| 摘要 |
PURPOSE:To manufacture a protective circuit capable of operating at high speed by a small occupying area and resisting electrostatic breakdown by forming one conductivity type impurity region shaping a P-N junction with one region in a semiconductor substrate into the semiconductor substrate while forming a conductor layer having the same conductivity type as the impurity region, so as to be brought into contact with the impurity region. CONSTITUTION:P<-> type wells 2 and 5 are shaped into an N<-> type semiconductor substrate 1, a P<+> type impurity region 3 is formed into the P<-> type well 2, and a P<+> type impurity region 6 is shaped into another P<-> type well 5. The P<-> type wells 2 and 5 are insulated electrically from the periphery by a field oxide film 8, the P<-> type well 5 is grounded, and supply voltage VDD is applied to the N<-> type semiconductor substrate 1. A P<+> polycrystalline silicon layer 4 is formed brought into contact with the upper section of the P<+> type impurity region 3, and an N<+> polycrystalline silicon layer 7 is shaped brought into contact with the upper section of the N<+> type impurity region 6. Insulating films 9 are formed at the upper predetermined positions of the P<+> polycrystalline silicon layer 4, the N<+> polycrystalline silicon layer 7 and the field oxide film 8, and wired by using aluminum 10.
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