| 摘要 |
PURPOSE:To improve the electrostatic breakdown voltage of an input/output circuit. CONSTITUTION:When electrostatic protection against an output circuit is performed, a third n-type diffused region 48 is provided in addition to a first n-type diffused region 13 and a second n-type diffused region 14. The third n-type diffused region 48 is used as the drain of a thick-film field transistor 49 in (C). Thus, two field transistors 36 and 49 are connected in parallel with respect to a bonding pad 29. Both sources of the transistors are connected to a reference potential. In this way, electrostatic surge current, which are applied on the bonding pad 29, flow in parallel between the drains and the sources of two field transistors 36 and 49 and discharged to the reference potential. Thus, the protection of the inner output circuit is accomplished. &Z11: p-type substrate, a: to reference potential, b: to output gate, c: (X-X' cross section) |
