A method for fabricating a semiconductor device having a metal wiring is provided. The method includes: forming an inter-metal dielectric (IMD) layer on the semiconductor substrate having a first metal wiring formed therein, the IMD layer including a first IMD layer and a second IMD layer; forming a via hole in the IMD layer to expose the first metal wiring; forming an ion barrier layer on sidewalls of the via hole; forming a diffusion barrier layer on the semiconductor substrate, on which the ion barrier layer has been formed; forming a metal layer on the semiconductor substrate in the via hole; and forming a second metal wiring on the semiconductor substrate, the second metal wiring contacting the metal layer in the via hole.