omega here_X、Ω_YCan be obtained by the angular velocity detection unit described above. Omega output from the first angular velocity detecting unit_X、Ω_YCalculating the angular velocity input along any azimuth angle according to formula (1), and using omega₁And (4) showing. Omega output from the second angular velocity detecting unit_X1And Ω_Y1Calculating the angular velocity input along any azimuth angle according to the formula (1), and using omega₂And (4) showing. Get omega₁And Ω₂The average of (d) yields the magnitude of Ω:

thus forming a dynamic heat source type omnibearing micro-mechanical angular velocity sensor. The detection method can avoid errors caused by process reasons to a greater extent and improve the detection precision. The direction of the angular velocity can be judged by the resistance value changes of the eight thermistors, and in which quadrant the azimuth angle is.

In the embodiment, as a further technical scheme, the cover plate 7 and the substrate layer 1 isolate the gas media of the intermediate heating cavity 5 and the intermediate detection cavity 6 from the outside to form a sealed working system; the height of the middle heating cavity 5 and the middle detection cavity 6 and the depth of the groove 8 in the upper sealing layer are the total cavity height z, and z is more than or equal to 300 mu m and less than or equal to 1000 mu m; the total cavity height in this embodiment is hundreds of microns, and the natural convection motion of the gas flow in the cavity can be effectively inhibited, so that the influence of the Z-axis acceleration on the performance of the sensor can be greatly reduced. The total cavity height may be arbitrarily selected in the range of 300 microns to 1000 microns, depending on the requirements for gyroscope performance, for example the total cavity height in the above embodiment may be 700 microns.

In this embodiment, as a further technical solution, in order to increase the depth of the cover plate groove, the gas flowing space can be increased, thereby increasing the sensitivity of the sensor, and the depth of the groove 8 is 2/3 of the height of the cover plate 7.

In this embodiment, as a further technical solution, in order to form a more stable and reliable thin film resistor having a resistance value with a small change with temperature, the heights of the heater and the thermistor on the upper surface of the sensitive layer are 100nm to 1000 nm.

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

In this embodiment, as a further technical solution, the heater and the thermistor are each formed by a metal layer composed of a chromium adhesion layer and a platinum layer.

Referring to fig. 9, the dynamic heat source type omni-directional micro-mechanical angular velocity sensor disclosed by the present invention has the following manufacturing process:

step (a): a0.5 μm thick silicon dioxide film was thermally oxidized on an N-type (100) single crystal silicon wafer, as shown in FIG. 9 (a).

Step (b): the thermistor structure pattern is formed on the silicon dioxide film by photolithography, as shown in fig. 9 (b).

Step (c): a metal layer consisting of a chromium adhesion layer and a platinum layer was sequentially sputtered on the photoresist and the silicon dioxide by a magnetron sputtering process, as shown in fig. 9 (c).

Step (d): the metal layer outside the thermistor structure pattern is peeled off by an ultrasonic peeling process, as shown in fig. 9(d), to form a thermistor structure.

A step (e): a portion of the silicon dioxide is etched away using photolithography and wet etch processes, as shown in fig. 9 (e).

Step (f): and (3) forming a groove with the depth of 300 microns by adopting a silicon etching process, suspending and fixing the thermistor on the lower sensitive layer through the silicon dioxide film, and finishing the processing of the lower sensitive layer, as shown in fig. 9 (f).

Step (g): a0.5 μm thick silicon dioxide film was thermally oxidized on another N-type (100) single crystal silicon wafer as shown in FIG. 9 (g).

A step (h): an omnidirectional oscillator heater structure was formed on the silicon dioxide film by photolithography, as shown in fig. 9 (h).

Step (i): and (5) sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and the silicon dioxide in sequence by using a magnetron sputtering process, as shown in fig. 9 (i).

