Al redistribution into SiO2/Si system during oxidation of high dose Al-implanted silicon

The distribution during wet oxidation at 920°C of Al implanted in Si at 35 keV and 3×10¹⁵/cm² fluence has been investigated. About 40% of the fluence is lost just after the first stage of the thermal process; another 40-50% is distributed inside the growing oxide at a concentration of about 10²⁰/cm³. A relevant fraction of the remaining Al atoms segregates inside highly defective zones. In addition small precipitates are detected by TEM in the oxide layer. The inclusion of these precipitates in the SiO₂ layer is the reason of the formation of very rough oxide surfaces