Lattice damage has been introduced in silicon wafers by silicon ion implantation at doses below and above amorphization threshold. In the first case, the annealing behavior of damage is consistent with the presence of amorphous islands near the surface and interstitial clusters in deeper regions. Unlike the former kind of defects, the temperature evolution of the latter strongly affects the diffusion of dopant atoms. Enhanced diffusion for dopant diffusing via interstitialcy mechanism accompanies in fact the interstitial cluster dissolution. The extent of this effect depends on the relative depth position of dopant and defects. When the local concentration of the interstitials increases (e.g., as a consequence of an implant made with the same dose, but with a lower energy) defect clustering begins to compete with their recovery, which makes the fraction of interstitials available for dopant diffusion smaller. Interstitial clustering is the dominant process occurring during annealing at the original amorphous-crystal interface in a high-dose implanted sample. Dislocation loops are then formed and evolve (increase in size, decrease of density) via dissolution of the small clusters in the damage tail. The process is accompanied by a net reduction of the interstitials collapsed in the residual dislocation loops. The consequence is a supersaturation of interstitials, which assists the movement of the dopant, if initially localized at depths greater than loop position. Conversely, when the dopant junction is shallower than the original amorphous layer, negligible enhanced diffusion occurs, which indicates an effective sink action of the loops for the interstitials coming from cluster dissolution.

Servidori, M., Šourek, Z., & Solmi, S. (1987). Some aspects of damage annealing in ion-implanted silicon: Discussion in terms of dopant anomalous diffusion. Journal of Applied Physics, 62(5), 1723–1728.