A MEMS inertial vibration system with a self-test function for motion postures and a preparation method thereof

Abstract

The present invention relates to the technical field of inertial sensors, and particularly relates to a MEMS inertial vibration system with a self-measuring function of motion posture and a preparation method, including: an inertial vibration platform that moves with multi-directional degrees of freedom, and the direction conforms to the cooperative bending vibration generated by the inertial vibration platform under a voltage excitation signal; a PMUT array that is arrayed at a preset interval on the bottom surface of the inertial vibration platform and is bonded to the bottom surface of the inertial vibration platform. The PMUT array includes a plurality of transmitting sub-arrays and a plurality of receiving sub-arrays, and the transmitting sub-arrays and the receiving sub-arrays correspond one by one. Each of the transmitting sub-arrays and the receiving sub-arrays includes a plurality of PMUT single tubes, and the plurality of PMUT single tubes are connected to each other to form a transmitting sub-array or a receiving sub-array. The beneficial technical effects of the present invention include: being able to perform self-monitoring of the motion state of the MEMS inertial vibration platform, providing a reference for the self-calibration of the MEMS inertial sensor, and simplifying the implementation method of self-calibration.

Description

Technical Field

[0001] The present invention relates to the technical field of inertial sensors, and particularly relates to a MEMS inertial vibration system with a self-measuring function of motion attitude and a preparation method thereof. Background Technique

[0002] The inertial navigation system is a navigation technology developed with the development of inertial sensors. When it works, it does not rely on other external information such as satellite signals, and has the advantages of complete autonomy, no interference, large amount of output information, and strong real-time performance of output information. Therefore, it occupies an important position in many high-precision application fields such as navigation, guided weapons, and robots.

[0003] Inertial sensors (such as accelerometers, gyroscopes, etc.) based on Micro-Electro-Mechanical System (MEMS) technology can provide multi-degree-of-freedom inertial information required for inertial positioning, and have the advantages of low cost, small volume, low power consumption, and strong anti-shock ability. Therefore, the research on MEMS inertial sensors has important supporting significance for the rapid development of unmanned system autonomous navigation technology and meeting the increasingly improved application requirements of navigation technology.

[0004] Piezoelectric Micromachined Ultrasonic Transducer (PMUT) is a type of MEMS device that vibrates a piezoelectric thin film through the direct and inverse piezoelectric effects of piezoelectric materials to emit or receive ultrasonic signals. A special feature of PMUT is that it can be used both as an actuator (emitting sound waves) and as a sensor (receiving sound waves). This greatly reduces the cost of PMUT devices from design to production, packaging, testing, and systemization. In addition to the cost advantage, the performance advantage of PMUT is also very prominent. Generally speaking, actuators and sensors are naturally reciprocal in key performance indicators. MEMS actuators that output large displacements are difficult to detect small vibrations, while precision sensing devices such as accelerometers and gyroscopes cannot output sufficient acceleration or angular velocity. However, as a standard device, the transmission and reception performance of PMUT is exactly at a moderate balance point. As an actuator, PMUT emits a relatively large sound pressure and vibration amplitude, and has a simple structure, with low design and process difficulty; while as a sensor, its sensitivity and signal-to-noise ratio are not low, and the challenges brought to the circuit and algorithm are not great.

[0005] However, currently, MEMS inertial sensors face the problem of long-term stability. For example, the scale factor of a MEMS accelerometer drifts continuously with the increase of working time, resulting in the need for the MEMS inertial sensor to be recalibrated irregularly, which additionally increases the working time. The zero-rate drift of a MEMS gyroscope has an impact on the growth of the position error of an inertial navigation system that is a cubic function of time, and the manufacturing of high-precision MEMS gyroscopes is difficult and costly. Therefore, it is necessary to study a MEMS inertial vibration system that can improve the accuracy of MEMS inertial sensors and reduce the calibration cost of MEMS inertial sensors.

