A method for fabricating a single-damascene opening is described. The method includes providing a substrate having a conductive line formed therein. A barrier layer, a dielectric layer, a metal hard mask layer, a silicon oxynitride layer, a bottom antireflection layer and a patterned photoresist layer are sequentially formed on the substrate. The bottom antireflection layer, the silicon oxynitride layer and the metal hard mask layer that are not covered by the patterned photoresist layer are removed in a single process step, until a part of the surface of the dielectric layer is exposed. Thereafter, the patterned photoresist layer and the bottom antireflection layer are removed. Further using the silicon oxynitride layer and the metal hard mask layer as a mask, a portion of the dielectric layer and a portion of the barrier layer are removed to form a damascene opening that exposes the surface of the conductive line.
