A semiconductor device includes an insulating interlayer over a substrate in a first region, the insulating layer including contact holes exposing a portion of a surface of the substrate, and contact plugs in the contact holes. The contact plugs include a stacked structure of a first barrier metal layer pattern and a first metal layer pattern. The semiconductor device also includes second metal layer patterns directly contacting with the contact plugs and an upper surface of the insulating interlayer. The second metal layer pattern consists is a metal material layer.