Study on the Adsorption and Inhibition Mechanism of 1,2,4-Triazole on Copper Surface in Copper Interconnection CMP

The chemical mechanical planarization (CMP) has been a key technology in the copper interconnection process of dual damascene. Corrosion inhibitors are often used as an important component in CMP slurry to protect the copper from corrosion at the recess to obtain a high or low selectivity ratio for copper removal rate. 1,2,4-triazole (TAZ) has been recently reported to be a promising inhibitor that can replace benzotriazole(BTA). It has been proved that 0.045M TAZ can achieve the same chemical protection as 0.002M benzotriazole on copper surface. The present study investigates the adsorption passivation reaction between different treated copper samples and a representative corrosion inhibitor TAZ. The three kinds of copper samples treated with as received, citric acid and citric acid + H2O2 were soaked in TAZ solution of 0.05M. The change of adsorption characteristics of copper surface was examined by contact angle measuring instrument, the formation of Cu-1,2,4-triazole was quantified by electrochemical impedance spectroscopy (EIS) and the change of chemical elements on copper surface was analyzed by X-ray photoelectron spectroscopy (XPS). Based on the experimental results, it can be concluded that TAZ can react on the surface of copper to form a weak passivation film of Cu-1,2,4-triazole, and TAZ is preferentially adsorbed on the copper surface treated with citric acid+H2O2.