Abstract: A semiconductor device is provided. The semiconductor device includes: a first interlayer insulating film defining a lower wiring trench; a lower wiring structure including a first lower barrier film which extends along sidewalls of the lower wiring trench, and a lower filling film which is on the first lower barrier film; a second interlayer insulating film on the first interlayer insulating film, the second interlayer insulating film defining an upper wiring trench which exposes at least part of the lower wiring structure; and an upper wiring structure provided in the upper wiring trench and connected to the lower wiring structure. An upper surface of the first lower barrier film is closer to a bottom surface of the lower wiring trench than each of an upper surface of the first interlayer insulating film and an upper surface the lower filling film. The upper surface of the first lower barrier film is concave.