Step (j): and (5) stripping off the metal layer except the omnidirectional oscillator heater structure pattern by adopting an ultrasonic stripping process, and forming the omnidirectional oscillator heater structure as shown in (j) of fig. 9.

Step (k): a portion of the silicon dioxide is etched away using photolithography and wet etch processes, as shown in fig. 9 (k).

Step (l): and etching through a silicon etching process to form an intermediate heating cavity, so that the omnibearing vibrator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer of the gyroscope is finished, as shown in fig. 9 (l).

Step (m): the lower sensitive layer and the upper sensitive layer are bonded by a bonding process, as shown in fig. 9 (m).

And (n): and bonding the cover plate and the upper sensitive layer by a bonding process to enable the upper surface of the sensitive layer to be positioned in the closed cavity, thereby finishing the processing of the gyroscope sensitive element.

In summary, the invention breaks through the inherent mode of the previous research on the heat flow gyroscope, and provides a dynamic heat source type omnibearing micro-mechanical angular velocity sensor, which enables a heater with a very high temperature gradient to move, and enables the heater to deflect under the action of inertia force to form a large temperature gradient at a thermistor, thereby realizing high-sensitivity output. The omnibearing vibrator heater (dynamic heat source) is suspended in the center of the sensitive layer through eight completely symmetrical semicircular supporting beams, can realize omnibearing measurement of angular velocity, is not limited by azimuth angles, and has the advantages of wide measurement range, high response speed and strong impact resistance. The wind-fire wheel type sensitive structure has high structural symmetry and small structural stress, and can ensure the consistency of detection of any azimuth angle. When the angular velocity is input along the carrier around any azimuth angle, the output voltage of the angular velocity is averaged and then output, the detection sensitivity is always kept at a constant value, the change caused by the difference of the azimuth angles is avoided, and meanwhile, the quadrant where the angular velocity is located and the azimuth angle can be accurately judged. Therefore, the measurement error is small, and the detection accuracy is high. The structure can realize that a relatively long elastic element and a relatively large mass block are manufactured in a small area, so that high inertia force sensitivity is obtained. The sensitive element is manufactured on a silicon chip by the processes of photoetching, corrosion and the like, has good consistency, is convenient to introduce a microcomputer embedded system (singlechip) to carry out temperature compensation and nonlinear compensation, can improve the performance of the sensor, and can realize batch production. The dynamic heat source type omnibearing micro-mechanical angular velocity sensor not only inherits the advantages of an MEMS heat flow gyroscope, but also has the characteristics of compact structure, small volume, light weight, easy intellectualization and integration and the like, and accords with the development direction of the sensor towards microminiature, synthesis and intelligence. Meanwhile, the micro-gyroscope has the advantages of simple structure and processing technology, extremely low cost, high reliability and excellent vibration and impact resistance, so that the micro-gyroscope can compete with a capacitive micro-mechanical vibration gyroscope in the micro-gyroscope market with medium, low precision and low price.

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.

Claims (7)

1. A dynamic heat source type omnibearing micro-mechanical angular velocity sensor is characterized by comprising a substrate layer, an upper sensitive layer, a lower sensitive layer and a cover plate, wherein,

the center position of the upper sensitive layer is provided with an omnidirectional vibrator heater to form a dynamic heat source; the lower sensitive layer comprises eight thermistors, is positioned around the projection position of the omnibearing vibrator heater and is distributed in a regular octagon shape; the upper sensitive layer and the lower sensitive layer are bonded together to form a sensitive layer;

defining the length direction of the upper surface of the sensitive layer as an X direction, the width direction as a Y direction and the height direction as a Z direction; the omnibearing vibrator heater adopts a wind-fire wheel type sensitive structure, the center of the omnibearing vibrator heater comprises a central wheel hub with a circular mass block, and the omnibearing vibrator heater is suspended at the central position of a sensitive layer through eight completely symmetrical semicircular supporting beams; a circular middle heating cavity is arranged below the heating cavity;

