HIGH-TEMPERATURE PRESSURE SENSOR USING P-TYPE DIAMOND PIEZORESISTORS

Pressure sensors with boron-doped, mesa-etched polycrystalline diamond piezoresistors on top of a silicon square membrane (1300 mu m x 1300 mu m x 30 mu m) were manufactured. Electrical insulation of the boron- doped piezoresistors from the silicon substrate was achieved by an und oped diamond film. The longitudinally arranged piezoresistors were con nected to form a Wheatstone bridge. The sensor shows an excellent line arity of the bridge voltage vs. pressure in the temperature range from - 50 to 170 degrees C for a pressure range of 100 kPa. The low sensit ivity of 1.64 x 10(-5) mV (V Pa)(-1) can be improved using lower dopin g concentrations of the boron-doped piezoresistors.