Rational utilization of the size and electronic effect of inhibitors enabling high polishing rate with minimum corrosion in copper chemical mechanical polishing

Abstract

Chemical mechanical polishing (CMP) relies on corrosion to remove excess materials, while also on corrosion inhibitors to ensure post-polished surface quality. The robust adsorption of inhibitors onto metal surfaces typically improves inhibition effectiveness but significantly reduces the polishing rate. In this study, we propose and validate a novel strategy that focuses on the utilization of large-sized physisorption-type inhibitors to address this inherent conflict. By incorporating disproportionated rosin (DR) as the inhibitor, the developed slurry facilely obtained a balance between polishing efficiency and quality for copper CMP. The inhibition mechanism of DR was elucidated through electrochemical characterization, adsorption isotherms, and reactive forcefield molecular dynamics (ReaxFF MD) simulations. The weak physisorption of the inhibitors facilitated their easy removal, resulting in minimal impact on the polishing rate. Additionally, the large-size structure of DR effectively hindered corrosive substances from reaching concave areas not under external force, thereby demonstrating superior inhibition efficacy. The adsorption mode of DR on copper was simultaneously determined through adsorption isotherms and ReaxFF MD simulations, marking the first instance of linking classic adsorption theory with MD simulations. The advantage of the ReaxFF MD simulations over classic MD simulations and density-functional-theory calculations for the metal-inhibitor adsorption systems was also discussed and demonstrated.