High quality SIMOX wafers, one of silicon-on-insulator (SOI) materials, are produced with combined two technologies, low-dose oxygen implantation and the internal thermal oxidation (ITOX) annealing. Basic features of low-dose ITOX-SIMOX technology, such as excellent layer thickness uniformity and improvement of buried oxide (BOX) quality by ITOX process, will be reviewed. Further quality improvement has been achieved by incorporating nitrogen doped (N-doped) Czochralski (Cz) silicon as a starting substrate for low-dose ITOX SIMOX process. Surface pits due to crystal originated particles (COPs), which are void defects existing in as-grown CZ, can be eliminated with N-doped CZ silicon. The impact on gate oxide integrity (GOI), which is one of important indicators of surface quality, has been also investigated for ITOX process and types of stating substrate. It is demonstrated that ITOX-SIMOX wafers with starting substrate of N-doped CZ silicon exhibit superior GOI.
