The Si self-interstitial–C interaction was experimentally investigated and modeled. The interactions between self-interstitials, produced by 20keV Si implantation, and substitutional C in Si were studied using a Si1–yCy layer grown by molecular beam epitaxy and interposed between the near-surface self-interstitial source and a deeper B spike used as a marker for the Si-interstitial concentration. The C atoms, all incorporated in substitutional sites and with a C-dose range of 7 x 1012 to 4 x 1014/cm2, trap the self-interstitials in such a manner that the Si1–yCy layer behaves as a filtering membrane for the interstitials flowing towards the bulk and, consequently, strongly reduced the B-enhanced diffusion. This trapping ability was related to the total C dose in the Si1-yCy membrane. Substitutional C atoms interacting with self-interstitials were shown to trap Si interstitials, to be removed from their substitutional sites, and to precipitate into the C-rich region. After precipitation, C atoms were not able to further trap injected self-interstitials, and the interstitials generated in the surface region could freely pass through the C-rich region and produce B-enhanced diffusion. The atomistic mechanism leading to Si-interstitial trapping was investigated by developing a simulation code describing the migration of injected interstitials. The simulation takes into account the surface recombination, the interstitial diffusion in the molecular beam epitaxially grown material, and C traps. Since the model calculates the amount of interstitials that actually react with C atoms, by a comparison with the experimental data it was possible to derive quantitative indications of the trapping mechanism. It was shown that one Si interstitial was able to deactivate about two C traps by means of interstitial trapping and C clustering reactions.

Interaction between Self-Interstitials and Substitutional C in Silicon - Interstitial Trapping and C Clustering Mechanism. S.Mirabella, A.Coati, D.De Salvador, E.Napolitani, A.Mattoni, G.Bisognin, M.Berti, A.Carnera, A.V.Drigo, S.Scalese, S.Pulvirenti, A.Terrasi, F.Priolo: Physical Review B, 2002, 65[4], 045209 (12pp)