Effect of Fe impurities on the generation of process-induced microdefects in Czochralski silicon crystals

The enhancement effect of Fe impurities on the generation of surface and bulk microdefects, such as oxidation-induced stacking faults, oxide precipitates, precipitate-dislocation complexes and bulk stacking faults, has been observed in annealed silicon wafers prepared from Czochralski grown crystals intentionally contaminated with iron. The effect remains significant even for an Fe concentration as low as 10¹² atoms/cm³. It has been found that Fe facilitates the nucleation of oxide precipitates in silicon. The mechanism of Fe-assisted nucleation of oxide precipitates is discussed. The effect of Fe on the generation of oxidation-induced stacking faults is explained, assuming that both oxide precipitates and Fe:Si precipitates formed near the wafer surface serve as active nucleation sites of these microdefects.