A semiconductor device includes first and second conductor patterns embedded in a first interlayer insulation film and a third conductor pattern embedded in a second interlayer insulation film, the third conductor pattern including a main part and an extension part, the extension part being electrically connected to the first conductor pattern by a first via-plug, the extension part having a branched pattern closer to the main part compared with the first conductor pattern, the branched pattern making a contact with the second conductor pattern via a second via-plug, each of the main part, extension part including the branched pattern, first via-plug and second via-plug forming a damascene structure.