A high-temperature silicon-on-insulator stress sensor

作者:Wang Zheyao*; Tian Kuo; Zhou Youzheng; Pan Liyang; Hu Chaohong; Liu Litian
来源:Journal of Micromechanics and Microengineering, 2008, 18(4): 045018.
DOI:10.1088/0960-1317/18/4/045018

摘要

A piezoresistive stress sensor is developed using silicon-on-insulator (SOI) wafers and calibrated for stress measurement for high-temperature applications. The stress sensor consists of 'silicon-island-like' piezoresistor rosettes that are etched on the SOI layer. This eliminates leakage current and enables excellent electrical insulation at high temperature. To compensate for the measurement errors caused by the misalignment of the piezoresistor rosettes with respect to the crystallographic axes, an anisotropic micromachining technique, tetramethylammonium hydroxide etching, is employed to alleviate the misalignment issue. To realize temperature-compensated stress measurement, a planar diode is fabricated as a temperature sensor to decouple the temperature information from the piezoresistors, which are sensitive to both stress and temperature. Design, fabrication and calibration of the piezoresistors are given. SOI-related characteristics such as piezoresistive coefficients and temperature coefficients as well as the influence of the buried oxide layer are discussed in detail.