Research On Structure Optimization And Fabrication Process Of Piezoelectric Ring MEMS Gyroscope

With the guidance of conventional weapons and the miniaturization of guided weapons,the development of MEMS gyroscope with strong shock resistance,high dynamic range and small volume is of great significance.In this paper,a piezoelectric ring MEMS gyroscope is designed and manufactured,using Al N piezoelectric film attached to the surface of silicon-based ring structure as transducer,which can drive and detect the gyroscope based on piezoelectric effect.Compared with capacitive MEMS gyroscope,it has the characteristics of simple structure and strong shock resistance.This paper mainly focuses on the optimation of the resonant structure and processing technology of the piezoelectric ring MEMS gyroscope.The main research work is as follows:1.The principle of piezoelectric driving and detection is analyzed based on the the constitutive equations of piezoelectric effect,and the bending piezoelectric actuator and sensor model are established;The simulation of piezoelectric thin film gyroscope are completed based on COMSOL to verify the driving and detecting principle of piezoelectric thin film.2.The influence of gyro structure parameters on performance parameters is studied by finite element method;A method to improve the performance parameters of gyro based on the thermal isolation slots is proposed,and the parameters of the resonant strucutre and the thermal isolation slots are optimized,and the gyro resonant structure with improved performance parameters is obtained.3.Considering the material properties and fabrication process,Al N is selected as the piezoelectric film to design the fabrication process of gyro sensitive structure,the gyro sensitive structure is manufactured.The influence of different patch methods on the thermal stress of gyro structure is studied by finite element simulation,a low stress patch method is used;Then the gyro sensitive structure is vacuum encapsulated to obtain gyro principal prototype,besides,the effect of vacuum encapsulation is tested.4.The encapsulated gyro principal prototype is equipped with measurement and control circuit,the force balance control system of the gyro is built based on the phase-locked amplifier,and the performance of the gyro is tested.The test results show that the gyro can achieve the expected function,the bias stability of the gyro is 103 °/h.