A metal wiring layer and a method of fabricating the metal wiring layer are provided. The method includes forming a dielectric layer on a substrate, forming a plurality of dielectric layer patterns and holes therein on the substrate by etching part of the dielectric layer, with a cross sectional area of the holes in the dielectric layer patterns decreasing with increasing distance away from the substrate and the holes exposing the substrate, forming a trench by etching a portion of the substrate exposed through the holes in the dielectric layer patterns, and forming a metal layer which fills the trench and the holes in the dielectric layer patterns. Thus, it is possible to prevent the occurrence of an edge build-up phenomenon by forming a metal layer in a plurality of holes in the dielectric layer patterns having a cross sectional area decreasing with increasing distance away from the substrate. Therefore, it is possible to prevent the transmittance of a liquid crystal layer from decreasing due to a failure to properly fill liquid crystal molecules in the liquid crystal layer, and thus to increase the quality of display.