Design and Experiment of a Hybrid-Integrated Ultrahigh-g Accelerometer With Variable-Section Beam

Abstract

Due to the special fields of aerospace, explosion impact, weapon penetration and other high g value acceleration test, the sensor test range and anti-overload capability have great requirements. At present, most accelerometer beams with equal section are used. The existing data prove that the beam structure with variable section can effectively solve the problem of stress concentration, improve the anti-overload capability of acceleration sensor, and increase the system stability through theoretical simulation. This study presents a hybrid-integrated high-precision MEMS ultra-high-g piezoresistive accelerometer, which is composed of a sensitive structure and an ASIC interface (application specific integrated circuit). Based on the traditional constant-section four-beam accelerometer, a variable-section beam is proposed, and the section size increases linearly with the length of beam. Through finite element simulation analysis, it is verified that the variable section beam has the characteristics of reducing stress concentration and can improve the anti-overload ability of the accelerometer. The simulation results show that the maximum stress of the structure under 200,000 g is 28.34 MPa, and its resonance frequency is 548 kHz. Finally, the processing flow is designed, and the fabrication of MEMS chip is completed. Based on the TSMC 0.35 μm process, the ASIC interface is designed and fabricated to process the signal from the sensing element and realize the functions of amplification and filtering. The MEMS chip and ASIC chip are integrated by gold wire bonding, packaged in a stainless-steel shell, and tested by Hopkinson bar. The test results show that the sensitivity of the accelerometer is 0.2747 μV/g, the non-linearity is 2.79%, and the full range is 200,000 g, and the anti-overload capacity is 250,000 g.