Abstract: A semiconductor device having a protective transistor for protecting an internal circuit from an excess voltage applied to an input terminal is disclosed. The protective transistor includes first and second channel regions coupled in series each other and formed between source and drain regions. A portion of a field insulating layer is provided on the first channel region as a gate insulating film, and the drain region is separated from the portion of the field insulating layer by the second channel region.

Abstract: An improved protective device for an integrated circuit which can be fabricated on a reduced area is disclosed. The protective device comprises a punch-through type transistor connected between an input pad and a reference voltage terminal and made of first and second spaced-apart impurity regions, and a resistor region extending from a part of outer side of the first impurity region and running under the input pad.

Abstract: For decreasing a leakage current, there is disclosed a protective network fabricated on a semiconductor substrate for preventing a protected node from a destruction comprising, a semiconductor substrate of a first conductivity type, an insulating film overlying the semiconductor substrate, a first impurity region of a second conductivity type formed in the semiconductor substrate and providing a signal path with a relatively large resistance value electrically connected at a contact portion thereof to the protected node, the signal path having an upstream portion and a downstream portion providing between the contact portion and the upstream side portion, a second impurity region of the second conductivity type formed in the semiconductor substrate and electrically connected to a constant voltage source, a separating region defined in the semiconductor substrate and intervening between a part of the first impurity region and the second impurity region for causing the part of the first impurity region to be sp