Inhibition Mechanism of Benzotriazole in Copper Chemical Mechanical Planarization

During the process of chemical mechanical planarization (CMP) of copper, benzotriazole (BTA) is the most commonly used inhibitor in the slurry. Though the corrosion inhibition mechanism has been studied widely, the mechanism of BTA layer on copper surface in CMP slurries should be further investigated. In this paper, the adsorption mechanisms of BTA were studied by static corrosion tests. Besides, the surface composition was measured by XPS. Combining with CMP experiments, the material removal mechanism of copper CMP depending on pH values was investigated. It was found that the formation of passive film, consisting of Cu-BTA complex, adsorption of BTA and copper oxides, played a dominant role under acidic conditions. While the surface film composed of adsorption layer of BTA and copper oxides under alkaline conditions. The inhibition mechanism of BTA varied with pH values, resulted in corresponding changes of material removal rate and coefficients of friction.