| 摘要 |
A semiconductor device of the present invention is disclosed which includes a semiconductor device of a predetermined conductivity type having a predetermined impurity concentration, a source/drain area formed on the upper surface portion of the semiconductor substrate and a guard ring formed around the source/drain area and having the same conductivity as that of the semiconductor substrate. A gate oxide film is formed on the source/drain area and guard ring and an interconnection layer, such as polysilicon, is formed on the gate oxide film. The guard ring has its impurity concentration set to be higher than that of the semiconductor substrate. The guard ring per se has a portion intersecting with the interconnection layer through a thicker portion of a gate oxide film disposed over the intersecting portion of the guard ring, and a remaining portion, the intersecting portion of the guard ring being higher in impurity concentration than the remaining portion of the guard ring. The gate oxide film is so formed as to be thicker over the intersecting portion of the guard than over the source/drain area in terms of their thickness.
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