PURPOSE: To prevent the breakdown strength from decreasing due to inversion of an epitaxial layer by providing a polysilicon wiring, which crosses a wiring extended through the area above an element isolating region and at the potential homopolar with the element isolating region, on a substrate, and maintaining this wiring at the polar potential reverse to the element isolating region.

CONSTITUTION: A thick insulating film 6 of a silicon oxide film is formed on a silicon substrate 1, and thereon a phosphorous glass (PSG) film 7 is formed, and further thereon an aluminum wiring 8 is formed. And a polysilicon wiring 9 is formed on an insulating film 6 by patterning such that it crosses the aluminum wiring 8 between an N+-type diffusion layer 10 and an element isolating region 5. This wiring is electrically connected to an epitaxial layer 2, and is always kept at the same potential as the epitaxial layer 2. By this constitution, the wiring 9 is formed directly not through a PSG film 7. Accordingly, by the effect of the high potential of the polysilicon wiring 9, an inversion layer 12, which arises below the aluminum wiring 8, becomes hard to be inverted, whereby breakdown generation by the inversion layer can be prevented.