Published online by Cambridge University Press: 15 February 2011
Polycrystalline silicon, used as a transducing material in high temperature Silicon On Insulator piezoresistive pressure sensor, is well known to be strongly dependent on the process parameters. Indeed depending on the deposition, doping and annealing conditions, the structural parameters of polysilicon namely grain size and texture may be very different. We use here a complete model of the piezoresistivity in polysilicon including a significant effect at grain boundaries to study the influence of structural parameters on the resistivities, gauge factors and their thermal drifts between room temperature and 200°C. The model validity has been verified experimentally for two types of polysilicon materials (LPCVD at 620°C and LPCVD at 580°C), subsequently B-doped (from 9×1018 to 9×1019 cm−3) and annealed by Rapid Thermal Annealing at 1100°C/20s and 1100°C/40s respectively. A good agreement between theoretical and experimentally determined resistivities and gauge factors at a variable temperature is observed for the two types of polysilicon materials considering different grain sizes with a <110> dominant texture for LPCVD 620°C series and no preferential texture for LPCVD 580°C series.