| 摘要 |
PROBLEM TO BE SOLVED: To prevent an adverse effect on a substrate end part, and to suppress a dark current when a depletion layer is formed by applying reverse voltage by a method wherein the interval between the end of the first conductive type semiconductor substrate and the second conductive type impurity region is formed in a specific ratio against the thickness of the first conductive type semiconductor substrate. SOLUTION: A P<+> region 2 is formed on the surface of an N<-> substrate 1, and an N<+> region 3 is formed on the backside of the N<-> substrate 1. Said N<+> region 3 is coupled to an earth 9, a negative potential is applied to the P<+> region 2, and a depletion layer 7 is formed on the N<-> substrate 1. At this point, when the interval between the end 1a of the N<-> substrate 1 and the end 2a of the P<+> region 2 is set at L and the thickness of the N<-> substrate is set at (t), L/t is set at 0.7 or higher and 2 or lower. Accordingly, the affection of the defect generated on the end 1a of the N<-> substrate 1, which is the part cut from a wafer, can be prevented, and the sudden increase of a dark current can also be prevented.
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