CN102980566A - Conical ring fluctuation micromechanical gyroscope and preparation method thereof - Google Patents

Abstract

The invention discloses a conical annular wave micromechanical gyroscope and a preparation method thereof, comprising: a base; a metal conical ring resonator; a piezoelectric film arranged on the inner wall of the metal conical ring resonator, and the piezoelectric film contains driving electrodes; two One detection electrode evenly distributed around the conical ring of the metal conical ring resonator; two balance electrodes evenly distributed around the conical ring of the metal conical ring resonator; four monitoring electrodes evenly distributed around the conical ring of the metal conical ring resonator; The metal conical ring resonator and eight electrodes form eight capacitors with air as the dielectric. The invention utilizes the four-antinode vibration mode of the conical ring to work, applies an AC voltage to the driving electrode, generates vibration by the inverse piezoelectric effect, and drives the conical ring resonator to vibrate in the driving mode. When there is an input angular velocity, the mode shape of the conical ring resonator changes to the detection mode, and the input angular velocity signal is processed by using the change of the capacitance gap formed between the detection electrode and the metal conical ring resonator.

Description

Conical ring wave micromechanical gyroscope and its preparation method

technical field

The invention relates to a solid-wave gyroscope in the field of micro-electromechanical technology, in particular, it is a piezoelectric-driven capacitive-detection conical ring micro-mechanical gyroscope based on the solid-wave principle and a preparation method thereof.

Background technique

Gyroscope is an inertial device that can be sensitive to the angle or angular velocity of the carrier, and it plays a very important role in the fields of attitude control, navigation and positioning. With the development of national defense technology and aviation and aerospace industries, the requirements of inertial navigation systems for gyroscopes are also developing in the direction of low cost, small size, high precision, multi-axis detection, high reliability, and adaptability to various harsh environments. The micro gyroscope based on MEMS technology is processed by micro-nano batch manufacturing technology, its cost, size, and power consumption are very low, and its environmental adaptability, working life, reliability, and integration are greatly improved compared with traditional technologies. Therefore, MEMS micro-gyroscope has become an important direction of extensive research and application development of MEMS technology in recent years.

Solid wave is a kind of mechanical fluctuation in a solid, which propagates the deformation caused by a certain point or part of the solid to be disturbed by force or other reasons, such as volume deformation or shear deformation, to other parts of the solid in the form of waves. In the process of wave propagation, the particle in the solid does not produce permanent displacement except for a small vibration in its original position. Because the solid is elastic, the elastic force has the ability to restore the deformation caused by the disturbance to the state without deformation, so the wave is formed. Elasticity is the main reason why waves can form in solids.

After searching the literature of the prior art, it was found that the Chinese patent "Resonator of Solid Wave Gyro and Solid Wave Gyro" (patent application number: CN201010294912.6) uses high-performance alloys to produce a cup-shaped vibrator by mechanical precision machining. The solid wave gyroscope, the chassis of the cup-shaped vibrator is bonded with piezoelectric sheets as the driving and detection electrodes, by applying a voltage signal of a certain frequency on the driving electrodes, the piezoelectric driving force is applied to the cup-shaped vibrator, and the vibrator is excited to generate a driving mode. Under the solid wave, when the angular velocity in the direction of the axis of the cup-shaped vibrator is input, the vibrator transforms to another degenerate detection mode solid wave under the action of the Coriolis force, and the phase difference between the two degenerate mode solid waves is certain The change of the input angular velocity can be detected by detecting the change of the output voltage of the detection electrode on the chassis of the cup-shaped vibrator.

This technology has the following disadvantages: the volume of the solid wave gyro cup-shaped resonator is too large, which limits its application in many conditions where the volume must be small; the piezoelectric electrodes of the cup-shaped vibrator chassis are bonded to the cup-shaped vibrator. There is a possibility of falling off under high-frequency vibration, and the reliability is not high; the processing technology of the gyroscope is relatively complicated, and the processing cost is high, so it is not suitable for mass production.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the above-mentioned designs, and provide a high-frequency solid-wave conical annular wave micromechanical gyroscope with simple structure, small volume, impact resistance, high Q value, and no need for vacuum packaging and its preparation method. Suitable for mass production.