[0006] For example, Chinese Patent CN108253952A, with a publication date of July 6, 2018, discloses a zero-rate self-calibrating MEMS gyroscope and its zero-rate self-calibrating method. Based on the working characteristics of a ring gyroscope and its dynamic model, this invention gives the variation law of the zero rate in two working modes before and after the inversion of the driving mode and the detection mode, and controls the ring gyroscope to switch between the two working modes through a signal processing circuit. By taking the difference between the detection signals in two adjacent working modes, the zero-rate online self-calibration of the MEMS ring gyroscope is finally realized, solving the technical problems of relatively poor zero-rate repeatability and high calibration cost of existing MEMS gyroscopes. However, its technical solution does not solve the technical problems of the complex self-calibration method of MEMS inertial sensors and the inability to monitor the high-resolution motion state of a MEMS inertial vibration platform. Summary of the Invention

[0007] The technical problem to be solved by this invention: Currently, MEMS inertial sensors have the technical problem of difficult self-calibration. A MEMS inertial vibration system with a self-measuring function of motion attitude and its preparation method are proposed, which can self-monitor the motion state of a MEMS inertial vibration platform, provide a reference for the self-calibration of MEMS inertial sensors, and simplify the self-calibration implementation method.

[0008] To solve the above technical problems, this invention adopts the following technical solutions: A MEMS inertial vibration system with a self-measuring function of motion attitude, used to provide a reference for the self-calibration of MEMS inertial sensors, includes:

[0009] An inertial vibration platform that moves with multi-directional degrees of freedom, and the direction conforms to the cooperative bending vibration generated by the inertial vibration platform under a voltage excitation signal;

[0010] A PMUT array, which is arrayed on the bottom surface of the inertial vibration platform at a preset interval and is bonded to the bottom surface of the inertial vibration platform. The PMUT array includes a plurality of transmitting sub-arrays and a plurality of receiving sub-arrays. The transmitting sub-arrays and the receiving sub-arrays correspond one by one. Each of the transmitting sub-arrays and the receiving sub-arrays includes a plurality of PMUT single tubes, and the plurality of PMUT single tubes are connected to each other to form a transmitting sub-array or a receiving sub-array.

[0011] Preferably, the inertial vibration platform includes a substrate I, a lower electrode layer, a piezoelectric layer I, an upper electrode layer, an isolation layer, a top trace layer, a central table and four folding beams. A cavity structure required for the movement of the inertial vibration platform is provided on the back of the substrate I. The central table and the four folding beams are both arranged in the substrate I. The central table is fixedly installed in the middle of the substrate I. The folding beams are symmetrically distributed. One side of the folding beam is connected to the four side surfaces of the central table, and the other side is connected to the substrate I. The substrate I is successively provided with a lower electrode layer, a piezoelectric layer I, an upper electrode layer, an isolation layer and a top trace layer. The top trace layer is processed to form an excitation trace connected to the upper electrode layer and a communication trace of the MEMS inertial sensor.

[0012] Preferably, the upper electrode layer is processed to form four partition driving electrodes. The four partition driving electrodes are respectively located on the four folding beams. The isolation layer is provided with a plurality of through holes I at the positions of the partition driving electrodes. The excitation trace is connected to the partition driving electrodes of the upper electrode layer through the through holes I.

[0013] Preferably, the PMUT single tube includes a substrate II, a bottom electrode layer, a piezoelectric layer II and a top electrode layer. The bottom electrode layer, the piezoelectric layer II and the top electrode layer are successively arranged on the substrate II.

[0014] Preferably, the PMUT single tube includes a seed layer. The seed layer is located between the substrate II and the bottom electrode layer, and the material of the seed layer is the same as that of the piezoelectric layer II.

[0015] Preferably, the substrate II includes a top silicon layer, a buried oxide layer and a bottom silicon layer. The buried oxide layer and the top silicon layer are successively arranged on the bottom silicon layer. The PMUT single tube is a circular diaphragm structure, and a circular hole type vibration cavity is provided on the bottom silicon layer.

