Microfabricated SOI pressure sensor using dynamically balanced lateral resonator

Abstract

A resonant pressure sensor using a dynamically balanced lateral resonator is presented, which employs differential electrostatic comb structure for linear driving and sensing. The sensor is successfully microfabricated through a simple yet reliable micromachining process based on a commercially available silicon-on-insulator wafer with only two masks. Special anchor structure is developed to suppress the vertical position shift of the resonator when the diaphragm deflects, which using suspended connecting trusses to attach the stress-sensitive beam ends of the resonator. The sensor chip is mounted into a custom 16-pin Kovar package with epoxy resin for preliminary measurements. Testing results show that the resonator has a fundamental resonant frequency of 34.17 kHz, and the quality factor is about 1253 at atmospheric pressure, which rises to above 50 000 below 5 Pa. Over the pressure range of 100-380 kPa, the static pressure sensitivity is approximately 10.17 Hz/kPa, with the nonlinearity of 0.02%FS, the hysteresis error of 0.05%FS, and the repeatability error of 0.17%FS.