Effect of the axial temperature gradient on the formation of grown-in defect regions in Czochralski silicon crystals; reversion of the defect regions between the inside and outside of the Ring-OSF

Abstract

The effect of axial temperature gradient ( G) on the formation of grown-in defect regions in Czochralski silicon (CZ-Si) crystals was investigated. A CZ-Si crystal was grown with the temperature gradient at the center ( G c) far higher than that at the outside ( G s) by tuning the hot zone of the pulling furnace. It was found, by changing the growth rate ( f p), that the shape of Ring-like region of oxidation-induced stacking faults (Ring-OSF), including the crystal axis and the diameter, became a W-band which has not been reported previously. This W-band results in the reversion of grown-in defect regions inside and outside of the Ring-OSF in the wafers. That is, the wafers included a dislocation-cluster region inside the Ring-OSF, while the void region was outside the Ring-OSF. The appearance of the W-band of Ring-OSF was readily explained using the values of f p/ G c and f p/ G s.