US Patent 7348676 Semiconductor device having a metal wiring structure

After an insulation layer is formed on a substrate, a contact hole is formed through the insulation layer. A recessed plug is formed to partially fill up the contact hole. The recessed plug has a height substantially smaller than a depth of the contact hole. A metal wiring structure is formed on the recessed plug and on the insulation layer. A lower portion of the metal wiring structure, formed within the contact hole, prevents damage to the recessed plug during an etching process for forming the metal wiring structure. Therefore, the recessed plug may be formed without damage thereof even if an alignment error occurs between an etching mask and the recessed plug during metal wiring structure formation.