According to one aspect of the present invention, there is provided a conical annular wave micromechanical gyroscope, comprising:

a base;

a metal conical ring resonator disposed on the base;

One layer of piezoelectric film arranged on the inner wall of the metal conical ring resonator, the piezoelectric film contains driving electrodes;

Two detection electrodes uniformly distributed around the conical ring of the metal conical ring resonator;

two balanced electrodes uniformly distributed around the conical ring of the metal conical ring resonator; and

Four monitoring electrodes uniformly distributed around the conical ring of the metal conical ring resonator;

Wherein: the two detection electrodes and the two balance electrodes are arranged between the four monitoring electrodes at intervals, the eight electrodes and the metal conical ring resonators form eight capacitors respectively, and the electrodes and the resonators are respectively used as capacitor poles plate, with air acting as the dielectric.

In the present invention, the material of the metal conical ring resonator is copper, which is driven by the piezoelectric effect and detected by the gap change of the capacitance formed between the electrode and the metal resonator, and the lower end of the metal conical ring resonator is directly connected to the base.

In the present invention, the four monitoring electrodes, the two detecting electrodes and the two balancing electrodes, each electrode is a conical ring with an opening angle of 25°, and the included angle between adjacent electrodes is 20°.

In the present invention, the material of the four monitoring electrodes is metal copper, and the monitoring electrodes are arranged evenly in a circle, and are used to monitor whether the metal conical ring resonator is working under the driving mode shape.

In the present invention, the material of the two detection electrodes is metal, and the detection electrodes are arranged in an evenly divided circle, and are used to detect the radial vibration of the metal conical ring resonator caused by the angular velocity perpendicular to the base plane direction, that is, the z-axis direction.

In the present invention, the material of the two balanced electrodes is metal, and the balanced electrodes are arranged equally in a circle, and are used to restore the driving mode shape of the metal conical ring resonator, so that the gyroscope works in a force balance mode.

In the present invention, the metal conical ring resonator and the electrodes are layered on the glass substrate by electroplating, and the piezoelectric thin film is made by sputtering.

The invention uses the four-antinode vibration mode of the metal conical ring resonator as a reference vibration, and in this mode, the edge of the conical ring vibrates along the radial direction of the conical ring. By applying a sinusoidal AC voltage to the driving electrode of the piezoelectric film on the inner wall of the metal conical ring resonator, the piezoelectric film vibrates due to the inverse piezoelectric effect, thereby driving the metal conical ring resonator to vibrate in the driving mode, and the metal conical ring resonator Whether it works in the form of four-antinode vibration needs to be detected by a laser Doppler vibration tester. When there is an angular velocity input perpendicular to the base, under the action of Coriolis force, the resonance mode of the metal conical ring resonator will change from the driving mode to the detection mode, and the resonance amplitude of the detection mode is proportional to the magnitude of the input angular velocity. By detecting the capacitance change formed by the metal conical ring resonator and the detection electrode, the amplitude of the metal conical ring resonator in the detection mode can be obtained, and then the magnitude of the input angular velocity can be obtained.

According to another aspect of the present invention, a method for preparing the above-mentioned gyroscope is provided. The method adopts MEMS microfabrication technology, uses sacrificial layer technology to spin-coat thick photoresist on the substrate, uses the prepared mask to carry out photolithography, and then develops, graphics , and then repeatedly electroplate metal on the patterned photoresist mask to form metal conical ring resonators, monitoring electrodes, detection electrodes and balance electrodes; then use a sputtering process to deposit a layer of PZT piezoelectric film and electrodes; finally, Weld the peripheral circuit for the gyro prototype and perform final packaging to obtain the finished gyro chip.

Compared with the prior art, the present invention has the following beneficial effects:

1. Using the conical ring structure in the millimeter-scale size range, the resonator has relatively high stiffness and good impact resistance; 2. The conical ring structure has good symmetry and small frequency difference between modes, which can increase the gain of the gyroscope , to improve the sensitivity and facilitate the follow-up circuit design; 3. The drive mode and detection mode with exactly the same mode shape are adopted, so that the influence of temperature change on the drive mode and detection mode is the same, thus reducing the temperature sensitivity; 4. , Using MEMS processing technology, the gyroscope has a small structure and a wide range of applications, which is conducive to mass production.

Description of drawings

By referring to the following detailed description of the invention carried out in conjunction with the accompanying drawings, you can easily understand the various features and advantages of the present invention. In the accompanying drawings, the same reference numerals represent the same structural elements, wherein:

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

In the figure, 1 represents the glass substrate, 2 represents the metal conical ring resonator, 3 represents the PZT piezoelectric film (with driving electrodes), 4 represents the metal monitoring electrode, 5 represents the metal detection electrode, and 6 represents the metal balance electrode.

