LOW-TEMPERATURE CRYSTALLIZATION OF IN SITU PHOSPHORUS-DOPED LOW-PRESSURE CHEMICAL-VAPOUR DEPOSITED AMORPHOUS SILICON.
Canadian Journal of Physics , Volume 65 - Issue 8 p. 1030- 1032
A method has been developed for producing low-resistivity phosphorus-doped polysilicon films with a minimum thermal budget. The method involves low-pressure chemical-vapor deposition of amorphous silicon at 500 degree C followed by crystallization at 650 degree C. Films formed in this manner are compared to films deposited polycrystalline at 627 degree C. In both cases, in situ doping is achieved by addition of PH//3 diluted in SiH//4 to the gas mixture. For a given SiH//4:PH//3 flow ratio, the phosphorus concentration determined from secondary-ion mass spectroscopy is four times larger in the amorphous-deposited material. Moreover, the resistivity is substantially lower in this material even when the dopant concentrations are similar. The latter result may be due in part to reduced dopant segregation to grain boundaries. The internal strain determined from the Raman line width is larger in the polycrystalline-deposited material but could be reduced by high-temperature annealing.