High Gauge Factor Piezoresistors Using Aluminium Induced Crystallisation of Silicon at Low Thermal Budget

Abstract

This paper reports on polysilicon piezo-resistors that are fabricated at a low thermal budget using aluminium-induced-crystallization (AIC) of ultra-high-vacuum e-beam evaporated silicon films. By in-situ phosphorus doping of precursor amorphous silicon films e-beam evaporated at room temperature on aluminium layer, we are able to increase and control the gauge factor of the polysilicon films formed by AIC at 450 °C. Piezo-resistors made from the polysilicon films are integrated on microcantilever beams to measure their gauge factors. Gauge factors as high as 62 is obtained for 2 × 10 18 /cm 3 phosphorus doping level in the precursor amorphous silicon film. The measured gauge factors are significantly higher than previously reported values for polysilicon films.