[0016] Preferably, the piezoelectric layer II is circular and its diameter is equal to the diameter of the vibration cavity. The top electrode layer is circular and its diameter is smaller than the diameter of the vibration cavity.

[0017] Preferably, a plurality of through holes II are provided on the PMUT single tube. The plurality of through holes II are arranged on the ring formed by the top electrode layer and the piezoelectric layer II and are located between the top electrode layer and the bottom silicon layer.

[0018] Preferably, a plurality of damping grooves are provided on the inertial vibration platform for releasing the squeeze film damping generated during vertical movement and the sliding film damping generated during horizontal movement.

[0019] A preparation method of a MEMS inertial vibration system with a motion attitude self-test function as described above includes the following steps:

[0020] Deposit and form the lower electrode layer of the inertial vibration platform on Substrate I;

[0021] Deposit and form Piezoelectric Layer I of the inertial vibration platform on the lower electrode layer;

[0022] Deposit and form the upper electrode layer of the inertial vibration platform on Piezoelectric Layer I, and etch the upper electrode layer to form four partition drive electrodes;

[0023] Grow a layer of silicon dioxide at room temperature on the upper electrode layer as an isolation layer, and open a number of via holes I at the positions of the partition drive electrodes in the isolation layer;

[0024] Deposit and form the top trace layer of the inertial vibration platform on the isolation layer, and etch the top trace layer to form the excitation trace and the communication trace of the MEMS inertial sensor, and the excitation trace is connected to the upper electrode layer through via hole I;

[0025] Etch on the back of Substrate I to form the cavity structure required for the movement of the inertial vibration platform, and etch from the front of Substrate I to the bottom to form the inertial vibration platform structure;

[0026] Deposit and form the bottom electrode layer of the PMUT single tube on Substrate II;

[0027] Deposit and form Piezoelectric Layer II of the PMUT single tube on the bottom electrode layer;

[0028] Deposit and form the top electrode layer of the PMUT single tube on Piezoelectric Layer II;

[0029] Etch from the front of Piezoelectric Layer II to the buried oxide layer to form via hole II;

[0030] Etch the bottom silicon layer to form the circular hole type vibration cavity of the PMUT single tube;

[0031] Connect a number of the PMUT single tubes to form a PMUT array;

[0032] Align and bond the bottom surface of the prepared inertial vibration platform with the front surface of the prepared PMUT array.

[0033] The beneficial technical effects of the present invention include: adopting a MEMS inertial vibration system with a self-measuring function of motion posture and a preparation method, obtaining the distance data between the PMUT array and the inertial vibration platform through the non-contact detection method of the PMUT array, realizing the self-monitoring of the high-resolution motion state of the MEMS inertial vibration platform, without the need to set up an additional corresponding detection module for the inertial vibration platform, nor causing damage to the main structure of the inertial vibration platform. Moreover, the self-monitoring of the motion state of the inertial vibration platform by the PMUT array provides a motion reference for the closed-loop self-calibration of the MEMS inertial sensor, simplifying the self-calibration implementation method of the MEMS inertial sensor; through the reasonable design of the damping groove, the energy loss caused by air damping is greatly reduced, which is beneficial for the inertial vibration platform to obtain better output capabilities.

[0034] Other features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the drawings:

[0036] Figure 1 It is a schematic structural diagram of the MEMS inertial vibration system according to an embodiment of the present invention;

[0037] Figure 2 It is a schematic structural diagram of the inertial vibration platform according to an embodiment of the present invention;

[0038] Figure 3 It is a schematic bottom view structural diagram of the inertial vibration platform according to an embodiment of the present invention;

[0039] Figure 4 It is a schematic structural diagram of the upper electrode layer of the inertial vibration platform according to an embodiment of the present invention;

[0040] Figure 5 It is a schematic structural diagram of a single PMUT tube according to an embodiment of the present invention;

[0041] Figure 6 It is a schematic diagram of the ultrasonic signal propagation path according to an embodiment of the present invention;

[0042] Figure 7 It is a flowchart of the preparation method of the MEMS inertial vibration system according to an embodiment of the present invention.

