A versatile polysilicon diaphragm pressure sensor chip

Abstract

A multidiaphragm piezoresistive pressure sensor with built-in front side over-pressure protection has been developed which is capable of simultaneous measurement of absolute and differential pressures over a wide range. The sensor chip has six polysilicon pressure sensing diaphragms, three of which measure differential pressures of -1 to 1, -5 to 5, and -30 to 30 psi: the remaining diaphragms measure absolute pressure against vacuum-sealed microcavities and have linear pressure ranges of 0 to 100, 0 to 500, and 0 to 2000 psi. Front side over-pressure protection is at least 6000 psi for every range. First-order temperature correction is achieved by using pressure-insensitive matching resistors. An additional temperature sensor provides on-chip temperature measurement and data for further digital compensation of the sensor array. The sensor chip has been characterized with full-scale output span ranges from 5mV/V for the 1 psi device to 62 mV/V for the 500 psi device. Hysteresis and nonrepeatability are typically within 0.1% of span. The chip thus offers pressure measuring capability over a wide range and the highest built-in over-pressure protection ever reported for a silicon pressure sensor. >