Selective silicon-on-insulator (SOI) implant: a new micromachining method without footing and residual stress

This paper presents a new method for electrically isolating released high aspect ratio single crystal silicon (SCS) MEMS structures. In this method, horizontal dielectric layers are implanted at arbitrary depths in any desired region of a wafer using the sacrificial bulk micromachining (SBM) process. A z-axis microgyroscope is fabricated by the proposed method. The measured noise-equivalent angular rate resolution is 0.0074??s?1, the input range is larger than ?50? s?1, and the measured bandwidth is 7.3 Hz. The proposed method achieves electrical isolation with excellent mechanical stability, and is free from the footing phenomenon and residual stress.