The effect of P diffusion, in high concentrations, upon the diffusion of an Sb marker layer was investigated (table 97). The marker layer was separated from the surface by a 4 layer of epitaxially grown Si. In order to reduce the effects of implantation enhancement and P precipitation upon the diffusion of the marker layer, the P was implanted into a poly-Si layer that had been deposited onto monocrystalline substrate. It was found that the diffusion of the Sb marker layer was already reduced by the epilayer. On the basis of the diffusion coefficients, upper limits were placed on the fractional diffusivity of Sb. Contrary to the results of previous investigations, the diffusion of the Sb marker layer was found to be enhanced below the regions into which P had been implanted. A comparison of the behavior of float-zone and Czochralski samples showed that the enhanced diffusion of Sb could be explained only by the injection of self-interstitials from the P-doped region. Since the poly-Si layer recrystallized, this self-interstitial injection could be the result of P which diffused mainly via self-interstitials, P precipitation, or both. By using Boltzmann-Matano analyses and Sb diffusivity data, the fractional diffusivity of P via self-interstitials was estimated to be lower than 0.71 at 950C.

Phosphorus-Enhanced Diffusion of Antimony due to Generation of Self-Interstitials. P.Pichler, H.Ryssel, R.Ploss, C.Bonafos, A.Claverie: Journal of Applied Physics, 1995, 78[3], 1623-9

Table 98

Diffusivity of Sb in Strained Si1-xGex Epilayers