Mechanisms of buried oxide formation by ion implantation.

We have studied the process of buried oxide formation as a function of implantation and annealing conditions. Concentrating on sub-stoichiometry implants (1x10(18) O/cm(2)), we varied the implantation energies from 170keV to 1MeV. Some precipitation of SiO(2) similar to that observed in Czochralski-grown silicon occurs on implantation. This means that formation of the buried oxide layer and perfection of the overlying crystalline Si layer depends more strongly on the substrate temperature during the implant than on the annealing temperature.