[0043] Among them: 1. Inertial vibration platform; 2. PMUT array; 3. Transmitting sub-array; 4. Receiving sub-array; 5. Single PMUT tube; 6. Substrate I; 7. Lower electrode layer; 8. Piezoelectric layer I; 9. Partition driving electrode; 10. Isolation layer; 11. Excitation trace; 12. Communication trace; 13. Central tabletop; 14. Folded beam; 15. Cavity structure; 16. Damping groove; 17. Substrate II; 18. Top silicon layer; 19. Buried oxide layer; 20. Bottom silicon layer; 21. Seed layer; 22. Bottom electrode layer; 23. Piezoelectric layer II; 24. Top electrode layer; 25. Circular hole type vibration cavity; 26. Via II. Specific implementation manner

[0044] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings of the embodiments of the present invention. However, the following embodiments are only the preferred embodiments of the present invention, not all of them. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without creative efforts all fall within the protection scope of the present invention.

[0045] In the following description, terms such as "inner", "outer", "upper", "lower", "left", "right", etc. indicating directions or positional relationships are only for convenience of describing the embodiments and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be construed as a limitation to the present invention.

[0046] Before introducing the technical solutions of this embodiment, the background of the application of this embodiment will be introduced first. MEMS, that is, microelectromechanical systems, integrates micro sensors, actuators, signal processing and control circuits, interface circuits, communication and power supplies, and has developed with the development of semiconductor integrated circuit microfabrication technology and ultra-precision machining technology. MEMS inertial sensors mainly include MEMS gyroscopes, MEMS accelerometers, MEMS magnetometers, and MEMS-IMUs, etc.

[0047] MEMS inertial sensors have significant advantages over traditional inertial sensors in terms of volume, power consumption, cost, etc. In particular, their feature of being mass-produced using semiconductor processes can greatly reduce volume and cost. For example, before the application of MEMS inertial sensors, it was very difficult to achieve the now-popular consumer-grade quadcopter because attitude control in it had to use corresponding inertial sensors. Traditional inertial sensors, especially gyroscopes, were limited by their implementation principles, being large in volume and high in cost, and thus difficult to apply in consumer-grade products. However, after the successful commercialization of MEMS inertial sensors, such consumer-grade aircraft have flourished. In addition to consumer-grade quadcopter drones, such highly integrated MEMS inertial sensors can provide us with sufficient motion information and can be applied to functions such as somatosensory detection and camera anti-shake. As for an important application of future development of consumer-grade MEMS inertial sensors, it is to provide inertial navigation when there is no satellite signal, such as indoors or underground.

[0048] A MEMS inertial vibration system with a self-measuring function of motion attitude is used to provide a reference for the self-calibration of MEMS inertial sensors. Please refer to the appendix Figure 1 , including:

[0049] An inertial vibration platform 1 that moves with multi-directional degrees of freedom, and the direction is consistent with the cooperative bending vibration generated when the inertial vibration platform 1 receives a voltage excitation signal;

[0050] A PMUT array 2 is distributed in an array at a preset interval on the bottom surface of the inertial vibration platform 1 and is bonded to the bottom surface of the inertial vibration platform 1. The PMUT array 2 includes a number of transmitting sub-arrays 3 and a number of receiving sub-arrays 4. The transmitting sub-arrays 3 and the receiving sub-arrays 4 correspond one by one. Each of the transmitting sub-arrays 3 and the receiving sub-arrays 4 includes a number of PMUT single tubes 5. The number of PMUT single tubes 5 are connected to each other to form the transmitting sub-array 3 or the receiving sub-array 4, which is used to obtain information on the multi-degree-of-freedom motion attitude of the upper inertial vibration platform 1. Among them, the PMUT array 2 also includes a timer.

