Patent ID: 7291220

Claim:
A process of producing a silicon wafer from a single-crystal including a ring-shaped OSF region and having a predetermined nitrogen concentration and a predetermined oxygen concentration prepared by the Czochralski method in a reducing-gas or inert-gas atmosphere, comprising: inserting a silicon wafer including the ring-shaped OSF region and having the nitrogen concentration ranging from 2.9×10 14 to 5.0×10 15 atoms/cm 3 and the oxygen concentration of 1.27×10 18 to 3.0×10 18 atoms/cm 3 , into a heat-treatment furnace in which the temperature was maintained at 600 to 800° C. in the reducing-gas or inert-gas atmosphere; and heat-treating the wafer, while maintaining the rate of increasing the temperature at 0.5° C./min to 2.0° C./min until the wafer is heated to a heat-treatment temperature of 1000 to 1200° C.