The B diffusion in Si after shallow pre-amorphization implants of different species, including F, Ge, GeF2, BF2 and their combination was studied. The results showed that different species had differing impacts on B diffusion. In addition to the chemical effect, the interaction of shallow pre-amorphization implants species with B, leading to immobile B clustering, was another important cause for B diffusion reduction. Fluorine was more effective than Ge in the B diffusion reduction. Adding more F in the amorphous region resulted in more B diffusion reduction. Aside from the effect on the B diffusion, F itself manifests a large amount of out-diffusion for the shallow F implant case and as F was implanted deeper, a bell-shaped F profile exists around the end-of-range damage. The out-diffusion of F was further enhanced by the implanted damage.

B Diffusion in Si with Pre-Amorphization of Different Species. H.J.Li, P.Zeitzoff, L.Larson, S.Banerjee: Journal of Vacuum Science & Technology B, 2004, 22[5], 2380-3