A TRENCH AND RELEASE ETCHING TECHNIQUE USING IN-SITU SIDEWALL PASSIVATION OF HIGH ASPECT RATIO BEAMS FOR MEMS

摘要

This paper describes an in-situ trench and release etching technique to fabricate high aspect ratio MEMS beams for high performance accelerometer. Long rectangular sensor beams were formed by magnetically enhanced reactive ion etching into silicon substrate. In conventional process, lateral encroachment was severe underneath the SiO{sub}2 etching mask. In the new in-situ process, the sidewalls of the beams were passivated by the inhibiting layers formed during HBr-based trench etching. They were not chemically attacked by subsequent SF{sub}6 release etching. The in-situ etching process dispensed with both sidewall deposition and floor etching steps. Capacitance of the sensor beams showed a parabolic increase with the increase of applied voltage. Capacitance and yield results obtained by the new in-situ process were found to be comparable to those of the conventional process.