Relative roles of H2O2 and glycine in CMP of copper studied with impedance spectroscopy

Peroxide-based slurries are commonly used in chemical mechanical polishing (CMP) of copper. When glycine is included in such a slurry, the planarization efficiency of Cu-CMP is considerably enhanced. In this work, we investigate the selective and collective chemical effects of H2O2 and glycine that promote favorable conditions for CMP of Cu. A number of surface reactions contribute to metal removal in this system by forming soluble surface complexes that can be easily removed by mechanical abrasion. We use Fourier transform electrochemical impedance spectroscopy (FT-EIS) to probe these reactions. The FT-EIS results provide detailed circuit models of the chemically active Cu interface. Simple analyses of the voltage-dependent kinetic (circuit) parameters of these models allow us to propose and examine the reaction steps for Cu-glycine complex formation on oxidized Cu. (C) 2004, The Electrochemical Society.