Effect of FA/O complexing agents and H₂O₂ on chemical mechanical polishing of ruthenium in weakly alkaline slurry

This paper investigated the effect of FA/O and hydrogen peroxide (H₂O₂) on ruthenium (Ru) removal rate (RR) and static etching rate (SER). It was revealed that Ru RR and SER first linearly increased then slowly decreaseed with the increasing H₂O₂ probably due to the formation of uniform Ru oxides on the surface during polishing. Their corrosion behaviors and states of surface oxidation were analyzed. In addition, FA/O could chelate Ru oxides (such as (RuO₄)^2– and RuO₄⁻ changed into soluble amine salts [R(NH₃)₄] (RuO₄)₂) and enhance Ru RR. The non-ionic surfactant AD was used to improve the Ru CMP performance. In particular, the addition of AD can lead to significant improvement of the surface roughness. (paper)