| 摘要 |
PROBLEM TO BE SOLVED: To reduce current loss by forming a region where p/n type inversion occurs within a range of deeper depth.SOLUTION: A p-type wafer is doped with nitrogen or carbon and is heat-treated at a processing temperature of 1,100 to 1,250°C for a processing time of 1 to 5 hours in an atmosphere of argon gas, hydrogen gas, or gaseous mixture thereof, and then a resistance distribution in a depth direction from a surface has a p-type surface region of about 0.1 to 10 kΩ, a peak region where the resistance value increases and decreases in the depth direction to form a peak, and a p/n-type inversion depth region by an oxygen donor, so that the peak position in the peak region is within a range of depth of 10 to 70 μm from the wafer surface. |
