| 摘要 |
PURPOSE:To protect a gate oxide film for a MIS transistor stably from input surge voltage by gradually reducing channel length between source and drain regions in a MIS transistor for protection from the input pad side. CONSTITUTION:A polysilicon resistor 2 and a MIS transistor 4 for protection are formed between an input pad 1 shaped by Al and a gate for a MIS transistor 11. With the MIS transistor 4 for protection, source-drain regions 5, 6 shown in dotted lines are separated and shaped, and a taper 8 is formed to a section faced oppositely to a channel region 7 in the source region. Consequently, channel length L is reduced gradually from the side connected to the polysilicon layer 2. Accordingly, input surge voltage can be passed through a ground uniformly in the transistor 4 for protection, thus preventing the breakdown of a gate oxide film for the MIS transistor 11. |
