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

摘要

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 $mu{rm g}$ and a velocity random walk of 11.5 $mu{rm g}/surd~{rm Hz}$. The accelerometer operates in a range of ${pm}{rm 5}~{rm g}$ with a nonlinearity of 1140 ppm