Czochralski Silicon Crystals Grown in a Transverse Magnetic Field

Abstract

Turbulent convection in silicon melts used in the Czochralski crystal‐growth method was found to be effectively suppressed by applying a transverse magnetic field over 2000G. When turbulent convection is suppressed, it was found that the oxygen concentration in the resulting silicon crystals could be precisely controlled within a range of . The oxygen concentration distribution in the crystals is more uniform than that obtained by the conventional Czochralski method. As‐grown n‐type silicon crystals with a resistivity as high as 5000 Ω‐cm were obtained. Resistivity distribution along the radius of the crystals is more uniform than that produced by the floating zone method. Silicon crystals with low oxygen concentration prepared by the present method have few thermal‐induced defects, which cause the degradation of generation lifetime. The characteristics and yield of p‐i‐n photodiodes and planar‐type GTO's are superior to that obtained in wafers prepared by the floating zone method. We conclude that the Czochralski method using a transverse magnetic field is an effective method of producing high quality silicon crystals which can improve the characteristics of semiconductor devices and their production yield.