| 摘要 |
PURPOSE:To effectively protect the next step circuit by a method wherein a junction-type diode and an MIS type diode are formed in parallel on one semiconductor substrate and a desired breakdown voltage is set by selecting the channel length of the MIS type diode. CONSTITUTION:A P type well region 2 is formed by diffusion in an N type Si substrate 1 and N<+> type regions 3 and 7 are provided in the region 2 and input is connected to the region 3 and a junction-type diode is composed between the regions 3 and 2. And a gate electrode 6 is mounted between the regions 3 and 7 through a thin gate oxide film 8 and an MIS type diode forming the regions 3 and 7 as a drain region and a source region respectively is composed. Next, each P<+> type region 4 is formed by diffusion at the outside of the regions 3 and 7 by locating the regions 4 in the region 2 through oxide films 5 and the regions 4 are connected to a low- potential source and the region 7 and the gate 6 are connected to the low-potential source. In this composition, with a desired breakdown voltage set by selecting the channel length of the MIS type diode, and increase in the breakdown voltage of a protective circuit connected to the MIS type diode is permitted. |
