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

6H-SiC piezoresistive pressure sensors have been batch fabricated and tested up to 500 degrees 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 degrees 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 degrees C. The temperature coefficient of gage factor (TCGF) exhibits negative values of -0.19 and -0.11%/degrees C at 100 and 500 degrees 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. (C) 1998 Elsevier Science S.A. All rights reserved.