An integrated circuit device includes a substrate including a trench therein and a conductive plug wire pattern in the trench. The conductive plug wire pattern includes a recessed portion that exposes portions of opposing sidewalls of the trench, and an integral plug portion that protrudes from a surface of the recessed portion to provide an electrical connection to at least one other conductive wire pattern on a different level of metallization. A surface of the plug portion may protrude to a substantially same level as a surface of the substrate adjacent to and outside the trench, and the surface of the recessed portion may be below the surface of the substrate outside the trench. Related fabrication methods are also discussed.