Electrochemical effects in the chemical-mechanical polishing of copper for integrated circuits

Chemical-mechanical polishing of copper in ammonia based solutions has been studied using electrochemical techniques such as electrochemical potential, I linear polarization resistance,: and potentiodynamic polarization. A copper rotating disk electrode was used to simulate polishing conditions. Measurements made on sputter-coated wafers during polishing were used for comparison. The dissolution of copper is limited by transport of Cu(NH3)(2)(+) away from the surface, and the removal rate of copper during polishing is controlled in the solution by the formation of copper ammine complexes.