Method of manufacturing an insulated-gate semicustom integrated circuit.

摘要

Incorporated in a MOS semicustom integrated circuit are pull-up and pull-down MOS transistors (11, 12) adapted for pulling up or down the potential of a signal line (10) connecting a protection circuit (6) with an internal circuit (7) to be protected from electrostatic breakdown. The MOS transistors have their drains connected together to the signal line and their sources connected to a pull-up power supply node (VDD) or pull-down power supply node (VSS) as required. The MOS transistor acts as a pull-up or pull-down transistor where its source is connected to the pull-up or pull-down power supply node by master slice wiring, and its drain junction acts as a protective diode where its source remained open. Thus, owing to the protection functions of the drain junction and diodes in the protection circuit the electrostatic breakdown strength of the internal circuit can be increased without increase in the occupied area of the protection circuit in the integrated circuit.