Effect of organic amine in colloidal silica slurry on polishing-rate selectivity of copper to tantalum-nitride film in copper chemical mechanical planarization

Abstract

We investigated the effect of organic additives with amine functional group such as alanine and polyacrylamide (PAM) on the copper chemical mechanical planarization. We found that addition of alanine can significantly increase the copper polishing rate while slightly decrease the TaN polishing rate. We also concluded that small amount addition of PAM drastically suppress the TaN polishing rate. Both alanine and PAM can enhance the Cu-to-TaN removal selectivity. Finally, we also explained the interaction between organic additives and Cu/TaN film through the zetapotential.