Fig. 2 is the ANSYS simulated vibration mode figure of an embodiment of the present invention, is the driving mode mode schematic diagram of the conical ring resonator of this invention;

Fig. 3 is the operating principle of an embodiment of the present invention;

Fig. 4 is the ANSYS simulation mode shape figure of an embodiment of the present invention, is the detection mode mode shape schematic diagram of the conical ring resonator of this invention;

5 is a schematic diagram of the contact between the piezoelectric film and the metal conical ring resonator according to an embodiment of the present invention;

In Fig. 5, 2 is a metal conical ring resonator, 3 is a PZT piezoelectric film, and 7 is a driving electrode.

Detailed ways

Below in conjunction with accompanying drawing, the embodiment of the present invention is described in detail: present embodiment is carried out under the premise of technical solution of the present invention, has provided detailed implementation mode and specific operation process, but protection scope of the present invention is not limited to following the embodiment.

As shown in Figure 1, this embodiment includes:

a base1;

A metal conical ring resonator 2 arranged on the base;

A layer of piezoelectric film 3 arranged on the inner wall of the metal conical ring resonator 2;

Two detection electrodes 5 evenly distributed around the conical ring of the metal conical ring resonator 2;

Two balanced electrodes 6 evenly distributed around the conical ring of the metal conical ring resonator 2; and

Four monitoring electrodes 4 evenly distributed around the conical ring of the metal conical ring resonator 2;

Wherein: the two detection electrodes 5 and the two balance electrodes 6 are spaced between the four monitoring electrodes 4, and the eight electrodes and the metal conical ring resonator 2 form eight capacitors, and the eight electrodes and The metal conical ring resonators 2 are respectively used as capacitor plates, and the air is used as a dielectric.

In this embodiment, the substrate 1 is a glass substrate.

In this embodiment, the four monitoring electrodes are evenly distributed around the metal conical ring resonator 2, and are used to monitor whether the metal conical ring resonator 2 is working in the driving mode shape.

In this embodiment, the two detection electrodes are evenly distributed around the metal conical ring resonator 2, and are used to detect the vibration of the metal conical ring resonator 2 detection mode caused by the angular velocity in the direction perpendicular to the base plane, that is, the z-axis direction.

In this embodiment, the two balanced electrode materials are equally divided into the circular distribution of the conical ring resonator 2, and are used to restore the driving mode shape of the conical ring resonator, so that the gyroscope works in a force balance mode.

In this embodiment, the material of the metal conical ring resonator 2 is metal copper. The invention uses a piezoelectric thin film for excitation. Piezoelectric materials generate an electric field under the action of an external force. Conversely, when the crystal expands or contracts under an applied voltage, this property is called the piezoelectric effect. The piezoelectric effect is due to charge asymmetry in the original unit of the crystal of certain materials, which leads to the formation of electric dipoles, and within the entire crystal, the superposition of these dipole effects produces a polarization of the entire crystal, thereby generating within the material electric field. Only crystals lacking a center of symmetry exhibit piezoelectric properties. Commonly used piezoelectric materials: quartz, piezoelectric ceramics (such as LiNbO3, BaTiO3), PZT (lead zirconate titanate), ZnO, PVDF (polyvinylidene fluoride), etc. In this embodiment, a piezoelectric material is used to obtain the maximum vibration displacement, a PZT material with a large piezoelectric coefficient is selected, and a piezoelectric thin film is fabricated by a sputtering process.

In this embodiment, the piezoelectric film 3 is sputtered on the inner wall of the metal conical ring resonator 2, and the piezoelectric film 3 adheres to the metal conical ring resonator 2. When the driving electrodes on the piezoelectric film 3 apply an AC voltage , the piezoelectric film 3 vibrates, thereby driving the metal conical ring resonator 2 to vibrate. When AC voltages of different frequencies are applied, the vibration forms generated by the metal conical ring resonator 2 are different. A laser Doppler vibration analyzer is used to detect multiple points on the circumference of the metal conical ring resonator 2 to determine whether the metal conical ring works in the form of four-antinode vibration.