the omnidirectional oscillator heater can swing along a z axis vertical to the sensitive layer and also can swing along any azimuth angle in an XOY plane where the sensitive layer is located;

two ends of the omnidirectional vibrator heater are covered with symmetrical electrodes along the X direction to form a movable resistance type heat source;

the eight thermistors are parallel to each other in pairs and are suspended on the surface of the lower sensitive layer, and a rectangular middle detection cavity is arranged below each thermistor; the eight thermistors form two angular velocity detection units, the four thermistors which are orthogonally and vertically distributed in a cross shape form one angular velocity detection unit, and each angular velocity detection unit can detect the angular velocities in two orthogonal vertical directions in an XOY plane;

the energization mode of the heater is periodic alternating current to generate alternating excitation voltage; the power-on mode of the thermistor is constant current;

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

2. The dynamic heat source type omni-directional micro-mechanical angular velocity sensor according to claim 1, wherein the cover plate and the substrate layer isolate the gas media of the intermediate heating cavity and the intermediate detection cavity from the outside to form a sealed working system; the height of the middle heating cavity and the middle detection cavity and the depth of the groove in the cover plate are the total cavity height z, and z is more than or equal to 300 mu m and less than or equal to 1000 mu m.

3. The dynamic heat source type omni-directional micro-machined sensor of angular velocity according to claim 1, wherein the groove depth of the cover plate is 2/3 of the cover plate height.

4. The sensor of claim 1, wherein the heater and thermistor have a height of 100nm to 1000 nm.

5. The sensor of claim 1, wherein the thermistor has a uniform length, which is 1/6-1/5 of the width of the entire lower sensitive layer.

6. The sensor of claim 1, wherein the heater and the thermistor are each formed by a metal layer comprising a chromium adhesion layer and a platinum layer.

7. A method for processing the dynamic heat source type omnibearing micro-mechanical angular velocity sensor as claimed in any one of claims 1 to 6, characterized in that the specific process flow is as follows:

the method comprises the following steps: thermally oxidizing a 0.5 μm thick silicon dioxide film on an N-type (100) single crystal silicon wafer;

step two: photoetching and forming a thermistor structure pattern on the silicon dioxide film;

step three: sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and the silicon dioxide in sequence by a magnetron sputtering process;

step four: stripping off the metal layer outside the thermistor structure pattern by adopting an ultrasonic stripping process to form a thermistor structure;

step five: etching off a part of silicon dioxide by adopting photoetching and wet etching processes;

step six: and (3) forming a groove with the depth of 300 mu m by adopting a silicon etching process, suspending and fixing the thermistor on the lower sensitive layer through a silicon dioxide film, and finishing the processing of the lower sensitive layer.

Step seven: thermally oxidizing a 0.5 μm thick silicon dioxide film on another N-type (100) single crystal silicon wafer;

step eight: photoetching the silicon dioxide film to form an omnidirectional oscillator heater structure pattern;

step nine: sputtering a metal layer consisting of a chromium adhesion layer and a platinum layer on the photoresist and the silicon dioxide in sequence by a magnetron sputtering process;

step ten: stripping off the metal layer outside the structure pattern of the omnidirectional oscillator heater by adopting an ultrasonic stripping process to form an omnidirectional oscillator heater structure;

step eleven: etching off a part of silicon dioxide by adopting photoetching and wet etching processes;

step twelve: etching and etching through by adopting a silicon etching process to form an intermediate heating cavity, so that the omnibearing vibrator heater is suspended and fixed on the upper sensitive layer through the silicon dioxide film, and the processing of the upper sensitive layer of the gyroscope is finished;

step thirteen: bonding the lower sensitive layer and the upper sensitive layer through a bonding process;

fourteen steps: and bonding the cover plate and the upper sensitive layer by a bonding process to enable the upper surface of the sensitive layer to be positioned in the closed cavity, thereby finishing the processing of the gyroscope sensitive element.

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