Effects of electric potential on chemical-mechanical polishing of copper

The effect of electric potential on the dissolution and polishing behavior of copper in acidic and alkaline media was investigated. The electromechanical polishing mechanism of copper is discussed based on removal rate of copper, pH of slurries, and surface morphology of polished copper. The most interesting phenomenon occurred in chemical-mechanical polishing (CMP) of copper with applied direct current (DC) voltage is the variation of pH during polishing. The dissolution experiments indicated that an acidic agent might have more hydrogen reduced with higher DC potential. The results demonstrated that the application of DC voltage is beneficial to improve planarization of copper polishing in an alkaline slurry.