In this embodiment, the material of the four monitoring electrodes 4 is metal, which is in the form of a conical ring with an opening angle of 25°, and equally divides the circumference of the metal conical ring resonator 2 (that is, it is located at the position where the circumference of the conical ring is quartered). The monitoring electrodes are used to monitor whether the metal conical ring resonator 2 starts to vibrate normally under the excitation of the driving electrodes. If the vibration in the driving mode does not meet the design requirements, the monitoring electrodes are used to adjust.

In this embodiment, the material of the two detection electrodes 5 is metal, which is in the form of a conical ring with an opening angle of 25°, and equally divides the circumference of the metal conical ring resonator 2 (that is, it is located at a diagonal position of the conical ring). Each detection electrode is used to detect the magnitude of the angular velocity in the direction perpendicular to the base plane (z axis).

In this embodiment, the material of the two balance electrodes 6 is metal, which is in the form of a conical ring with an opening angle of 25°, and equally divides the circumference of the metal conical ring resonator 2 (ie, it is located at a diagonal position of the conical ring). Each balance electrode is used to forcibly weaken the metal conical ring resonator 2 to detect the mode shape when the angular velocity is input, so that the metal conical ring resonator 2 is only driving the mode shape vibration.

As shown in FIG. 2 , the driving mode of the conical ring oscillator 1 is obtained by means of finite element analysis. By applying a sinusoidal voltage signal to the driving electrode of the piezoelectric film 3, the piezoelectric film will vibrate radially due to the inverse piezoelectric effect, thereby driving the metal conical ring resonator 2 to vibrate. By using a laser Doppler vibrometer Measure the frequency when the four-antinode resonance is reached, so as to know the working frequency of the metal conical ring resonator 2 .

As shown in FIG. 3 , it is a schematic diagram of the three-dimensional mode shape of the metal conical ring resonator 2 transitioning from the driving mode to the detection mode under the condition of an input angular velocity. When an angular velocity in the z-axis direction perpendicular to the base plane is input, the metal conical ring resonator 2 is subjected to Coriolis force under radial vibration, as shown in the schematic diagram. Under the action of Coriolis force, the vibration of the metal conical ring resonator 2 changes from the driving mode to the detection mode, and the vibration amplitude is proportional to the input angular velocity.

As shown in FIG. 4 , the detection mode of the metal conical ring resonator 2 is obtained by means of finite element analysis. When there is an angular velocity input in the z-axis direction perpendicular to the base plane, the metal conical ring resonator 2 generates a vibration of the detection mode shape, which is caused by measuring the distance between the two detection electrodes 5 and the metal conical ring resonator 2 The capacitance change can detect the magnitude of the angular velocity in the direction perpendicular to the surface of the substrate 1 (z axis).

As shown in FIG. 5 , the contact relationship between the piezoelectric film 3 and the metal conical ring resonator 2 . There is a layer of metal electrodes 7 on the piezoelectric film 3 . The lower layer of the piezoelectric film 3 is connected to the metal conical ring resonator 2 to ensure that the same potential is 0V; when the piezoelectric film vibrates, it can drive the metal conical ring resonator 2 to vibrate; the metal electrode 7 on the upper layer is connected to the metal conical ring resonator 2 isolated, as the driving electrode for the piezoelectric film 3 to be connected to an AC voltage. When the metal conical ring resonator 2 is connected to 0 potential and the upper electrode 7 of the piezoelectric film 3 is connected to an AC voltage, the metal conical ring resonator 2 vibrates.

The above-mentioned gyroscope in this embodiment is driven by PZT thin film, adopts MEMS microfabrication technology, uses sacrificial layer technology to spin-coat thick photoresist such as SU-8 on the substrate, uses the prepared mask to carry out photolithography, and then develops and patterns, and then The patterned photoresist mask is repeatedly electroplated with metal to form a metal conical ring resonator 2 , a monitoring electrode 4 , a detection electrode 5 and a balance electrode 6 . Then use the sputtering process to deposit a layer of PZT piezoelectric film and electrodes; finally, weld the peripheral circuit for the gyro prototype and perform final packaging to obtain the finished gyro chip.

