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). (C) 2002 Elsevier Science B.V. All rights reserved.