[0051] By using the non-contact detection method of the PMUT array 2, distance data between the PMUT array 2 and the inertial vibration platform 1 is obtained, realizing the self-measurement of the high-resolution motion attitude of the inertial vibration platform 1. This not only simplifies the motion attitude monitoring method of the inertial vibration platform 1 without setting additional corresponding detection modules for the inertial vibration platform 1, but also does not damage the main structure of the inertial vibration platform 1. At the same time, the self-measurement of the motion attitude of the inertial vibration platform 1 by the PMUT array 2 provides a motion reference for the closed-loop self-calibration of MEMS inertial sensors, simplifying the self-calibration implementation method of MEMS inertial sensors.

[0052] Please refer to the appendix Figure 2and appendix Figure 3 As shown in Figure 3 , the inertial vibration platform 1 includes a substrate I 6, a lower electrode layer 7, a piezoelectric layer I 8, an upper electrode layer, an isolation layer 10, a top trace layer, a central table 13, and four folding beams 14. A cavity structure 15 required for the movement of the inertial vibration platform 1 is provided on the back of the substrate I 6. The central table 13 and the four folding beams 14 are both arranged in the substrate I 6. The central table 13 is fixedly installed in the middle of the substrate I 6. The folding beams 14 are symmetrically distributed. One side of the folding beam 14 is connected to the four side surfaces of the central table 13, and the other side is connected to the substrate I 6, so that the folding beam 14 serves as the support structure of the central table 13 and the elastic structure for realizing the multi-degree-of-freedom movement generated by the vibration of the inertial vibration platform 1. The lower electrode layer 7, the piezoelectric layer I 8, the upper electrode layer, the isolation layer 10, and the top trace layer are sequentially provided on the substrate I 6. The isolation layer 10 is used to isolate the electrical interference from the upper electrode layer and the top trace layer. The top trace layer is processed to form an excitation trace 11 connected to the upper electrode layer and a communication trace 12 of the MEMS inertial sensor.

[0053] Please refer to the appendix Figure 4 As shown in Figure 4 , the upper electrode layer is processed to form four partition drive electrodes 9. The four partition drive electrodes 9 are respectively located on the four folding beams 14. The isolation layer 10 is provided with a plurality of through holes I at the positions of the partition drive electrodes 9. The excitation trace 11 is connected to the partition drive electrodes 9 of the upper electrode layer through the through holes I.

[0054] Please refer to the appendix Figure 5 As shown in Figure 5 , the PMUT single tube 5 includes a substrate II 17, a bottom electrode layer 22, a piezoelectric layer II 23, and a top electrode layer 24. The bottom electrode layer 22, the piezoelectric layer II 23, and the top electrode layer 24 are sequentially provided on the substrate II 17.

[0055] Among them, the PMUT single tube 5 includes a seed layer 21. The seed layer 21 is located between the substrate II 17 and the bottom electrode layer 22. The material of the seed layer 21 is the same as that of the piezoelectric layer II 23, so as to ensure the effective deposition of the piezoelectric layer II 23.

[0056] Among them, the substrate II 17 includes a top silicon layer 18, a buried oxide layer 19, and a bottom silicon layer 20. The buried oxide layer 19 and the top silicon layer 18 are sequentially provided on the bottom silicon layer 20. The PMUT single tube 5 is a circular diaphragm structure, and a circular hole type vibration cavity 25 is provided on the bottom silicon layer 20.

