In a method of fabricating a semiconductor device by selectively forming a diffusion barrier layer, and a semiconductor device fabricated thereby, a conductive pattern and an insulating layer, which covers the conductive pattern, are formed on a semiconductor substrate. The insulating layer is patterned, thereby forming an opening for exposing at least a portion of the conductive pattern. Then, a diffusion barrier layer is formed on the semiconductor substrate having the opening, using a selective deposition technique. The diffusion barrier layer is formed to a thickness that is less on the exposed conductive pattern than the thickness of the diffusion barrier layer on the insulating layer exposed inside the opening. Then, the diffusion barrier layer is etched, thereby forming a recessed diffusion barrier layer. In this manner, metal atoms are prevented from being diffused from a metal plug filling the opening or a metal interconnect to the insulating layer.