To form a wafer having no COP defect from the surface toward the predetermined depth of the same and BMD nuclei which exist in a lower region.
The wafer is preheated to about 500°C in a diffusion furnace under an atmosphere of Ar, N2 or an inert gas containing these gases, and thereafter, the temperature of the wafer is increased under an atmosphere of Ar or an inert gas containing the gas at a rate of 50-70°C/min at a temperature of 500-800°C, 50-10°C/min at 800-900°C, 10-0.5°C/min at 900-1,000°C and 0.1-5°C/min at 1,000-1,250°C, then, a high temperature is maintained for 1-120 min. at 1,200-1,250°C. Thereafter, the temperature is reduced under the atmosphere of Ar, N2 or an inert gas containing these gases at a rate of 0.1-0.5°C/min at a temperature of 1,250-1,000°C, 10-0.5°C/min at 1,000-900°C, 50-10°C/min at 900-800°C and 50-70°C/min at 800-500°C.
KIM GUN
YOON SUNG-HO
