화학공학소재연구정보센터
Materials Science Forum, Vol.353-356, 753-756, 2001
High temperature 10 bar pressure sensor based on 3C-SiC/SOI for turbine control applications
The FE (Finite Element) simulation, fabrication and characterization of a membrane-type piezoresistive pressure sensor with piezoresistors consisting of 3C-SiC is presented. The nominal pressure of the device is P(nom) = 10 bar, the maximum operating temperature is T(max) > 400 degreesC. The sensitivity at RT is S = 0.5 mV/V bar. The device is suitable for turbine control applications. The membrane of the sensor was defined by ICP etching of a UNIBOND SOI wafer. Due to the vertical sidewalls produced by the etching process, the desired pressure range of the device can simply be adjusted by controlling the etch depth/membrane thickness. An overload protection was realized by choosing a centerboss membrane structure. For a nominal pressure range of P(nom) - 10 bar a membrane thickness, an inner membrane diameter and an outer membrane diameter of 60 mum, 500 mum and 2 mm, respectively, were chosen. The sensors are absolute pressure sensors with a closed cavity which was realized by bonding the structured UNIBOND wafer to a silicon wafer. A 2.2 mum thick SiC layer was deposited onto the SOL of the UNIBOND wafer on top of the sensor cell at 1220 degreesC during an LPCVD process using methylsilane. In situ doping was achieved by adding NH(3) to the process gas. The 3C-SiC piezoresistors were structured by RIE. The resistors were connected in a Wheatstone Bridge configuration. The high temperature stable metallization system TiWN/Au was used.