Operation of α(6H)-SiC pressure sensor at 500°C

Abstract 6H-SiC piezoresistive pressure sensors have been batch fabricated and tested up to 500 °C in atmosphere. At 1000 psi, the full-scale outputs of a typical sensor are 40.66 and 20.03 mV at 23 and 500 °C, respectively. The full-scale linearity of − 0.17% and hysteresis of 0.17% compare favorably with current silicon technology. No significant degradation in the performance characteristics is observed when the sensors are operated for 10 h at 500 °C. The temperature coefficient of gage factor (TCGF) exhibits negative values of − 0.19 and − 0.11%/ °C at 100 and 500 °C, respectively. Excellent control of the diaphragm thickness is the result of a stabilized electrochemical etching process. The micromachining of bulk 6H-SiC eliminates the thermal-mismatch problem inherent in micromachined heterostructures. This work demonstrates batch manufacture and operation of 6H-SiC pressure sensors for temperatures beyond those of conventional silicon technology.