| 摘要 |
PURPOSE: A stacked mosfet protection circuit is provided to ensure the TDDB and HCI reliability of a semiconductor device and prevent a gate oxide film from being destroyed. CONSTITUTION: For the purpose of preventing breakdown of a gate insulating film of a MOSFET(Q1) constituting a stacked protection circuit(Q1,Q2) caused by application of a surge voltage between the gate and the drain of the MOSFET(Q1), a single or a plurality of diodes or a MOSFET switch is connected between the gate and the drain of the MOSFET(Q1) for absorbing the surge voltage. The particular construction permits obtaining a large surge tolerance against the surge voltage entering through, for example, the external power source pad, making it possible to form a protection circuit(Q1,Q2) used in I/O's tolerant to other power sources having an appropriate snap-back voltage against the external surge in assuring the reliability of the semiconductor device.
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