A metal line having a MoxSiy/Mo diffusion barrier of a semiconductor device and corresponding methods of fabricating the same are presented. The metal line includes an insulation layer, a diffusion barrier, and a metal layer. The insulation layer is formed on a semiconductor substrate and has a metal line forming region. The diffusion barrier is formed on a surface of the metal line forming region of the insulation layer and has a stack structure composed of a MoxSiy layer and a Mo layer. The metal layer is formed on the diffusion barrier which fills in the metal line forming region of the insulation layer.