| 摘要 |
PROBLEM TO BE SOLVED: To raise the reverse surge resistance by setting the specific resistance of an Si substrate in specified range, a p<+> anode layer in specified diffusion depth range, and the thickness of an n-base layer having a substrate specific resistance against a durable reverse surge voltage to a value or more provided by specified equation. SOLUTION: When the specific resistanceρof an Si substrate is set to 20-50Ωcm, the diffusion depth of a p+ anode layer is set to 30-200μm, a durable reverse surge voltage to Vsr , the thickness Wn of an n-base layer having a substrate specific resistance is set to 0.54×(ρ.Vsr )<1/2> or more. If the thickness Wn of an n-base layer having a substrate specific resistance is set to 0.54×(ρ.Vsr )<1/2> or more when the specific resistanceρof an Si substrate is set to 20-50Ωcm, the diffusion depth of a p<+> anode layer is set to 30-200μm, a durable reverse surge voltage to Vsr , a depletion layer remains within the n-base layer, the impurity concn. gradient at a junction reduces, the depletion layer expands also to a p<+> anode and the width stand voltage can be increased as the field intensity lowers.
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