A piezoresistive accelerometer with a novel vertical beam structure

Abstract

A beam-mass piezoresistive micro-accelerometer sensitive to acceleration components in the chip plane and vertical to the beam direction has been developed. The beam is in the <100> direction with sidewalls vertical to the [001] wafer surface. The top side of the beam is widened slightly to make enough room to accommodate the piezoresistors. Therefore, the beam has a T-shaped cross-section. Two n-type piezoresistors on the top side of the beam, forming a half bridge, serve as sensing elements. The sensitivity of the device is about 0.5 mv/g/5v and the resonant frequency is about 1.2 kHz.