Effect of nitrogen doping on piezoresistive properties of a-Si x C y thin film strain gauges

In this study, the effect of nitrogen doping on piezoresistive properties of non-stoichiometric amorphous silicon carbide (a-Si x C y ) thin-film strain gauges was investigated. The films were prepared by plasma-enhanced chemical vapor deposition (PECVD) and the strain gauges were patterned by fabrication processes like conventional photolithography, metallization and reactive ion etching (RIE). The structure of the strain gauges consists of a a-Si x C y thin-film resistor with one Ti/Au electrical contact at each extreme of the resistor. In order to determine the piezoresistive properties, each strain gauge type was bonded near the clamped edge of a stainless steel cantilever beam and on the free edge calibrated weights were applied. The influence of the temperature on piezoresistive properties also was evaluated through the temperature coefficient of resistance (TCR) measurements from room temperature up to 250oC. It was observed that nitrogen doping increased the piezoresistive coefficient and TCR of a-Si x C y thin film strain gauges.