Patent ID: 7594966

Claim:
A method for producing a single crystal by pulling a single crystal from a raw material melt in a chamber in accordance with Czochralski method, comprising pulling a single crystal having a defect-free region which is outside an OSF region to occur in a ring shape in the radial direction and in which interstitial-type and vacancy-type defects do not exist by controlling a V/G value as indicated by a growth rate (V) and a temperature gradient (G) near a growth interface, wherein the pulling of the single crystal is performed with being controlled by arranging at least a cooling cylinder to be forced cooled with a cooling medium and an auxiliary member for cooling in the chamber so that an average of cooling rate in passing through a temperature region of the melt point of the single crystal to 950° C. is in the range of 0.96° C./min or more and so that an average of cooling rate in passing through a temperature region of 1150° C. to 1080° C. is in the range of 0.88° C./min or more and so that an average of cooling rate in passing through a temperature region of 1050° C. to 950° C. is in the range of 0.71° C./min or more, and thereby preventing aggregation of point defects, and wherein a growth rate margin for pulling the single crystal having a defect-free region (an upper limit of the growth rate−a lower limit of the growth rate) is in the range of 7% or more of a growth rate average of the single crystal ((the upper limit of the growth rate+the lower limit of the growth rate)÷2).