[0057] Among them, the piezoelectric layer II 23 is circular and its diameter is equal to the diameter of the vibration cavity. The top electrode layer 24 is circular and its diameter is smaller than the diameter of the vibration cavity. A plurality of through holes II 26 are provided on the PMUT single tube 5, and the plurality of through holes II 26 are arranged on the ring formed by the top electrode layer 24 and the piezoelectric layer II 23 and are located between the top electrode layer 24 and the bottom silicon layer 20. The plurality of through holes II 26 are symmetrically distributed, which can not only release the residual stress in the manufacturing process of the PMUT single tube 5, but also achieve the effect of adjusting the stiffness of the PMUT single tube 5, thereby improving the transmission sensitivity of the PMUT array 2.

[0058] Among them, a plurality of damping grooves 16 for releasing the squeeze film damping generated during vertical movement and the sliding film damping generated during horizontal movement are provided on the inertial vibration platform 1. Through the reasonable design of the damping grooves 16, the energy loss caused by air damping to the inertial vibration platform 1 can be minimized to the greatest extent when the characteristic frequency and vibration amplitude of the inertial vibration platform 1 are very small, which is beneficial to the inertial vibration platform 1 obtaining better output capabilities.

[0059] This embodiment provides an implementation manner of a MEMS inertial vibration system with a self-measurement function of the motion attitude: The inertial vibration platform 1 utilizes the inverse piezoelectric effect of the piezoelectric layer I 8. When it receives an accurate voltage excitation signal to generate an electric field, the piezoelectric layer I 8 generates strain, causing the four folded beams 14 on the side of the central table 13 to generate cooperative bending vibrations, thereby driving the multi-degree-of-freedom mechanical motion of the central table 13.

[0060] According to the finite element simulation results, the structure of the inertial vibration platform 1 can have a six-degree-of-freedom motion mode, with a total of four order modes. The first order mode is the out-of-plane vibration of the central table 13 along the z-axis direction, the second order mode is the tilt of the central table 13 along the x-axis or y-axis, the third order mode is the in-plane translation motion of the central table 13 along the x-axis or y-axis, and the fourth order mode is the in-plane rotation of the central table 13 around the geometric center. Taking the first order mode as an example, sinusoidal voltage signals with the same amplitude and opposite phases are applied to the four partition driving electrodes 9 respectively, so that the four folded beams 14 are subjected to driving forces in the same direction, realizing the out-of-plane vibration of the inertial vibration platform 1 along the z-axis direction. According to the relationship between the applied sinusoidal voltage signal and the vibration displacement of the inertial vibration platform 1, the standard inertial quantity output by the inertial vibration platform 1 is obtained.

[0061] Please refer to the appendix Figure 6 , the PMUT array 2 utilizes the ultrasonic waves generated during the high-frequency vibration of the piezoelectric layer II 23, and calculates the distance data from the inertial vibration platform 1 above through the ultrasonic flight time, thereby realizing the accurate self-measurement of the motion attitude of the inertial vibration platform 1.

[0062] Specifically, the PMUT transmitting sub-array 3 transmits ultrasonic signals at a certain frequency. After the ultrasonic signals encounter the inertial vibration platform 1 located above, they are reflected to the PMUT receiving sub-array 4. The PMUT receiving sub-array 4 receives the ultrasonic signals, and the ultrasonic flight time Δt is obtained by timing with a timer. Using the formula the distance data between the PMUT array 2 and the inertial vibration platform 1 above can be obtained at this time, where c is the speed of sound and L is the distance from the PMUT transmitting array end to the PMUT receiving array end.

[0063] Subsequently, the calculated distance data between the PMUT array 2 and the inertial vibration platform 1 above is compared with the standard inertial quantity output by the inertial vibration platform 1, so as to realize the closed-loop self-calibration of the MEMS inertial sensor and solve the long-term stability problem faced by the MEMS inertial sensor.

