Piling-up of B in the {311} defect region during thermal annealing was observed for the first time. Czochralski-type wafers with a B concentration of 2.7 x 1017/cm3 were implanted with 50keV Si+ to a dose of 5 x 1013/cm2, and annealed at 670C or 720C in a N ambient. During annealing, B atoms accumulated in the region between the projected range and twice the projected range. This led to a B-depleted region which extended from twice the projected range to 0.4μ. During lower-temperature annealing, the number of B atoms in the pile-up region reached its maximum more slowly and had a higher peak value. After reaching the maximum, the number of B atoms fell exponentially; with a characteristic decay time of 14h at 670C or 3h at 720C. A correlation between the annealing-time dependence of the B pile-up, and the evolution of interstitials contained in (311} defects, suggested that the B pile-up was due to B segregation to (311} defects.

Boron accumulation in the {311} defect region introduced by self-implantation into silicon substrates J.Xia, T.Saito, T.Aoki, Y.Kamakura, K.Taniguchi: Japanese Journal of Applied Physics - 2, 1998, 37[8A], L913-5