It was noted that high-dose He implantation led to the formation of extended defects, such as cavities and dislocations, that interacted with impurities such as metals and dopants. The details of the mechanisms which governed B segregation at these defects remained unclear. It was shown here that the B diffusivity decreased when B was implanted between the surface and a He-induced defect layer. The latter acted as a sink for interstitials. On the basis of so-called flat profile experiments, a simple trapping model was proposed for B at He-induced extended defects. Numerical modeling was used to deduce the effective B diffusion coefficient with regard to the defect band. This revealed the effect of effective diffusivity variation upon B gettering, and clarified the B interaction with He-induced defects.

A Simple Model for Boron Trapping by He Implantation Extended Defects in Si - the Role of Boron Diffusivity. F.Cayrel, D.Alquier, D.Mathiot, L.Ventura, L.Vincent, G.Gaudin, R.Jérisian: Nuclear Instruments and Methods in Physics Research B, 2004, 216, 291-6