SiC based pressure sensor for high-temperature environments

Aim of the work presented herein is to develop a SiC based pressure sensor enabling measurements up to 3000 bar at temperatures in the range of 25 degrees C to 400 degrees C. For fabrication of the sensor chip various processing techniques potentially permitting effective membrane structuring are compared. The sensor chip features a centerboss membrane with four piezoresistors made from epitaxial layers. To limit movement of the centerboss, a bottom plate wafer made from SiC is bonded to the sensor chip. The bottom plate is thus acting as an overpressure safety feature. A tungsten-based metallization scheme tested up to 500 degrees C is used. The housing of the sensor is fluid-free and employs a steel membrane for media separation.