As technology is scaled down to 5 nm or even smaller, ruthenium (Ru) will most likely be chosen as the next generation barrier material for copper interconnects in integrated circuits (ICs). Recently, the higher removal rate of Ru barrier materials in chemical mechanical polishing (CMP) has become a major issue. In this paper, diethylene triaminepentaacetic acid pentapotassium salt (DTPA-5K) was introduced as a new complexing agent in a hydrogen peroxide (H2O2)-based alkaline slurry with the goal of increasing the Ru removal rate (RR) during chemical mechanical polishing (CMP). The synergy of H2O2 and DTPA-5K significantly improved the RR of Ru to 412 angstrom min(-1). Various analytical results, including electrochemical, X-ray photoelectron spectroscopy (XPS), Raman experiments, atomic force microscopy (AFM) and confocal microscope data, revealed that the RR of Ru can be improved by reducing electrostatic repulsion and also by forming Ru-DTPA complexes.
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