SOI pressure sensor

The authors present a technique for fabricating single crystal silicon-on-oxide pressure sensors for high temperature applications. The SOI structure is formed from substrate material by etching techniques and thus good quality single crystal can be achieved without requiring lengthy or expensive processing. Islands of single crystal surrounded by oxide were fabricated. The islands are 7 mu m wide with a depth of 4.5 mu m. There are no pn junction isolations and the device can thus operate at higher temperatures. Longitudinal gauge factors of approximately 90 with a TCGF (temperature coefficient of gauge factor) of -0.22%/K were achieved for the lower doped samples. No leakage between resistors and the substrate could be detected for temperatures up to 300 degrees C.<>