Patent ID: 7226507
Filing Date: 2007-06-05
Classification: C30B

Abstract:
1. A method for producing a single crystal of which a whole plane in a radial direction is a defect-free region with pulling the single crystal from a raw material melt in a chamber by Czochralski method, wherein at least any one of a distance (L 1 ) between a melt surface of the raw material melt and a heat insulating member provided in the chamber, a position of a heater heating the raw material melt, and a flow rate (F) of an inert-gas introduced into the chamber is changed in a direction of the crystal growth axis during pulling the single crystal so that a margin of a pulling rate that the single crystal of which the whole plane in a radial direction is a defect-free region can be pulled always satisfies a relational formula “the margin of the pulling rate≧0.35×exp(0.016×a diameter of a straight body of the single crystal [mm])+0.01”.