Application of Rapid Thermal Annealing on LPCVD Polysilicon Films for Piezoresistivity

Abstract

AbstractPolycrystalline silicon is used as a transducing material in pressure microsensors. Its piezoresistive properties are strongly dependent on the processing steps and its properties -which define the sensor characteristics- vary sharply with temperature. LPCVD boron implanted polysilicon thin films have been annealed by RTA at 1100°C or below under conditions ensuring a uniform dopant distribution accross the film thickness. The resistivity as well as the gauge factor have been measured and compared with other authors' results. The gauge factor has been measured using the clamped beam technique between room temperature and 200°C with a specially designed apparatus. Technological parameters such as the Temperature Coefficient of Resistance (TCR) and the Temperature Coefficient of the Gauge Factor (TCK) are deduced as a function of doping. It appears that such coefficients do not satisfactorily describe the resistivity and gauge factor behavior at high temperature.