6H-SiC pressure sensor operation at 600/spl deg/C

Experimental results of batch-microfabricated 6H-SiC piezoresistive pressure sensors operational between room temperature to 600/spl deg/C are reported. For a diaphragm thickness of 30 /spl mu/m, the typical room temperature full-scale output for maximum pressure of 1000 psi was 66.41 mV, with a hysteresis and nonlinearity of less than 1%FSO across the range of operating temperature. For a diaphragm thickness of 40 /spl mu/m, the typical room temperature full-scale output for maximum pressure of 1000 psi was between 39 mV and 42 mV, also with a hysteresis and nonlinearity of less than 1% across the range of operating temperature. The temperature coefficient of resistance (TCR) had negative values from room temperature to 350/spl deg/C due to the gradual drop in input resistance. The temperature coefficient of gauge factor (TCGF) averaged about -0.14%//spl deg/C from room temperature to 600/spl deg/C. These values obtained were consistent with the characteristics of 6H-SiC epilayer having an impurity concentration of 2/spl times/10/sup 19/ cm/sup -3/.