Effects of internal postoxidation on the oxygen deficiency and dielectric strength of buried oxide formed by the separation-by-implanted-oxygen (SIMOX) process

Effects of internal postoxidation on buried silicon dioxide have been studied. The dioxide examined was the buried insulator in a silicon-on-insulator (SOI) structure fabricated by implantation of oxygen ions into Si, or the SIMOX process. Internal postoxidation is an oxidation process applied to the SOI structure after its fabrication. It was observed that the photoluminescence intensity due to neutral oxygen vacancies were also found to increase similarly. The measurements repeatedly done by changing the oxide thickness revealed that the increased part of oxide by the internal oxidation contains the vacancies with a similar density to the original part. It is concluded that the internal oxidation scarcely affects the oxygen deficiency of the oxide. It was also observed that the number of breakdowns at low electric fields remarkably decreased after the internal oxidation, indicating that electrically weak spots such as silicon pipes were effectively reduced.