Precipitation in S-ion implanted Si

Abstract

Using ion implantation for doping semiconductor materials can provide solute concentrations far exceeding the dopant solubility limit. Subsequent annealing of the implanted material produces a high density of dislocation loops. Although the number of dislocations can be reduced by annealing at higher temperatures the material cannot retain the solute in solid solution.We have examined this dilemma by implanting Si with high-energy (6-MeV) S ions to concentrations of ∽ 1020 cm-3, and then heat treating the implanted Si by rapid thermal annealing (RTA) as part of a fabrication procedure for making extrinsic-Si detectors. The maximum solubility limit of S in Si is ∽ 3 x 1018 cm-3. At RTA temperatures < 1000°C faulted dislocation loops formed in the implanted region [1], Above 1000°C the dislocation loops unfaulted and coalesced to form a dislocation network and what appear to be small dislocation loops or small cluster-like structures with maximum diameters of < 100 Å (Fig. 1).