A Complementary Metal Oxide Semiconductor (CMOS) Compatible Capacitive Silicon Accelerometer with Polysilicon Rib-Style Flexures

Abstract

A silicon-based capacitive accelerometer with bulk silicon proof mass, polysilicon rib-style flexures, and detection circuits is fabricated and tested. A complementary metal oxide semiconductor (CMOS) compatible doping and annealing process for 2-µm-thick polysilicon used as a rib-style flexural beam is developed to optimize the trade-off between the mechanical properties and electrical requirements. According to the anisotropic etch simulation and experimental results, we designed a convex corner compensation pattern and fabricated the proof mass. The open-loop gain of the fabricated switched capacitor integrator (SCI) is more than four thousands, and the common mode range is from 0.8 V to 4.5 V. The fabricated accelerometer has sensitivity of 300 mV/g and capacitance change is 0.36 pF/g.