The combinatorial effect of complexing agent and inhibitor on chemical-mechanical planarization of copper

Chemical-mechanical planarization (CMP) is a vital process for the fabrication of advanced copper multilevel interconnects schemes. The focus of this investigation was to understand the oxidation, dissolution and surface modification characteristics of Cu. in slurries with varying pH. Hydrogen peroxide was used as the oxidizer, glycine as complexing agent and 3-amino-triazol (ATA) as inhibitor in the slurry. The electrochemical process involved in the oxidative dissolution of copper was investigated by potentiodynamic polarization studies. X-ray photoelectron spectroscopy was used to investigate the surface modification of copper and understand the interaction between CU-H2O2-glycine-ATA during CMP. In the absence of glycine and ATA, copper removal rate was found to be high in the slurry with 5% H2O2 at pH 2. The removal rate then decreased and reached the minimum at pH 6 and started to increase in alkaline conditions. With the addition of 0.01 M glycine, the removal rates of copper were lowered in acidic slurries, but increased significantly in alkaline slurries. The addition of ATA lowered copper removal rates, however, better surface planarity was achieved. The present investigation provides an insight to the mechanism of Cu removal in the presence of oxidizer, complexing agent and inhibitor. (C) 2003 Elsevier B.V. All rights reserved.