A semiconductor device is fabricated by forming first holes arranged along a first direction on an etch-target layer, forming dielectric patterns in the first holes, conformally forming a barrier layer on the dielectric patterns, forming a sacrificial layer on the barrier layer to define a first void, partially removing the sacrificial layer to expose the first void, anisotropically etching the barrier layer to form second holes below the first void, and etching portions of the etch-target layer located below the first and second holes to form contact holes. The first void may be formed on a first gap region confined by at least three of the dielectric patterns disposed adjacent to each other, and the sacrificial layer may include a material having a low conformality.