Segregation and diffusion of phosphorus from doped Si1−xGex films into silicon (original) (raw)

Segregation and diffusion of P from in situ doped Si 1Ϫx Ge x (0.25рxр0.8) epitaxial films into Si at 750-850°C were investigated using secondary ion mass spectroscopy and differential resistance measurements. It was found that the surface P concentration in the diffused layer in Si was higher than the P concentration in the Si 1Ϫx Ge x film, which signifies the segregation of P from the Si 1Ϫx Ge x film into Si. The segregation coefficient, defined as the ratio of the active P concentration in the Si to that in the Si 1Ϫx Ge x film, was about 2.5 at 800°C in the case of the Si 0.75 Ge 0.25 film as a diffusion source and increased with increasing Ge fraction. It was found that the P diffusion profiles in Si were normalized by x/ͱt, even though the segregation of P occurred, the diffusion coefficient of P depended on the surface P concentration, and the high concentration diffusion characteristics of P in Si were similar to those reported by using a conventional diffusion source.