[0064] A preparation method of a MEMS inertial vibration system with a motion attitude self-test function as described above, please refer to the appendix Figure 7 , including the following steps:

[0065] Step A01) Deposit and form the lower electrode layer 7 of the inertial vibration platform 1 on the substrate Ⅰ6;

[0066] Step A02) Deposit and form the piezoelectric layer Ⅰ8 of the inertial vibration platform 1 on the lower electrode layer 7;

[0067] Step A03) Deposit and form the upper electrode layer of the inertial vibration platform 1 on the piezoelectric layer Ⅰ8, and etch the upper electrode layer to form four partition driving electrodes 9;

[0068] Step A04) Grow a layer of silicon dioxide at room temperature on the upper electrode layer as the isolation layer 10, and the isolation layer 10 opens several through holes Ⅰ at the positions of the partition driving electrodes 9;

[0069] Step A05) Deposit and form the top trace layer of the inertial vibration platform 1 on the isolation layer 10, and etch the top trace layer to form the excitation trace 11 and the communication trace 12 of the MEMS inertial sensor. The excitation trace 11 is connected to the upper electrode layer through the through hole Ⅰ;

[0070] Step A06) Etch the back of the substrate Ⅰ6 to form the cavity structure 15 required for the movement of the inertial vibration platform 1, and etch from the front of the substrate Ⅰ6 to the bottom surface to form the inertial vibration platform 1 structure;

[0071] Step A07) Deposit and form the bottom electrode layer 22 of the PMUT single tube 5 on the substrate Ⅱ17;

[0072] Step A08) Deposit and form the piezoelectric layer Ⅱ23 of the PMUT single tube 5 on the bottom electrode layer 22;

[0073] Step A09): Deposit and form the top electrode layer 24 of the PMUT single tube 5 on the piezoelectric layer II 23;

[0074] Step A10): Etch from the front surface of the piezoelectric layer II 23 to the buried oxide layer 19 to form the via hole II 26;

[0075] Step A11): Etch the bottom silicon layer 20 to form the circular hole type vibration cavity 25 of the PMUT single tube 5;

[0076] Step A12): Connect a plurality of PMUT single tubes 5 to each other to form the PMUT array 2;

[0077] Step A13): Align and bond the bottom surface of the prepared inertial vibration platform 1 with the front surface of the prepared PMUT array 2.

[0078] As described above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the content described in the drawings and the above specific implementation manner. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. A MEMS inertial vibration system with a self-measuring function of motion posture, which is used to provide a reference for the self-calibration of MEMS inertial sensors, is characterized in that Comprising: An inertial vibration platform that moves with multi-directional degrees of freedom, where the directions are consistent with the cooperative bending vibrations generated by the inertial vibration platform when receiving a voltage excitation signal; A PMUT array that is arrayed at a preset interval on the bottom surface of the inertial vibration platform and bonded to the bottom surface of the inertial vibration platform. The PMUT array includes a number of transmitting sub-arrays and a number of receiving sub-arrays, with the transmitting sub-arrays and receiving sub-arrays corresponding one by one. Each of the transmitting sub-arrays and receiving sub-arrays includes a number of PMUT single tubes, and the number of said PMUT single tubes are interconnected to form a transmitting sub-array or a receiving sub-array.

2. A MEMS inertial vibration system with a self-measuring function of motion posture according to claim 1, characterized in that The inertial vibration platform includes a substrate I, a lower electrode layer, a piezoelectric layer I, an upper electrode layer, an isolation layer, a top wiring layer, a central table, and four folding beams. A cavity structure required for the movement of the inertial vibration platform is provided on the back surface of the substrate I. The central table and the four folding beams are both arranged in the substrate I. The central table is fixedly installed in the middle of the substrate I. The folding beams are symmetrically distributed. One side of the folding beam is connected to the four side surfaces of the central table, and the other side is connected to the substrate I. The lower electrode layer, the piezoelectric layer I, the upper electrode layer, the isolation layer, and the top wiring layer are sequentially provided on the substrate I. The top wiring layer is processed to form an excitation wiring connected to the upper electrode layer and a communication wiring of the MEMS inertial sensor.

