Research On High Temperature And High Impact Of Piezoelectric Thin Film Of MEMS Accelerometer

Micro-accelerometer has many wide applications in various fields of human production and life.Piezoelectric accelerometer represented by piezoelectric thin film accelerometer has the characteristics of miniaturization,long-life,low-cost,simple structure and wide measuring range,which becomes the mainstream of Engineering research.Especially,it has an important academic significance and application value in the high temperature,high impact and other harsh environmental measurement.In the paper,based on the application requirement of special environmental monitoring,aiming at the application requirement of high temperature and high impact resistance,a micro piezoelectric accelerometer based on AlN piezoelectric thin film is set up as a research object.Establishing the equivalent physical model of piezoelectric thin film accelerometer.Carrying out The theoretical research of four cantilever beammass block structure and disk-mass block structure.Designing the sensitive structure of a disc-type piezoelectric thin film accelerometer.Using Comsol simulation program analyzes the vibration mode,dynamic response,impact response,stress-strain and high temperature stress characteristics of the sensitive structure.Forming the process flow with AlN piezoelectric thin film as the core preparation technology.Completing the process of manufacturing the sensor sensitive structure by the MEMS process.Carrying out the material characterization,LDV test,shaking table test and impact acceleration test of the device,and analyzing and evaluating the performance of the device.The main works of this paper is as follows.(1)Aiming at the application requirements of high temperature,high impact and strong magnetic environment,the research progress and development direction of four main types of micro-electro-mechanical accelerometers are summarized,and the technical scheme of micro-electro-mechanical piezoelectric film accelerometer is determined to meet the research needs.(2)Based on the application requirements of high temperature resistance and process compatibility,AlN piezoelectric thin films are selected as high temperature functional thin films.Based on the characteristics of impact resistance and miniaturization,proposing a four-cantilever beam-center mass block structure and a disk-center mass block structure.(3)Based on the proposed two structures and lumped parameter models,deriving the moment equation,deflection equation,vibration displacement equation,natural frequency equation,motion equation and dynamic response equation of the equivalent system.Using piezoelectric equation of AlN thin film,the output of excitation response is solved and the mechanical-electrical model is established.(4)Using Comsol finite element simulation,analyzing the vibration modes,dynamic response,impact response,stress-strain,high temperature stress and other characteristics of the two structures,and obtaining the output performance and sensitivity.(5)Based on the requirement of high temperature resistance and impact resistance,considering the process difficulty and performance index,the processing scheme of disc-center mass block structure is determined,the processing of sensitive structure is completed,and the processing steps and process parameters are discussed.Based on the existing sensitive structure chips,the characterization of size parameters,material parameters and basic electrical parameters is carried out,and the properties of materials are studied.(6)Studying The performance test and analysis methods of high temperature and high impact accelerometer.Carrying out LDV test,shaking table test,small impact table test,high temperature and shock resistance test.Verifying the design and theoretical indicators,and analyzing the test results and the causes of the problems.