A bulk-micromachined fully-differential MEMS accelerometer with interdigitated fingers

This paper proposes a novel bulk-micromachined MEMS accelerometer employing interdigitated sense fingers that provide a fully-differential (FD) signal interface, where the accelerometer can be fabricated by a modified Silicon-on-Glass (M-SOG) process utilizing a <;111>; Silicon-on-Insulator (SOI) wafer. The accelerometer combines the feasibility of fabricating large mass and high aspect ratio structures using bulk-micromachining together with the high sensitive interdigitated sense finger triplets that are connected with multi-layer metal interconnects on an SOI-glass bonded wafer. The fabricated accelerometer is packaged for system level tests with a 4^th order Σ-Δ readout circuitry to evaluate its performance. The measurement results show that the accelerometer achieves a bias instability of 66.1 μg and a velocity random walk of 17.5 μg/√Hz, while operating in a range of ±8 g.