3. A MEMS inertial vibration system with a self-measuring function of motion posture according to claim 2, characterized in that Four partition driving electrodes are processed on the upper electrode layer. The four partition driving electrodes are respectively located on the four folding beams. A number of through holes I are provided in the isolation layer at the positions of the partition driving electrodes. The excitation wiring is connected to the partition driving electrodes of the upper electrode layer through the through holes I.

4. A MEMS inertial vibration system with a self-measuring function of motion posture according to claim 1, characterized in that The PMUT single tube includes a substrate II, a bottom electrode layer, a piezoelectric layer II, and a top electrode layer. The bottom electrode layer, the piezoelectric layer II, and the top electrode layer are sequentially provided on the substrate II.

5. A MEMS inertial vibration system with a self-measuring function of motion posture according to claim 4, characterized in that The PMUT single tube includes a seed layer, and the seed layer is located between the substrate II and the bottom electrode layer. The material of the seed layer is the same as that of the piezoelectric layer II.

6. A MEMS inertial vibration system with a self-measuring function of motion posture according to claim 5, characterized in that The substrate II includes a top silicon layer, a buried oxide layer, and a bottom silicon layer. The buried oxide layer and the top silicon layer are sequentially provided on the bottom silicon layer. The PMUT single tube is a circular diaphragm structure, and a circular hole type vibration cavity is provided on the bottom silicon layer.

7. A MEMS inertial vibration system with a self-measuring function of motion posture according to claim 6, characterized in that The piezoelectric layer II is circular and has a diameter equal to that of the vibration cavity. The top electrode layer is circular and has a diameter smaller than that of the vibration cavity.

8. A MEMS inertial vibration system with a self-test function for motion posture, characterized in that a plurality of through holes II are provided on the single PMUT tube, and the plurality of through holes II are arranged on a ring formed by the top electrode layer and the piezoelectric layer II and are located between the top electrode layer and the bottom silicon layer.

9. A MEMS inertial vibration system with a self-test function for motion posture according to claim 1, characterized in that a plurality of damping grooves are provided on the inertial vibration platform for releasing the squeeze film damping generated during vertical movement and the sliding film damping generated during horizontal movement.

10. The preparation method of a MEMS inertial vibration system with a self-test function for motion posture according to any one of claims 1 to 9, characterized in that, It includes the following steps: Depositing and forming the lower electrode layer of the inertial vibration platform on the substrate I; Depositing and forming the piezoelectric layer I of the inertial vibration platform on the lower electrode layer; Depositing and forming the upper electrode layer of the inertial vibration platform on the piezoelectric layer I, and etching the upper electrode layer to form four partition drive electrodes; Growing a layer of silicon dioxide at room temperature on the upper electrode layer as an isolation layer, and opening a plurality of through holes I at the positions of the partition drive electrodes on the isolation layer; Depositing and forming the top trace layer of the inertial vibration platform on the isolation layer, and etching the top trace layer to form the excitation trace and the communication trace of the MEMS inertial sensor, and the excitation trace is connected to the upper electrode layer through the through hole I; Etching the back surface of the substrate I to form a cavity structure required for the movement of the inertial vibration platform, and etching from the front surface of the substrate I to the bottom surface to form the inertial vibration platform structure; Depositing and forming the bottom electrode layer of the single PMUT tube on the substrate II; Depositing and forming the piezoelectric layer II of the single PMUT tube on the bottom electrode layer; Depositing and forming the top electrode layer of the single PMUT tube on the piezoelectric layer II; Etching from the front surface of the piezoelectric layer II to the buried oxide layer to form the through hole II; Etching the bottom silicon layer to form a circular hole type vibration cavity of the single PMUT tube; Connecting a plurality of the single PMUT tubes to form a PMUT array; Aligning and bonding the bottom surface of the prepared inertial vibration platform with the front surface of the prepared PMUT array.

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