Semiconductor device and method of manufacture thereof

A manufacturing method of semiconductor device provided with a contact plug electrically connected to an impurity diffusion region in the surface part of a semiconductor layer via a metal silicide layer, comprising the steps of:

• forming an impurity diffusion region in the surface part of a semiconductor layer;
• forming a metal silicide layer in the surface part of the impurity diffusion region;
• forming an interlayer insulating film on the semiconductor layer formed with the metal silicide layer;
• forming a mask pattern having an opening at a contact plug formation position on the interlayer insulating film;
• forming a through hole in the interlayer insulating film by etching via the mask pattern;
• forming a recess in the metal silicide layer by etching via the through hole;
• expanding the diameter of the through hole;
• and
• forming a contact plug by filling a conductor into the through hole with the expanded diameter.