Effect of glycine and hydrogen peroxide on chemical–mechanical planarization of copper

Abstract

Chemical–mechanical planarization (CMP) of copper is a vital process to produce sub-micron range and multilevel metallization to meet the demands of the current interconnect technology. The present investigation was focussed to understand the oxidation, dissolution and modification of Cu surface using hydrogen peroxide as oxidizer and glycine as inhibitor during Cu-CMP employing electrochemistry as well as dynamic and static removal rate measurements. Surface modification of copper was investigated in detail using X-ray photoelectron spectroscopy to understand the interaction of Cu–H 2O 2–glycine complex formation during CMP. Atomic force microscopy was employed to reveal any change in surface morphology during the CMP process. In the presence of 0.1 M glycine, copper removal rate was found to be high in the solution containing 2.5% H 2O 2 at pH 4 because of Cu 2+–glycine complexation reaction. In the absence of glycine, the removal rate of copper decreased with increasing H 2O 2 concentration due to the formation of a less soluble copper oxide film. The present investigation helped understanding the mechanism of Cu surface alteration in presence of oxidizers and glycine for formulation of highly effective CMP-slurry.