A simple model for boron trapping by He implantation extended defects in Si: the role of boron diffusivity

Abstract High dose helium implantation leads to the formation of extended defects, such as cavities and dislocations that interact with impurities like metals and dopants, affecting their final profiles. The detailed mechanisms governing the boron segregation on these defects are still unclear. In this paper, we evidence that the boron diffusivity is decreased when boron is implanted between the surface and the He-induced defect layer. This layer acts as a sink for interstitials. Using “flat profile” experiments, we propose a simple trapping model of boron at the He-induced extended defects. Numerical modeling has been performed to extract the boron effective diffusion coefficient with regard to the defect band. This work emphasizes the impact of effective diffusivity variation on the boron gettering phenomenon and clarifies boron interaction with He-induced defects.