It had recently been demonstrated that substitutional B in crystalline Si could migrate for long distances even at room temperature and below during secondary ion mass spectrometry profiling. The phenomenon was suppressed after amorphization or by cooling the sample. The above data force to reconsider the observations obtained in the last decades by secondary ion mass spectrometry in the light of possible long-range migration artefacts. Here it was shown that the use of oxygen flooding (OF) during the analysis enhanced the injection of self-interstitials (I) responsible for the migration of B, producing profiles that were more broadened and less accurate than in ultrahigh vacuum. On the other hand, by properly controlling OF, new insights were obtained into the mechanisms of B diffusion and interaction with intrinsic traps at RT. Moreover, by cooling the sample the migration of B was suppressed even while using OF, allowing measurements of B deltas in c-Si of unprecedented level of accuracy and sensitivity. Finally, the role of migration phenomena in the profiling of ultra-low energy B implants for ultra-shallow junctions was clarified.

Room Temperature Migration of Boron in Crystalline Silicon during Secondary Ion Mass Spectrometry Profiling. E.Napolitani, D.De Salvador, M.Pesce, A.Carnera, S.Mirabella, F.Priolo: Journal of Vacuum Science & Technology B, 2006, 24[1], 394-8