The role of glycine in the chemical mechanical planarization of copper

Chemical mechanical polishing (CMP) is an essential process in the production of integrated circuits containing copper interconnects. The role of glycine in reactive slurries representative of those that might be used in copper CMP was studied with the aim of improving our understanding of the mechanisms at play. The electrochemical processes involved in the oxidative dissolution of copper were investigated by potentiodynamic polarization studies. To delineate the specific effect of glycine on the dissolution and polishing of copper, electrochemical tests were conducted in aqueous media with and without glycine. Experimentally measured polarization curves agreed well with potential-pH diagrams for the copper-water and copper-water-glycine systems. In situ electrochemical polarization experiments and open-circuit potential measurements were then conducted during polishing using slurries containing either no glycine or 10(-2) M glycine. These tests indicated that glycine curtails the formation of copper oxide films during polishing and hence may improve the CMP process by controlling the oxide thickness. (C) 2002 The Electrochemical Society.