PIEZORESISTANCE OF BORON-DOPED PECVD AND LPCVD POLYCRYSTALLINE SILICON FILMS

An investigation into the structural, electrical and piezoresistive pr operties of SOI (silicon-on-insulator) type structures is reported. Th e aim of our work is to evaluate how deposition and annealing conditio ns may change these properties. Various characterization experiments h ave been undertaken in order to investigate LPCVD and PECVD thin films . A theoretical model for the piezoresistivity is developed that requi res experimentally determined parameters (active dopant concentration, grain size, texture, resistivity, barrier height). Moreover, the hypo thesis of constant strain or stress has been considered for the spatia l average. The measured gauge factors, in the range 25-45 for LPCVD fi lms and 20-30 for PECVD films, fall in the tight interval defined by t he theoretical estimates.