Understanding the adsorption mechanism of benzotriazole and its derivatives as effective corrosion inhibitors for cobalt in chemical mechanical polishing

Abstract

Cobalt is emerging as the next-generation interconnect material to replace copper for integrated circuit sub-10 nm technology nodes. Due to its susceptibility to corrosion, identifying effective corrosion inhibitors for Co during the chemical mechanical polishing (CMP) is crucial. In this study, theoretical computations and experimental approaches were employed to investigate the corrosion inhibition effects of benzotriazole (BTA) and its derivatives—methylbenzotriazole (TTA) and 5-carboxybenzotriazole—on Co surfaces. Quantum chemical calculations and molecular dynamics simulations were used to reveal the corrosion mechanism at the atomic level. The computational findings were further validated by electrochemical experiments. Among the inhibitors studied, TTA exhibited the highest adsorption affinity for the Co surface, achieving an inhibition efficiency of up to 91.71 %. This is attributed to the formation of a dense protective layer on the Co surface through both physical adsorption via intermolecular forces and chemical adsorption via charge transfer. CMP experiments demonstrated that all three inhibitors significantly reduce the material removal rate (MRR) of Co. Notably, when the TTA concentration reaches 9 mM, the MRR is reduced to 132.64 nm/min, meeting the requirements for Co bulk polishing. These findings suggest that TTA is a highly promising Co corrosion inhibitor for slurry development in CMP processes.