A semiconductor device includes a first interlayer insulating film disposed on a substrate and having a first trench. A first lower conductive pattern fills the first trench and includes first and second valley areas that are spaced apart from each other in a first direction parallel to an upper surface of the substrate. The first and second valley areas are recessed toward the substrate. A second interlayer insulating film is disposed on the first interlayer insulating film and includes a second trench that exposes at least a portion of the first lower conductive pattern. An upper conductive pattern fills the second trench and includes an upper barrier film and an upper filling film disposed on the upper barrier film. The upper conductive pattern at least partially fills the first valley area.