Ions of BF2+ were implanted into (100) samples at room temperature, with an energy of 40keV, through a 14nm-thick SiO2 layer. Profiling of B by secondary ion mass spectrometry indicated that subsequent annealing (650-850C, 0.5-4h) in a conventional furnace led to a pronounced secondary peak in the B and F profiles; in addition to the near-surface primary peak which was situated in the vicinity of the projected range of the implanted species. This effect was also observed in samples which were rapidly thermally annealed (900C, 15-60s). The depths of the secondary peaks in the B profiles corresponded to the depths of a damaged layer which was observed via cross-sectional transmission electron microscopy. Isochronal furnace annealing revealed that there was no chemical interaction between B and F atoms during annealing. This was also supported by the observation that F atoms did not affect the B segregation coefficient during the oxidation of implanted samples. End-of-range extended dislocations appeared to be responsible for the gettering of atoms during annealing.

Y.Kim, H.Z.Massoud, R.B.Fair: Applied Physics Letters, 1988, 53[22], 2197-9