A CMOS-MEMS accelerometer with tri-axis sensing electrodes arrays

Abstract

This study presents a single proof-mass CMOS-MEMS accelerometer with integrated tri-axis sensing electrodes arrays. The in-plane finger-type and out-of-plane plate-type gap-closing sensing electrodes are employed in this study. The standard TSMC 0.35μm 2P4M CMOS process and in-house post-CMOS process was used to implement the device. The capacitive in-plane and out-of-plane sensing gap can be defined by the minimum line-width and the thickness of CMOS process. The structure size is only 500×500μm 2. Measurement results show the sensitivities (non-linearities) are 2.47mV/g (1.3%) in X-axis, 2.87mV/g (1.4%) in Y-axis, and 3.89mV/g (3.4%) in Z-axis. The noise flow for in-plane and out-of-plane sensing are 0.59mg/rtHz and 0.8mg/rtHz.