A Bulk-Micromachined Fully Differential MEMS Accelerometer With Split Interdigitated Fingers

This paper proposes a novel bulk-micromachined MEMS accelerometer employing split interdigitated sense fingers that provide a fully differential signal interface, where the accelerometer can be fabricated by a modified silicon-on-glass process using a 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 highly sensitive split interdigitated sense finger triplets that are connected with multilayer metal interconnects on an SOI-glass bonded wafer. The fabricated accelerometer is packaged for system level tests with a fourth-order Sigma-Delta readout circuitry to evaluate its performance. The measurement results show that the accelerometer achieves a bias instability of 50 mu g and a velocity random walk of 11.5 mu g/root Hz. The accelerometer operates in a range of +/- 5 g with a nonlinearity of 1140 ppm