PIEZORESISTIVE MICROSENSORS USING P-TYPE CVD DIAMOND FILMS

Chemical-vapor deposited semiconducting diamond is an excellent sensor material for harsh environments and high temperatures. The piezoresistive gauge factors measured at 300 K are in the ranges 200-550 and 6-25 for homoepitaxial and polycrystalline p-type diamond films, respectively. The gauge factor for polycrystalline films decreases with decreasing resistivity, but increases with increasing temperature. A multi-sensor microchip, with a number of diamond test structures and a minimum feature size of 5 mu m, has been fabricated using a six-mask process. The chip, employing diamond both as an electronic and a mechanical material, is expected to help commercialize integrated diamond sensors in the near term.