Chemical and Mechanical Characterizations of the Passivation Layer of Copper in Organic Acid Based Slurries and its CMP Performance

Abstract

During a Cu CMP process, a passivation layer was grown on Cu surface due to oxidant in slurry. This layer was etched and removed by chemical and mechanical abrasion. H2O2 was used as the oxidant in alumina Cu CMP slurry with citric and oxalic acids. The higher the peroxide concentration, the thicker the oxide on Cu. The static etching rate of Cu decreased and the removal rate increased as the peroxide concentration in slurry was increased. The removal rate increased until the pH value increased to 6 in both citric and oxalic acid added slurries. High removal rate of Cu was observed in the oxalic acid slurry even without adding any abrasive particles.