US Patent 8986921 Lithographic material stack including a metal-compound hard mask

A lithographic material stack including a metal-compound hard mask layer is provided. The lithographic material stack includes a lower organic planarizing layer (OPL), a dielectric hard mask layer, and the metal-compound hard mask layer, an upper OPL, an optional anti-reflective coating (ARC) layer, and a photoresist layer. The metal-compound hard mask layer does not attenuate optical signals from lithographic alignment marks in underlying material layers, and can facilitate alignment between different levels in semiconductor manufacturing.