The effects of impurity diffusion and surface damage on oxygen precipitation in silicon

The rate of oxygen precipitation in Czochralski-grown silicon with oxygen supersaturation ratios s>5 and s<5 at 1000°C was studied as a function of surface processing. Reference samples were compared with samples diffused with high-concentration phosphorus or arsenic layers in N2 or O 2 ambients. Oxygen precipitation was also studied in samples with air-abraded surfaces. It was found that for s<5, oxygen precipitation was inhibited by the presence of a P diffusion, but not by As diffusion. For s>5 the concentration of oxygen in SiO2 precipitates in P diffused wafers did not equal the change in interstitial oxygen, and a high density of stacking faults were seen in the bulk. It is concluded that the point defects generated from damaged surfaces and P-diffused surfaces are not the same as those generated from an undoped surface during oxidation. A model describing the effect of surface-generated vacancies and silicon self-interstitials on oxygen precipitate nucleation and growth is discussed.

Duke Scholars

Author Richard B. Fair Electrical and Computer Engineering