| 摘要 |
PROBLEM TO BE SOLVED: To obtain transistors with different breakdown voltages each without causing an increase in size of the transistor, while added processes for making each breakdown voltage of transistors different mutually is reduced to a minimum. SOLUTION: The bipolar structure consisting of N+ source drain regions 15 and 15 and a P well 7 is the same at NMOS transistors 3n, 5n. The bipolar structure consisting of P+ source drain regions 19, 19 and an N well 9 is the same at PMOS transistors 3p, 5p. The protective NMOS transistor 5n and an internal PMOS transistor 3p are covered by silicon nitride film 23, while the internal NMOS transistor 3n and the protective PMOS transistor 5p are not covered by silicon nitride film 23. The breakdown voltage of the protective NMOS transistor 5n is lower than that of the inner NMOS transistor 3n, while the breakdown voltage of the protective PMOS transistor 5p is lower than that of the inner PMOS transistor 3p. COPYRIGHT: (C)2008,JPO&INPIT
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