Semiconductor devices having a copper line layer and methods for manufacturing the same are disclosed. An illustrated semiconductor device comprises a damascene insulating layer having a contact hole, a barrier metal layer including a first ruthenium layer, a ruthenium oxide layer and a second ruthenium layer, a seed copper layer formed on the barrier metal layer, and a copper line layer made of a Cu—Ag—Au solid solution. A disclosed example method of manufacturing a semiconductor device reduces and/or prevents contact characteristic degradation of the barrier metal layer with the silicon substrate or the damascene insulating layer. In addition, by forming the copper line layer made of the Cu—Ag—Au solid solution, long term device reliability may be improved.