Method of manufacturing semiconductor device

Abstract

A method of manufacturing a semiconductor device according to one aspect of the present invention comprises: forming a gate insulation film on a semiconductor substrate in which element separation regions are formed; depositing a gate lower layer material on the semiconductor substrate via the gate insulation film; depositing a gate upper layer material, which is composed of a material different from the gate lower layer material, on the gate lower layer material; forming a gate comprising a gate upper layer and a gate lower layer by selectively processing the gate upper layer material and the gate lower layer material; increasing the size of the gate upper layer in a horizontal direction with respect to the semiconductor substrate by carrying out a chemical reaction processing treatment to which the gate upper layer has a higher reaction speed than the gate lower layer; forming an impurity implantation region by implanting ions into the semiconductor substrate using the gate upper layer as a mask; and forming a source/drain diffusion layer from the impurity implantation region by carrying out a thermal diffusion treatment.