Atomistic simulations of ion implantation, and annealing of Si over a wide range of ion dose and substrate temperatures, were considered. The Monte Carlo model was extended so as to include the formation of amorphous regions, and this allows simulations of dopant diffusion at high doses. As the dose of ions increases, the amorphous regions formed by cascades eventually overlap, and a continuous amorphous layer was formed. In that case, most of the excess interstitials generated by the implantation were swept to the surface as the amorphous layer re-grows, and did not diffuse in the crystalline region. This process reduced the amount of transient enhanced diffusion during annealing. This model also reproduced the dynamic annealing during high temperature implants. In this case, the local amorphous regions re-grow as the implant proceeds, without the formation of a continuous amorphous layer. For sufficiently high temperatures, each cascade was annealed out independently; interstitials and vacancies could escape from the cascade and thus increase dopant diffusion.

Atomistic Modeling of the Effects of Dose and Implant Temperature on Dopant Diffusion and Amorphization in Si. L.Pelaz, L.A.Marqués, G.H.Gilmer, M.Jaraiz, J.Barbolla: Nuclear Instruments and Methods in Physics Research B, 2001, 180[1-4], 12-6