The variation of fundamental properties of silicon melts by adding boron into the melts has been studied. The surface tension decreases and the viscosity has a tendency to decrease with boron addition. These property variations cause melt flow variations in a crucible. The temperature distribution near the growing interface varies during crystal pulling process with and without adding boron. The parameter V/G (growth velocity/temperature gradient in the crystal) near the crystal growing interface apparently decreases with boron addition. The defect formation due to interstitial and the effect of boron will be discussed. (C) 2002 Elsevier Science B.V. All rights reserved.