| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that, when overvoltage is applied to an electrode pad in a conventional semiconductor device, a circuit element is broken in a chip. SOLUTION: In this semiconductor device, an n-type epitaxial layer 3 is divided into a plurality of element formation areas by isolation areas 4 and 5. A MOS transistor 1 is formed in one of the element formation areas. A protective element including pn junction areas 34 and 35 is formed around the MOS transistor 1. The pn junction areas 34 and 35 are lower in junction withstand voltage than the pn junction areas 32 and 33 of the MOS transistor 1. Because of such the structure, when negative ESD surge is applied to a pad for a source electrode, the pn junction areas 34 and 35 are broken down to protect the MOS transistor 1. COPYRIGHT: (C)2008,JPO&INPIT
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