| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device in which a circuit element can be protected against overvoltage. SOLUTION: In the semiconductor device, an N type buried diffusion layer 4 is formed over a substrate 2 and an epitaxial layer 3. A P type buried diffusion layer 5 is formed over a wide region on the upper surface of the N type buried diffusion layer 4 and a PN junction region 17 for overvoltage protection is formed. A P type diffusion layer 6 is formed to be coupled with the P type buried diffusion layer 5. Breakdown voltage of the PN junction region 17 is lower than that between the source and drain. With such a structure, breakdown current is prevented from concentrating and a semiconductor device can be protected against overvoltage. COPYRIGHT: (C)2006,JPO&NCIPI
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