The gyroscope of this embodiment is a high-frequency solid wave gyroscope: due to the increase of the resonant frequency by 2-3 orders of magnitude (to more than 100kHz), the mechanical (Brownian) low noise is reduced; by using the micromachining process, the piezoelectric material is reduced Bonding operations for improved accuracy. The advantages of the gyroscope of this embodiment: 1. smaller size; 2. larger bandwidth; 3. good impact resistance; 4. maintaining a high Q value at or near atmospheric pressure, which simplifies the packaging of the gyroscope and thus Manufacturing costs are reduced.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (10)

1. A conical annular wave micromachined gyroscope, characterized in that it comprises: a base; a metal conical ring resonator disposed on the base; One layer of piezoelectric film arranged on the inner wall of the metal conical ring resonator, the piezoelectric film contains driving electrodes; Two detection electrodes uniformly distributed around the conical ring of the metal conical ring resonator; two balanced electrodes uniformly distributed around the conical ring of the metal conical ring resonator; and Four monitoring electrodes uniformly distributed around the conical ring of the metal conical ring resonator; Wherein: the two detection electrodes and the two balance electrodes are spaced between the four monitoring electrodes, these eight electrodes and the metal conical ring resonator form eight capacitors, and the eight electrodes and the The metal conical ring resonators are respectively used as capacitor plates, and the air is used as a dielectric. 2. The conical ring wave micromechanical gyroscope according to claim 1, characterized in that the material of the conical ring resonator is metal, which is driven by the inverse piezoelectric effect of the piezoelectric film, and is driven by eight electrodes and the metal cone The gap change of the capacitance formed by the ring resonator is detected. 3. The conical ring wave micromechanical gyroscope according to claim 1, characterized in that the metal conical ring resonator and each electrode are layered on the substrate by electroplating, and the piezoelectric film is made of Manufactured by sputtering. 4. the conical ring wave micromachined gyroscope according to claim 1, is characterized in that four described monitoring electrodes, two described detection electrodes and two described balance electrodes, each electrode is the circle of opening angle 25 ° Ring structure, the angle between adjacent electrodes is 20°. 5. The conical ring wave micromechanical gyroscope according to any one of claims 1-4, characterized in that the materials of the four monitoring electrodes are metal, and are used to monitor whether the metal conical ring vibrator works in the driving mode vibration type. 6. according to any one of claim 1-4 described conical ring wave micromachined gyroscope, it is characterized in that described two detecting electrode materials are metal, be used for detecting the angular velocity that is perpendicular to described substrate plane direction i.e. z-axis direction Vibration caused by the metal conical ring resonator on the detection mode. 7. The conical ring wave micromechanical gyroscope according to any one of claims 1-4, characterized in that the two balance electrode materials are metal, used to restore the driving mode shape of the conical ring resonator, Make the gyroscope work in force balance mode. 8. The conical ring wave micromechanical gyroscope according to any one of claims 1-4, characterized in that the upper layer of the piezoelectric film has a layer of metal electrodes, and the lower layer of the piezoelectric film is connected with the metal conical ring resonator to ensure The same potential is 0V; when the piezoelectric film vibrates, the metal conical ring resonator is driven to vibrate; the metal electrode on the upper layer is isolated from the metal conical ring resonator, and is used as a driving electrode for the piezoelectric film to receive an AC voltage ; When the metal conical ring resonator is connected to 0 potential and the upper electrode of the piezoelectric film is connected to an AC voltage, the metal conical ring resonator vibrates. 9. The conical ring wave micromechanical gyroscope according to claim 8, characterized in that when the driving electrode of the piezoelectric film is applied with an AC voltage, vibration is generated by the inverse piezoelectric effect, thereby driving the metal conical ring resonator Vibration, using a laser Doppler vibrometer to detect the four-antinode vibration mode of the metal conical ring resonator, so that the metal conical ring resonator works in this vibration mode; when there is an input angular velocity, the The mode shape of the metal conical ring resonator changes to the detection mode, and the detection mode vibration sensitive signal of the metal conical ring resonator is detected by utilizing the gap change of the capacitance formed by the detection electrode and the metal resonator. 10. a preparation method for the described gyro of claim 1, is characterized in that: adopt MEMS micromachining technique, utilize sacrificial layer technique to spin coat thick photoresist on substrate, utilize the mask plate that makes to carry out photoetching, developing, patterning afterwards , and then repeatedly electroplate metal on the patterned photoresist mask to form metal conical ring resonators, monitoring electrodes, detection electrodes and balance electrodes; then use a sputtering process to deposit a layer of PZT piezoelectric film and electrodes; finally, for The gyro prototype welds the peripheral circuit and performs final packaging to obtain the finished gyro chip.

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