| 摘要 |
PURPOSE:To suppress the occurrence of local breakdown at the periphery of a protected impurity regions and to improve surge withstanding voltage, by forming a low concentration impurity region, which has the same conductive type as that of a high concentration impurity region, so as to surround and to contact with the vicinity of the ohmic contact part of at least an input or output wiring layer in the high concentration impurity region. CONSTITUTION:A low concentration impurity region 15 is formed in the vicinity of the ohmic contact part of an input wiring part 19, which is most liable to cause breakdown when a surge voltage is supplied. A junction which causes the breakdown at this part is an n<->/p<+> junction between the low concentration impurity region 15 and a channel stopper region 13. Since the breakdown voltage is higher than that of the conventional n<+>/p<+> junction, the breakdown that is locally occurs at this part is suppressed. Since the sheet resistance of the n<-> type low concentration impurity region 15 is very high, the current flowing through the low concentration impurity region 15 is restricted by said high resistance value, even though the local breakdown occurs at this part. |
