Diffusion of Boron near Projected Ranges of B and BF2Ions Implanted in Silicon

In this study, we examined the diffusion of boron near the projected ranges of high-dose 11B and BF2 ions implanted in silicon. A buried layer of 10B was formed and the redistribution of 10B was used to monitor the diffusion behavior. Boron precipitation at 850 °C produces the pileup of 10B in the peak region of 11B. The formation of a band of boron clusters was indicated by the accumulation of 10B between the projected range and the diffusion tail of the 11B profiles during annealing at 750 °C, following 11B+ implantation. The 10B redistribution at 750 °C also demonstrated the retardation of transient enhanced diffusion (TED) in the peak region. Under BF2+ implantation, TED retardation near the projected range of 11B is suppressed by the decrease in implantation energy, because the surface proximity effect reduces the density of end-of-range (EOR) defects at low implantation energies. Boron clustering is suppressed in front of the diffusion tail of 11B because only a peak of 10B at the EOR dislocations exists at 750 °C following BF2+ implantation.