Design and implementation of a novel poly-Si single proof-mass differential capacitive-sensing 3-axis accelerometer

This study presents a novel single proof-mass 3-axis capacitive-type accelerometer design consisting of poly-Si rib-proofmass, springs, high-aspect-ratio in-plane sensing electrodes, and plate-type out-of-plane sensing electrodes. This single proof-mass accelerometer design has three merits to increase the sensitivity, (1) large area plate-type out-of-plane gap-closing sensing electrodes with differential capacitive-sensing capability; (2) large area high-aspect-ratio in-plane gap-closing sensing electrodes; (3) electrical routings for 3-axis sensing are considered, and (4) thick ribs to remarkably increase the proof-mass. The single proof-mass 3-axis accelerometer is implemented using well-known two poly-Si and trench refill processes. Measurements (0.1G~3G) show that sensitivities (non-linearity) of etch direction are X-axis:4.31mV/G (2.72%), Y-axis:4.30mV/G (2.57%), and Z-axis:3.48mV/G (2.91%).