Inhibition Effect and Mechanism of 2-Mercaptopyrimidine on Cobalt-Based Copper Interconnects Chemical Mechanical Polishing: Combined Experimental and DFT Study

Abstract

Cobalt has been determined as a suitable barrier layer material for integrated circuits as the feature size continuous reduction to 14 nm. To protect the copper and cobalt surfaces from corrosion and obtain high copper and cobalt removal rate selectivity during cobalt-based copper interconnects chemical mechanical polishing process, selecting appropriate inhibitor in slurry is critical. In this paper, the inhibition effect and mechanism of 2-mercaptopyrimidine on copper/cobalt surfaces are studied combined experiments and density functional theory calculation. Experiments results reveal that 2-MP could increases the selectivity to 110.4, forms dense passivation film on the copper and cobalt surface to inhibits corrosion with high efficiency of 98% and 92%, and obtain ideal surface quality. Calculation results prove that the N-p and S-p orbitals of inhibitors hybridize with copper-d and cobalt-d orbital to form chemical bonds, adsorbing on metals surface vertically and parallelly. The mixed adsorption modes lead to form complete and dense passivation film. Such study provides better perspective into comprehending the corrosion protection of metal surfaces at the atomic level and clarifies the inhibition mechanism at the interface of metal-organic compounds.