Abstract
AbstractChemical mechanical polishing (CMP) has long been recognized as a viable technique for global planarization to delineate metal patterns for sub-micron integrated circuit (IC) processing. Copper (Cu) has been used as multilevel interconnects and have emerged as the most important material for such applications. But, unlike Al, Ti, Ta and W, the oxides layer of Cu can be porous or not stable on the copper surface and can easily dissolute from the surface.In this study, in-situ electrochemical measurements were used to investigate the influences of nitric acid concentrations and additives on the copper corrosion mechanism.1.There formed electrochemical double layer (EDL) and unstable oxide passivation while copper immunity in 3% nitric acid slurry. The EDL becomes dense and oxide polished in abrasion.2.In adding of citric acid, it inhibits the reduction of NO3- and reduces total reaction rate, but main reaction mechanisms are still the same as that in 3% nitric acid slurry. In abrasion, the inhibit effects becomes slightly because citric acid becomes hard to diffuse into the interface between polishing pad and metal surface and inhibits cathode reactions and unstable oxide is polished.3.In adding of BTA, Cu+ will complex with BTA and formed a stable Cu-BTA film that inhibits the dissolution reaction rates. In abrasion, the effect of BTA also becomes slightly because Cu-BTA will be polished and formed another kind of dynamic equilibrium and thinner Cu-BTA film.In changing of mechanism conditions in CMP:1.Because all reactions achieve to dynamic equilibrium in abrasion, and the influence of changing pressure conditions seems slightly.2.In different rotation rates the impedance decreases as the sequence of rotation rate increases.3.In different additive concentrations, it shows inhibit effective increases with the additives concentrations increase without abrasion, but it seems slightly in abrasion