ins when burying the interconnection grooves and the contact holes with copper. [0207] Next, as shown in FIG. 2B, an interconnection layer 105 made of copper is formed on the barrier metal film 103 to a thickness of for example about 1200 nm to 1600 nm so as to bury the contact holes CH and the interconnection grooves M. The interconnection layer 105 is preferably formed by electroplating or elect