TEM STUDY OF COMBINED OXYGEN AND NITROGEN IMPLANTED SILICON

Silicon-on-insulator (SOI) structures can be obtained by the combined implantation of oxygen and nitrogen into silicon. A thorough transmission electron microscope study of the sequential N and O implantation in Si is reported. It is shown that the resulting microstructure strongly depends on the implantation sequence and dose. In general the buried layer remains amorphous. Only in one case did the lower part of the buried layer crystallize in the alpha-Si3N4 phase. When nitrogen is implanted prior to oxygen, alpha-Si3N4 precipitates are formed below the buried layer. They contain a considerable portion of the implanted nitrogen. A particular orientation relationship was found to exist between the alpha-Si3N4 precipitate and the Si matrix; it was determined as (00.1)alpha-Si3N4//{111}Si.