Disclosed is a semiconductor device including a substrate, a first interlayer dielectric layer on the substrate, a plurality of first vias in the first interlayer dielectric layer, a second interlayer dielectric layer on the first interlayer dielectric layer, and a first power line and a first lower line in the second interlayer dielectric layer that are electrically connected to respective ones of the first vias. A first width in a first direction of the first power line is greater than a second width in the first direction of the first lower line. The first power line includes a first metallic material. The first lower line includes a second metallic material. The first vias includes a third metallic material. The first, second, and third metallic materials are different from each other.