Integrated silicon microbeam PI-FET accelerometer

Abstract

Integrated accelerometers showing excellent linearity have been designed and fabricated using silicon planar technology, zinc-oxide sputtering, and anisotropic etching. Small cantilevered beam structures overcoated with piezoelectric ZnO films act as force transducers, and the electrical signal is directly coupled to the gate of a depletion-mode, p-channel MOS transistor. The accelerometers have a nearly flat response from very low frequencies until beam resonances become significant (above 40 kHz). The near-dc response results from completely isolating the piezoelectric film from electrical leakage paths. Measured performance has matched very well with theory. Theoretical analysis has been used to derive useful design tradeoffs.