Thermal annealing behavior of defects induced by ion implantation in thermally grown SiO₂ films

When ion-implanted thermal SiO₂ films are irradiated by photons at 5.0 eV, photoluminescence (PL) appears at 4.3, 2.7, and 1.9 eV. These PLs are related with defects in the SiO₂ films. When the SiO₂ films are annealed at high temperatures, both the 4.3 and 2.7 eV PL intensities decrease gradually with an increase in the annealing temperature and disappear at 500°C, while the 1.9 eV PL increases or stays constant up to 400°C and suddenly disappears at 500°C. Such annealing behavior is not influenced by the annealing atmosphere. In the case of the films degassed in high vacuum before implantation, it is observed that the PL bands survive the annealing at 500°C. This result suggests that dissolved gases in the film play an important role in the annihilation of defects induced by ion implantation.