PNNL

Abstract

Effective control of diffused phosphorus profiles in crystalline silicon requires detailed understanding of the doping process. We develop a model and analyze concentration profiles within the deposited phosphosilicate glass (PSG) for a range of POCl3 conditions. During predeposition, a PSG layer with composition nearly independent of process conditions forms. This layer is separated from Si by a thin SiO2 layer. There is also strong accumulation of P at the SiO2-Si interface. A simple linear-parabolic model cannot fully explain the kinetics of thickness and dose; while an improved model including oxygen dependence and dose saturation gives better fits to the experiments.