MOVABLE MICROMACHINED SILICON PLATES WITH INTEGRATED POSITION SENSING

A process for fabricating large silicon plates of varying thicknesses suspended by thin, flexible polyimide beams has been developed.The plates have been integrated with an on-chip ring oscillator which provides a read-out of the plate position. The silicon plates can be moved electrostatically and the position of the plate determined by the frequency shift of the ring oscillator. Initial testing of the device yields a full-scale frequency modulation of approximately 2%, corresponding to a full-scale frequency shift of 13 kHz from a zero-deflection frequency of 680 kHz. © 1990.