Silicon Micro-resonator Accelerometer Structure Design Technology Research

Silicon MEMS resonant accelerometer,with a quasi-digital output which has high presicion and strong anti-jamming capability,has become one of the hotest research topic. This thesis presents the research on the structure design of micromechanical silicon oscillating accelerometer,and the details are as follows:1) Design and analysis of DETF resonantThe theoretical derivation and simulation analysis of DETF resonator are carried out. Mainly consists of the DETF resonator theoretical derivation and simulation analysis. Theoretical part includes:Establishing theoretical models of the resonant frequencies of the beam,the resonant frequency with the affect of axial forces and nonlinear vibration of the resonator.The theoretical models are tested by FEA simulation.The electrical model are analyzed in details,including the driving method.And the equivalent electrical model is derived.Besides,modal analysis of DETF resonator and electrostatic driving simulation are carried out.2) Design and analysis of micro leverUnder the consideration of the processing condition,micro lever is analysis,designed and optimized.The micro lever consist of four parts,including pivot,input,output and connection of leverage and resonator.According to the principle of force-equilibrium and moment-equilibrium,amplification factor of the micro lever is analyzed and derived.The influence on the performance of the micro lever are analyzed by simulation.3) Design and simulation of the whole structureThe key performance parameters of the accelerometer including scale factor,linearity, range,noise and bandwidth are analyzed.According to the design requirements and the processing conditions,the whole structure is designed.The structure is simulated by ANSYS and Matlab,etc.The designed accelerometer has a normal frequency of 29kHz,a scale factor of 95Hz/g,a bandwith of 3624.5Hz,a measuring range of±50g and its differential output frequency has good linearity,with correlation coefficient of 0.099%,a resolution of 0.087mg.4) Processing error analysisAnalysis of errors coming from the processing,mainly including:mismatch of the size of DETF,mismatch of the thickness,mismatch of the distance between combs,mismatch of the elastic system.According to the analysis,in addition to improving the processing technic,elastic system and resonant beam must be best chosen to reduce the errors coming from the processing and increase the performance of accelerometers.