The axial temperature gradient in the CZ-Si melt near the crystal-melt interface was increased by controlling the crucible and crystal rotation rate. For the crystal grown under the increased temperature gradient in the melt with a very low crucible rotation rate, asymmetric distributions of grown-in microdefects were formed. This result has never been reported, and cannot be explained simply by any theory such as Voronkov's theory. In addition, it is shown that the shape of the crystal-melt interface is not the parameter determining the dominant type of point defects. Therefore, a new aspect of the formation behavior of point defects is discussed in terms of asymmetry of the melt temperature distributions. (c) 2006 Elsevier B.V. All rights reserved.