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 Å/min. Various analytical results, including electrochemical, X-ray photoelectron spectroscopy, Raman experiments, atomic force microscopy and confocal microscope data, revealed that the RR of Ru can be improved by reducing electrostatic repulsion and also by forming Ru-DTPA complexes.

Chemical mechanical polishing is a key step in semiconductor technology because it is crucial to produce a defect-free and flat enough surface for further processing of microelectronic devices. Silicon (Si) wafer is widely used in integrated circuit (IC) devices, high-density information storage devices, and other advanced applications. In this paper, the effect of different pH and three ethanolamines (MEA, DEA, TEA) on the removal rate of Si was studied. The results show that the removal rate increased first and then decreased with increasing pH. Among the three ethanolamines, the effect of the removal rate is MEA>DEA>TEA. It may be related to the denser passivation film formed on the Si surface by increased hydroxyl groups in ethanolamines. The removal rate first increased and then decreased with the concentration of MEA increased and reached the peak value when the MEA concentration was 0.15 wt%. The changing trend of the removal rate is due to the Si-N bond being generated on the polished Si surface by MEA and the ionization properties of MEA, which are indicated through the X-ray photoelectron spectroscopy and the Zeta potential measurements. Si surfaces with low surface roughness and ultra-smooth with increased MEA concentration were obtained.