An example embodiment relates to a method for making a mask layer. The method may include providing a patterned layer on a substrate, the patterned layer including at least a first set of lines of an organic material of a first nature, the lines having a line height, a first line width roughness, and being separated either by voids or by a material of a second nature. The method may further include infiltrating at least a top portion of the first set of lines with a metal or ceramic material. The method may further include removing the organic material by oxidative plasma etching, thereby forming a second set of lines of metal or ceramic material on the substrate, the second set of lines having a second line width roughness, smaller than the first line width roughness.