Annealing properties of defects during Si-on-insulator fabrication by low-dose oxygen implantation studied by monoenergetic positron beams

The depth distributions and species of defects in Si on insulator (SOI) fabricated by low-dose oxygen implantation were determined from measurements of Doppler broadening spectra of the annihilation radiation and lifetime spectra of positrons. The temperature range for the annealing of the defects in the subsurface region (< 100 nm) was divided into three stages. Annealing behaviors of the defects in stages I (600-800 degrees C) and II (800-1100 degrees C) were identified as the introduction of vacancy clusters and their recovery process, respectively. The major species of the defects in stage III (1100-1300 degrees C) was identified as oxygen-related defects, and the mean size of the open volume of such defects was close to that of a hexavacancy. The oxygen-related defects in the SOI layer were found to be present even after annealing at 1350 degrees C. The effect of the presence of vacancy-type defects on the depth distribution of oxygen atoms is also discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)03104-2].