An electrical conductor having a multilayer diffusion barrier of use in a resultant semiconductor device is presented. The electrical conductor line includes an insulation layer, a diffusion barrier, and a metal line. The insulation layer is formed on a semiconductor substrate and having 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 multi-layered structure made of TaN layer, an MoxOy layer and an Mo layer. The metal line is formed on the diffusion barrier to fill the metal line forming region of the insulation layer.