Reordering of amorphous layers of Si implanted with 31P, 75As, and 11B ions

Abstract

The effect of impurities on the epitaxial regrowth of Si from amorphous layers created by ion implantation into 〈100〉 and 〈111〉 Si was studied by channeling effect measurements with 2-MeV 4He ions. The Si wafers were first implanted at −180 °C with 28Si ions to form amorphous layers approximately 4000 Å thick and then were implanted with 31P, 75As, or 11B ions to concentration levels of about 0.2–0.5 at.%. For these layers with impurity species the growth rate is found to be significantly higher than for those without. The measured regrowth rate at 500 °C for 〈100〉 Si with an impurity concentration of ∼2×1020 cm−3 of 31P or 75As is a factor of 6 greater, and of 11B a factor of 20 greater, than the regrowth rate in amorphous layers without impurities. For the case of 31P implanted 〈100〉 Si the activation energy of regrowth is close to that (2.35 eV) found for impurity-free amorphous layers and for 11B implanted samples the energy is 1.9 eV. For 〈111〉 31P implanted Si specimens there is an increase in growth rate over that found in impurity-free samples and a high level of residual disorder.