Boron profile changes during low-temperature annealing of BF ⁺2-implanted silicon

BF+2 ions were implanted in (100) silicon at room temperature with an energy of 40 keV through a 140-Å-thick SiO2 layer. Boron profiling by secondary-ion mass spectrometry indicates that subsequent annealing in a conventional furnace in the 650-850°C range for 30-240 min results in a pronounced secondary peak in the B and F profiles, in addition to the near-surface primary peak located in the vicinity of the projected range of the implanted species. This phenomenon was also observed in BF+2 -implanted samples which were rapid thermal annealed at 900°C for 15-60 s. The depths of the secondary peaks in the B and F profiles correspond to the depths of a damaged layer observed by cross-sectional transmission electron microscopy. Isochronal furnace annealing revealed that there is no chemical interaction between B and F atoms during annealing. This is also supported by the observation of F atoms not affecting the B segregation coefficient during oxidation of the BF+2 -implanted samples. The end-of-range extended dislocations appear to be responsible for the gettering of B and F atoms during annealing.

Duke Scholars

Author Hisham Z. Massoud Electrical and Computer Engineering

Author Richard B. Fair Electrical and Computer Engineering