Effect of Oxidizing Ambient on Oxygen Precipitation in Silicon Crystals

Interstitial oxygen (Oi) concentrations ([Oi]) are measured in silicon crystals subjected to three-step thermal treatments consisting of the first annealing in N2 at 1373 K, the second annealing at 973 K and the third annealing at 1273 K. When silicon surface is oxidized during the third annealing step in O2, oxygen precipitation is retarded in comparison with that obtained in N2. It is found that oxygen precipitation at 1273 K is more retarded with a decrease in [Oi] in silicon crystals. In addition, surface oxidation at 973 K (the second annealing) does not influence the formation of nucleation centers for oxygen precipitates.