Patent ID: 8729618

Claim:
A semiconductor device comprising: a semiconductor substrate; a first impurity diffusion region provided in the semiconductor substrate; a second impurity diffusion region provided in the semiconductor substrate and adjacent to the first impurity diffusion region; a first contact plug including a first epitaxial layer and a second epitaxial layer provided on the first impurity diffusion region in this order, where the second epitaxial layer includes a bottom surface area and a top surface area that is smaller than the bottom surface area, a second contact plug including a third epitaxial layer and a fourth epitaxial layer provided on the second impurity diffusion region in this order and adjacent to the first contact plug, where the fourth epitaxial layer includes a bottom surface area and a top surface area that is smaller than the bottom surface area, so that the first and second epitaxial layers are provided adjacent to the third and fourth epitaxial layers without any intervening conductive layer.