Design and Implementation of a Novel CMOS-MEMS Single Proof-Mass Tri-Axis Accelerometer

This study presents a novel single proof-mass tri-axis capacitive CMOS MEMS accelerometer to reduce the footprint of chip. A serpentine out-of-plane (Z-axis) spring is designed to reduce cross-axis error. A magnetic actuation for Z-axis self-test is also presented. The tri-axis accelerometer has been successfully implemented using TSMC 2P4M process and our in-house post-process. Measurement results show that sensitivities (non-linearity) of etch direction are 0.53mV/G (2.64%) of X-axis, 0.28mV/G (3.15%) of Y-axis, and 0.2mV/G (3.36%) of Z-axis. The cross-axis sensitivities range from 1% to 8.3%, and the measurement range is between 0.8~6G, respectively.