A semiconductor device may include a first film and a second film defining parts of a trench, a plug conductive film, a via, and a wiring in the trench. The trench may include a second sub-trench having a second width below a first sub-trench having a first width. The plug conductive film may extend from a first side of the first film to penetrate a bottom face of the trench. An uppermost face of the plug conducive film may be in the trench. The via may include an insulating liner between the plug conductive film and the first film. The uppermost face of the plug conductive film and at least a part of a side wall of the plug conductive film may be in contact with the wiring. An upper face of the insulating liner may be exposed by a bottom face of the second sub-trench.