JPS6484667A - Insulated-gate transistor - Google Patents

Abstract

PURPOSE:To keep a transistor of this design from decreasing in reliability even if it is micronized by a method wherein a high concentrated region of the same conductiv ity as a substrate is provided in a low concentrated region in such a manner that it is formed below the surface, and a gate electrode is formed thereon. CONSTITUTION:A p<+> region 105 is supplied with VSUB, where VSUB is impressed on a substrate through a p<+> region 205 which is positioned under a field oxide film 209 and serves as a channel stopper. When a voltage VG is supplied to an n<+> polySi gate electrode 106, where the voltage VG is large enough to make a channel section of a MOSFET reverse, an n<-> low concentrated drain region 104' is made to be included in the channel section and a current is made to flow through the surface from a source 102 to a drain 103 as a drain voltage VD is made to increase. When the drain voltage VD increase further, a depletion layer is made to expand at a junction part between the p<+> region 105 and the n<-> regions 104 and 104' and a current passage transfers gradually from the surface (upper part ot the p<+> region) to an inner part (lower part of it). Therefore, the generation of hot carriers takes place at an inner part separate from a gate oxide film, and thus a transistor of this design can be prevented from decreasing in reliabilty.