Competitive effect between corrosion inhibitors in copper chemical mechanical polishing

Abstract

Corrosion inhibitors are critical to realizing local and global planarization in copper chemical mechanical polishing (CMP). It is necessary to explore the interaction between components of composite corrosion inhibitors. This study reported a type of composite corrosion inhibitors of 1,2,4-triazole (TAZ) and 5-methyl-benzotriazole (5-MBTA) having a competitive effect between TAZ and 5-MBTA, different from the conventional synergistic effect. It is revealed that after adding either TAZ or 5-MBTA or their combination, the copper surface quality can be improved, while the copper material removal rate (MRR) ranks: TAZ > TAZ + 5-MBTA > 5-MBTA. For the competitive effect, TAZ and 5-MBTA can be co-adsorbed on the copper surface. Meanwhile, the electrochemical results indicate that the corrosion inhibition effect can rank: 5-MBTA > TAZ + 5-MBTA > TAZ, implying that TAZ and 5-MBTA may compete for the adsorption sites. The competitive effect may root in the different molecular structures, presumably the benzene ring. According to the corrosion wear mechanism of copper CMP, the stronger the corrosion inhibition effect, the lower the MRR. Therefore, the MRR of the composite corrosion inhibitors is between TAZ and 5-MBTA. The finding provides an enhanced understanding of composite corrosion inhibitors in the copper CMP.