The present invention relates to semiconductor devices and a method of fabricating the same. According to a method of manufacturing semiconductor devices, there is first provided a semiconductor substrate in which a first pre-metal dielectric layer including trenches is formed. A diffusion barrier layer is formed on the entire surface including the trenches. A metal layer is formed on the diffusion barrier layer including the trenches, thereby gap-filling the trenches. A polish etching process is performed on the metal layer and the diffusion barrier layer so that the diffusion barrier layer and the metal layer remain within the trenches. An etching process of lowering a height of the metal layer is performed in order to increase a distance between metal lines. A capping layer is formed on the entire surface including exposed sidewalls of the first pre-metal dielectric layer. A second pre-metal dielectric layer is formed over the capping layer.