Channeling and nuclear reaction analysis of shallow B- and BF2- implanted Si

Abstract

Ion channeling and nuclear reaction analysis (NRA) have been used to study rapid thermal annealing (RTA) of 10-keV B- and 45-keV BF2-implanted, crystalline, and preamorphized Si. Samples were capped with SiO2 and annealed in a nitrogen atmosphere with an AG Associates 210T Heatpulse system. Damage depth distributions were determined with He+ ion channeling. Extensive disorder was observed near the B projected range following a 1050 °C/20-s RTA cycle of B-implanted crystalline Si. For the same annealing conditions, much less residual damage was apparent for B-implanted preamorphized Si. No disorder was observed in the near-surface region (<30 nm) following a 1050 °C/20-s RTA cycle of BF2-implanted, crystalline, and preamorphized Si. Post-anneal damage at the original amorphous/crystalline interface was greater for BF2-implanted crystalline Si compared to BF2-implanted preamorphized Si. The relative retained B and F doses were determined with NRA using the 11B(p,α)8Be* and 19F(p,α0)16O reactions, respectively. A significant loss of B was observed following RTA of BF2-implanted preamorphized Si. No loss of B was apparent for all other annealed samples. A loss of F was observed for all annealed samples. For identical annealing conditions, the relative retained F dose of BF2-implanted preamorphized Si was less than that of BF2-implanted crystalline Si.