| 摘要 |
PURPOSE:To reduce the drop in the withstand voltage of a diffused layer for junction isolation due to a high-voltage wiring without increasing a manufacturing process by providing a diffused layer of the same conductivity type as that of the diffused layer at least one piece around the diffused layer for junction isolation whereon the high-voltage wiring crosses. CONSTITUTION: A diffused layer 3 of one conductivity type for junction isolation is formed in the conductivity type epitaxial layer 2 formed on semiconductor substrate 1 of a one conductivity type and an element region is isolated. The other conductivity type diffused layers 7 and B are provided around the diffused layer 3 and formed using the base diffusion of an N-P-N transistor of a constitution wherein the substrate 1 is a P-type, the epitaxial layer 2 is an N-type and the junction isolation layer 3 is a P-type. The distances between the diffused layer 3 for junction isolation and the diffused layers 7 and 8 are set in such a way that the diffused layers 7 are included in the interiors of depletion layers 4 though the depletion layers are curved inside at the surface by the effect of the electric field of a high-voltage wiring 6 on an insulating film 5. Moreover, the diffused layers 8 are provided in such a way that the diffused layers 6 are included in the interiors of the depletion layers to be extended from the diffused layers 7, which are similarly curved.
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