A comprehensive model was presented for describing B implantation, diffusion and clustering. The model, as demonstrated by means of Monte Carlo simulations, could explain and predict the behavior of B under a wide range of implantation and annealing conditions by proposing that immobile precursors of B clusters were formed before the onset of transient enhanced diffusion. The model also included the usual mechanisms of Si self-interstitial diffusion and B kick-out. The immobile B cluster precursors, such as a B atom plus two Si self-interstitials, formed during implantation or in the very early stages of annealing when the Si interstitial supersaturation was very high. They then acted as nucleation centers for the formation of B-rich clusters during annealing. The B-rich clusters constituted the electrically inactive B component, so that clustering markedly affected both the junction depth and the dopant level in high-dose implants.

L.Pelaz, M.Jaraiz, G.H.Gilmer, H.J.Gossmann, C.S.Rafferty, D.J.Eaglesham, J.M.Poate: Applied Physics Letters, 1997, 70[17], 2285-7