The present disclosure provides a method for defining patterns for conductive paths in a dielectric layer. An example method includes forming a mask layer and forming a set of mandrels, each mandrel having a pair of side wall spacers. The method also includes etching the mask layer to form a first set of trenches in the mask layer. The method further includes covering the set of mandrels with a metal oxide planarization layer, the metal oxide planarization layer filling the first set of trenches. The method also includes etching back the metal oxide planarization layer. The method also includes removing the set of mandrels by etching, thereby forming trenches in the metal oxide planarization layer, the trenches extending between the pairs of side wall spacers. The method also includes etching the mask layer to form a second set of trenches in the mask layer.