In a semiconductor device having an enlarged contact area between a contact structure and a substrate, the substrate may include a first region on which a conductive structure is arranged and a second region defining the first region. The first region may include a multi-faced polyhedral recess of which at least one of the sidewalls is slanted with respect to a surface of the substrate. An insulation layer may be formed on the substrate to a thickness that is sufficient to cover the conductive structure. The insulation layer has a contact hole that may be communicated with the recess. The active region of the substrate is exposed through the contact hole. A conductive pattern is positioned in the recess and the contact hole. Accordingly, the contact resistance at the active region of the substrate may be kept to a relatively low value even though the gap distances and line width of pattern lines are reduced.