Semiconductor device and manufacturing method thereof

Abstract

A method of manufacturing a semiconductor device, including forming a gate insulating film on a P type semiconductor layer, forming on the gate insulating film a gate electrode having slits at, at least an end thereof on the drain electrode forming predeterminate side, selectively implanting an N type impurity into the P type semiconductor layer with the gate electrode as a mask, effecting heat treatment to activate the impurity and integrating impurity regions in which the impurity is implanted in the slits and portions outside the gate electrode, by transverse direction thereby to form a pair of N type low-density diffused layers that overlap, at least, on the drain electrode side of the gate electrode, and forming a pair of N type high-density diffused layers spaced away from the gate electrode.