Method of manufacturing semiconductor device of dual-gate construction, and semiconductor device manufactured thereby including forming a region of over-lapping n-type and p-type impurities with lower resistance

Abstract

There is described a method of manufacturing a semiconductor device of dual-gate construction, which method prevents occurrence of a highly-resistant local area in a gate electrode of dual-gate construction. A polysilicon layer which is to become a conductive layer of a gate electrode of dual-gate construction is formed on an isolation oxide film. N-type impurities are implanted into an n-type implantation region of the polysilicon film while a photoresist film is taken as a mask. P-type impurities are implanted into a p-type impurity region of the polysilicon film 3 while another photoresist film is taken as a mask. Implantation of n-type impurities and implantation of p-type impurities are performed such that an overlapping area to be doped with these impurities in an overlapping manner is inevitably formed.