A novel Z-axis capacitive accelerometer using-SOG structure

Abstract

A differential capacitive silicon z-axis micro-accelerometer using SOG (silicon on glass) structure, based on bulk micromachining technology is proposed and a novel structure is designed. The device with a three-layer structure can provide a variable sensitivity as changing the thickness of the beam fabricated, by only one set of masks. The simulation of the static and modal performance of the accelerometer structure is completed with the FEM (finite element method) and the optimized design of the accelerometer is accomplished. The key techniques in the fabrication are investigated and the process flow is designed, furthermore, corner compensation structure was used in the masks to avoid convex corner undercutting, which is simulated and optimized by process simulation (IntelliSuite). The mechanical sensitivity of the accelerometer varies from 2.37/spl times/10/sup -7//w/g/sub n/ to 1.74 /spl times/10/sup -/8m/g/sub n/ as the thickness of the beam from 50/spl mu/m to 20/spl mu/m.