Atomistic modeling of the effects of dose and implant temperature on dopant diffusion and amorphization in Si

We discuss atomistic simulations of ion implantation and annealing of Si ov er a wide range of ion dose and substrate temperatures. The DADOS Monte Car lo model has been extended to include the formation of amorphous regions, a nd this allows simulations of dopant diffusion at high doses. As the dose o f ions increases, the amorphous regions formed by cascades eventually overl ap, and a continuous amorphous layer is formed. In that case, most of the e xcess interstitials generated by the implantation are swept to the surface as the amorphous layer regrows, and do not diffuse in the crystalline regio n. This process reduces the amount of transient enhanced diffusion (TED) du ring annealing. This model also reproduces the dynamic annealing during hig h temperature implants. In this case, the local amorphous regions regrow as the implant proceeds, without the formation of a continuous amorphous laye r. For sufficiently high temperatures, each cascade is annealed out indepen dently: interstitials and vacancies can escape from the cascade and thus in crease dopant diffusion. (C) 2001 Elsevier Science B.V. All rights reserved .