The chemical mechanical planarization (CMP) of copper-based structures is typically carried out with slurries that contain an oxidant, a complexant, and a corrosion inhibitor. The dissolution and passivation of copper are strongly influenced by the pH and the redox potential of the slurry systems. In this paper, potential-pH diagrams for copper in aqueous systems containing various organic compounds and oxidants of interest to copper CMP are presented. The stability region of copper complexes under varying copper and ligand concentrations and the effect that they may have on copper removal during CMP are discussed. Experimental values of redox potentials in some of the chemical systems are included in the diagrams. In cases where the free energy of formation of organic ligands was not available in the literature, values were estimated using the group contribution method. © 2002 The Electrochemical Society. All rights reserved.

Chemical mechanical planarization ͑CMP͒ has emerged as the most viable method to planarize copper thin films during fabrication of integrated circuits. The final stage of copper CMP requires the simultaneous polishing of copper and the barrier metal, where the metals are prone to galvanic corrosion due to exposure to slurry. In this study, the extent of galvanic corrosion between copper and tantalum was estimated using electrochemical polarization measurements. A novel setup was designed to make direct measurement of the galvanic current between copper and tantalum and was successfully used to measure galvanic current in two different chemical systems. Galvanic corrosion current values obtained from polarization and direct measurements are compared and their implications during barrier polishing are discussed.Chemical mechanical planarization or polishing ͑CMP͒ of copper is now routinely used for the formation of copper interconnect structures. In a CMP process, planarization of metal and dielectric areas is achieved by polishing a wafer with uneven topography on a polymeric pad held by a rotating platen using a colloidal slurry consisting of submicrometer-sized abrasive particles. Chemicals in the slurry, depending on their nature, play the role of oxidizer, slurry stabilizer, metal ion complexant, or corrosion inhibitor. In the abrasive-free polishing ͑AFP͒ process, the polishing medium consists of only chemicals and no particles.

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