Effects of boron-interstitial silicon clusters on interstitial supersaturation during postimplantation annealing

Boron marker-layer structures have been used to investigate the effects of B doping on the evolution of the implantation damage and of the associated transient enhanced diffusion. The samples were damaged by Si implants at different doses in the range ${\text{2×10}}^{13}{\text{–1×10}}^{14} {\mathrm{cm}}^{\mathrm{-2}}$ and annealed at $\text{740\hspace{0.05em}°}\mathrm{C}$ for times between 2 s and 4 h. The values of interstitial supersaturation, from the beginning of the annealing up to the complete damage recovery, have been determined for the different Si doses for a given B doping level. Damage removal has been followed by double crystal x-ray diffraction. Our results confirm that the formation of boron-interstitial silicon clusters traps a relevant fraction of the interstitials produced by the implantation. This trapping action gives rise to a strong reduction of the interstitial supersaturation, prevents the interstitial clusters from being transformed in {113} defects and modifies the time evolution of the transient enhanced diffusion. X-ray analyses indicate also that the size of the boron-interstitial silicon clusters remains below 2 nm.