Abstract: An etch stop layer is formed on a lower wiring. An interlayer insulating film covers the lower wiring and the etch stop layer. A via exposes an upper surface of the etch stop layer, in the interlayer insulating film. A first filler is formed in the via. The first filler is etched to a first filler pattern. A second filler is formed on the first filler pattern and is etched to a second filler pattern. A trench is formed by etching the interlayer insulating film. The first and second filler patterns are etched during the forming of the trench to form a residual filler pattern. The residual filler pattern and the etch stop layer are removed and a wiring structure is formed electrically connected to the lower wiring. The via includes lower and upper portions and the trench includes the upper portion of the via.