Abstract
A pressure sensor for use in a high temperature atmosphere (150˜250°C) has been developed. The pressure sensor consists of Cr-O thin film strain gauges, electrode films and an oxidation resistance film, which are all sputter deposited on a metal diaphragm covered with an SiO2 insulator. For the pressure measurement, a photolithographically patterned Wheatstone bridge circuit of the Cr-O thin film strain gauges was used. The output voltages showed good linearity with pressure and little hysteresis even at a temperature of 250°C. In order to prevent oxidation of the strain gauges at high temperatures, some sputtered oxidation resistance films were examined. It was shown that non-oxide films such as AlN and Si3N4 films have good characteristics to prevent oxidation of the strain gauges.
