Design And Process Study Of Triaxial MEMS Micro Accelerometer Based On SOI

MEMS micro-accelerometers are widely used in inertial navigation,guidance,automotive airbag deployment and motion control systems.Capacitive MEMS accelerometers based on capacitive sensing have the advantages of lower temperature coefficient,lower power consumption,lower manufacturing cost,and integration with traditional integrated circuits.The SOI silicon wafer has good single crystal characteristics,it is easy to process a device with a large thickness,it is easy to process a structure with a high aspect ratio,the mechanical stability of the device is good,the residual stress of the manufactured device is relatively small,and the follow-up of the device The advantages of simpler process are generally favored in various sensor fields.Combining the research background and current situation,this thesis takes the threeaxis MEMS micro-accelerometer based on SOI as the research object,and has successively researched the structure design,model establishment,simulation analysis and processing technology of the micro-accelerometer.The specific research is as follows:First,it introduces MEMS technology,then introduces the advantages of SOI technology and SOI technology in the field of micro-accelerometer.Afterwards,we compare different micro-accelerometers based on different sensing principles.Secondly,a brief introduction to the research and development status of micro-accelerometers with different sensing principles at home and abroad.Finally,it explains the reason why this article chooses the subject of three-axis MEMS micro-accelerometer based on SOI as the research object,and explains the research significance of choosing this research object in this paper.Then the basic principle of the micro-accelerometer is analyzed,the parallel plate capacitor model corresponding to the capacitive micro-accelerometer with differential capacitance is analyzed,the structure of the elastic beam of the micro-accelerometer and the structure of the comb-tooth capacitor are studied.After comparative analysis,the snake is selected The shape beam is used as the elastic beam,and the constant-height comb-tooth structure with fixed-tooth offset structure and the unequal-height comb-tooth structure with fixed-tooth arrangement structure are selected as the capacitance detection structure.Based on the above theory,a three-axis MEMS micro-accelerometer structure with increased mass is designed.After that,the finite element analysis method and the simulation software ANSYS Workbench 19.1 with graphical interface used in this paper are briefly introduced.The structural parameters of the micro-accelerometer were optimized using ANSYS Workbench 19.1 software.The structural statics simulation of the micro-accelerometer designed in this paper was done,and the linearity analysis proved that the linearity was good in the range of 0g-1000 g,and the range of the micro-accelerometer was 1000 g.The structural dynamics simulation of the designed micro-accelerometer was performed,and it was found that the resonance frequencies between the X,Y,and Z axes are quite different,that is,the cross-axis interference of the X,Y,and Z axes of the designed micro accelerometer is relatively small.,The same as the design goal.Finally,a simulation comparison of the folded beam and serpentine beam structures of the microaccelerometer is made.Finally,the entire technological process of the micro-accelerometer structure is designed.The important process steps were studied under the existing laboratory conditions,and reasonable process parameters required for most processes were obtained.MEMS micro-accelerometers are widely used in inertial navigation,guidance,automotive airbag deployment and motion control systems.Capacitive MEMS accelerometers have the advantages of low temperature coefficient,low power consumption,low manufacturing cost,and integration with integrated circuits.They have been widely used and highly concerned in the MEMS market.SOI(silicon-on insulator,silicon-on-insulator)silicon wafer with its superior single crystal material characteristics,easy to realize large thickness devices,easy to achieve high aspect ratio manufacturing,good mechanical stability,small residual stress and simple subsequent manufacturing process The advantages are gradually widely used in the field of micro-accelerometers,which is an important development direction of inertial sensing technology in the future.