There is provided a semiconductor device including an etching stop film which is placed disposed on a substrate; an interlayer insulating film which is disposed on the etching stop film; a trench which penetrates the interlayer insulating film and the etching stop film; a spacer which extends along side walls of the trench; a barrier film which extends along the spacer and a bottom surface of the trench; and a filling film which fills the trench on the barrier film. The trench includes a first trench and a second trench which are spaced apart from each other in a first direction and have different widths from each other in the first direction. A bottom surface of the second trench is placed disposed below a bottom surface of the first trench.