Corrosion Inhibitors in Sodium Periodate Slurry for Chemical Mechanical Planarization of Ruthenium Film

The effect of organic inhibitors on pitting in Ruthenium (Ru) was investigated after chemical mechanical planarization (CMP) in near-neutral pH using colloidal silica-abrasive based slurry with an oxidizer, sodium periodate. Organic inhibitors with amine or amide functional groups only demonstrated a strong effect on suppressing pitting, which was proven by the static etch rate, corrosion current density, and oxidation states (RuO3/RuO2 ratio). Ethylenediamine tetraacetic acid had an extremely low surface roughness (∼2 Å) and a reasonable polishing rate (∼1050 Å/min) after CMP, which probably resulted from the relatively low corrosion efficiency (57.7%), low RiO3 content (5.9%), and chelating effect.