Research On MEMS Biaxial High G Piezoresistive Accelerometer

Accelerometer is an important inertial device for measuring acceleration time course change,which has a significant contribution to the development of industrial manufacturing,information communication and defense military.The focal point of this paper is to address the need for detecting multidimensional high g-value acceleration signals in space,such as weapons intrusion,explosive impact,and aerospace satellites.To meet this demand,a high g-value biaxial piezoresistive accelerometer has been designed with a tension-compression measurement mechanism.The sensor processing process and packaging scheme have also been analyzed.This paper’s research work:(1)The semiconductor materials for producing piezoresistive sensor were choosed,and the application of piezoresistive effect and anisotropic piezoresistance coefficients was analyzed.The performance targets of the designed sensor were determined based on the application requirements of high-g accelerometer.The measurement mechanism of piezoresistive sensors was analyzed,and a sensitive structure for a high-g biaxial acceleration sensor with tension-compression measurement mechanism was designed,and the shape and arrangement of piezoresistive elements were determined.(2)By combining topological analysis with actual processing,the preliminary design of the structure has been optimized,leading to a 9.85% increase in the first natural frequency.Furthermore,using parameter sensitivity analysis and response surface multi-objective optimization methods,the sensor size parameters have been optimized,resulting in a 9.2%increase in maximum equivalent stress and a 9.9% increase in the first natural frequency.By studying the stress distribution characteristics of the constructed model under acceleration in different directions,an acceleration measurement circuit resistant to cross-interference was designed,effectively reducing cross-interference.Additionally,a backend amplification circuit was configured.(3)Finite element simulation analysis was conducted on a high-g biaxial accelerometer to obtain the range and overload capacity through static analysis,the response process through transient dynamics,the mode of vibration through modal analysis,and the resonance frequency of the structure was verified through harmonic response analysis.Finally,a relationship model was established between the output voltage of the sensor and the acceleration,completing the sensitivity analysis.The results show that the full range of the sensor is 200000 g,and it can withstand up to three times its own load.The X-axis sensitivity is 1.39 μV/g with a resonance frequency of 509.8 k Hz,while the Y-axis sensitivity is 1.42μV/g with a resonance frequency of 510.2 k Hz.(4)The process and package flow of the high g-value biaxial accelerometer were studied by combining the characteristics of the structure of the sensor and the requirements of the process.The key process steps in the sensor process flow,including thin film deposition,doping,etching,and bonding,were analyzed.The key process parameters of each step were determined,and the packaging scheme of the high-g biaxial accelerometer was completed.