Ultra-flat and ultra-smooth Cu surfaces produced by abrasive-free chemical-mechanical planarization/polishing using vacuum ultraviolet light

► An abrasive-free polishing method utilizing vacuum ultraviolet light was developed. ► Electrolyzed water was focused as polishing fluid for final polishing of rolled Cu. ► Electrolyzed oxidized water was unsuitable because projections were grown. ► Projections were removed in the case of using electrolyzed reduced water. ► An ultra-flat and ultra-smooth surface was achieved using this polishing setup.