| 摘要 |
PROBLEM TO BE SOLVED: To enhance durability in a protective circuit which protects an LSI from the breakage caused by static electricity. SOLUTION: A p-type well region 13 and, adjacent to this, an n-type well region 14 deeper than this p-type well region 13 are made on the surface of a p-type substrate 11. A p+-type diffusion layer 15 and an n+-type diffusion layer 16 are made on the surface of the p-type well region 13. A p+-type diffusion layer 17 and an n+-type diffusion layer 18 are made on the surface of the n-type well region 14. This way, an NPN bipolar transistor Q1 and a PNP- type bipolar transistor Q2 are made. The PNP-type transistor Q1 consists of the N+-type diffusion layer 16, the p-type well region 13, and the N-type well region 4; and does not have a gate part. The PNP-type bipolar transistor Q2 comprises the P+-type diffusion layer 17, the N-type well region 14, and the P-type substrate 11; and does not have a gate part.
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