| 摘要 |
PURPOSE:To prevent the breakdown of a semiconductor IC due to static electricity, by utilizing the breakdown of a semi-insulating substrate sandwiched by one conductive type semiconductor regions which are closely contacted each other. CONSTITUTION:Semiconductor regions 2 and 3 of n<+> type are formed in the GaAs semi-insulating substrate 1, and a Zener diode is formed between the substrate 1. Semiconductor regions 10 and 17 of n<+> type serving as a drain and a source, and an n<-> type semiconductor region 14 serving as a gate are formed in the substrate, and a metallic semiconductor (MES)-FET is formed of regions 10, 14 and 17. In this cnstitution, when the surge due to static electricity is impressed on an external input terminal 4, the voltage of a node N2 increases, and, when it exceeds the reverse breakdown voltage of the Zener diode in an equivalent circuit, breakdown generates between the regions 2 and 3. As a result, the voltage of a node N3 increases, and, when it exceeds the threshold voltage of the MES-FET 9, the FET 9 turns into an ''ON'' state and will drop the voltage of a node N4 down to the earth voltage. Therefore, high potential is prevented from being transmitted into the IC. |
