Phosphorus diffusion from doped polysilicon through ultrathin SiO2 films into Si substrates

The diffusion of phosphorus into ultrathin oxides from phosphorus doped polysilicon sources was studied. The two boundary diffusion model can be applied to the diffusion of phosphorus in ultrathin oxides, and the diffusivity and segregation coefficient were obtained using by the model. The dependence of the diffusion coefficient on oxide thickness and drive-in ambients was investigated. The enhanced diffusion, which has been seen for boron diffusion in ultrathin oxides, was not observed for the phosphorus diffusion. For the diffusion in dry O-2 and wet O-2 ambients, the enhanced diffusion was observed and is attributed to melt through diffusion in glassy compounds.