Abstract: A transistor-type protection device includes: a semiconductor substrate; a well including a first-conductivity-type semiconductor formed in the semiconductor substrate; a source region including a second-conductivity-type semiconductor formed in the well; a gate electrode formed above the well via a gate insulating film at one side of the source region; a drain region including the second-conductivity-type semiconductor formed within the well apart at one side of the gate electrode; and a resistive breakdown region including a second-conductivity-type semiconductor region in contact with the drain region at a predetermined distance apart from the well part immediately below the gate electrode, wherein a metallurgical junction form and a impurity concentration profile of the resistive breakdown region are determined so that a region not depleted at application of a drain bias when junction breakdown occurs in the drain region or the resistive breakdown region may remain in the resistive breakdown region.

Abstract: Disclosed herein is a semiconductor integrated circuit including a protected circuit; and a protection element formed on the same semiconductor substrate as the protected circuit and adapted to protect the protected circuit, wherein the protection element includes two diodes having their anodes connected together to form a floating node and two cathodes connected to the protected circuit, the two diodes are formed in a well-in-well structure on the semiconductor substrate, and the well-in-well structure includes a P-type well forming the floating gate, an N-type well which surrounds the surfaces of the P-type well other than that on the front side of the substrate with the deep portion side of the substrate so as to form the cathode of one of the diodes, and a first N-type region formed in the P-type well so as to form the cathode of the other diode.

Abstract: Disclosed herein is a semiconductor integrated circuit including a protected circuit; and a protection element formed on the same semiconductor substrate as the protected circuit and adapted to protect the protected circuit, wherein the protection element includes two diodes having their anodes connected together to form a floating node and two cathodes connected to the protected circuit, the two diodes are formed in a well-in-well structure on the semiconductor substrate, and the well-in-well structure includes a P-type well forming the floating gate, an N-type well which surrounds the surfaces of the P-type well other than that on the front side of the substrate with the deep portion side of the substrate so as to form the cathode of one of the diodes, and a first N-type region formed in the P-type well so as to form the cathode of the other diode.

Abstract: A transistor-type protection device includes: a semiconductor substrate; a well including a first-conductivity-type semiconductor formed in the semiconductor substrate; a source region including a second-conductivity-type semiconductor formed in the well; a gate electrode formed above the well via a gate insulating film at one side of the source region; a drain region including the second-conductivity-type semiconductor formed within the well apart at one side of the gate electrode; and a resistive breakdown region including a second-conductivity-type semiconductor region in contact with the drain region at a predetermined distance apart from the well part immediately below the gate electrode, wherein a metallurgical junction form and a impurity concentration profile of the resistive breakdown region are determined so that a region not depleted at application of a drain bias when junction breakdown occurs in the drain region or the resistive breakdown region may remain in the resistive breakdown region.