A method of forming a multi-layer stack over a low-k dielectric layer is disclosed, wherein the multi-layer stack provides an improved anti-reflective effect and an enhanced protection of the underlying low-k dielectric material during the chemical mechanical polishing process. The multi-layer stack includes silicon dioxide based sub-layers, which may be formed in a highly efficient, non-expensive plasma enhanced deposition method, wherein the optical characteristics may be adjusted by varying a ratio of silane and nitrogen oxide during the deposition.