Synergetic Effect of 5-Methyl-1H-Benzotriazole and Sodium Dodecyl Benzene Sulfonate on CMP Performance of Ruthenium Barrier Layer in KIO<sub>4</sub>-Based Slurry
Yi Xu, Baimei Tan, Lianjun Hu, Yuling Liu
Abstract
The chemical mechanical polishing (CMP) of ruthenium barrier layer of copper interconnection for 14 nm and below technology node has been connected with more challenges, among which the corrosion of copper and ruthenium and the selectivity of removal rate between ruthenium and copper has attracted more attention. This paper mainly focus on the influence of 5-methyl-1H-benzotriazole(MBTA) and sodium dodecyl benzene sulfonate (SDBS) on the polishing properties of copper and ruthenium during ruthenium barrier CMP in the KIO 4 -based solutions. The results show that the removal rate and corrosion current density of ruthenium decrease with the increase of MBTA concentration. Subsequently, it is demonstrated that the formation of passivating film on ruthenium surface is due to the physisorption of MBTA, which occupies the reaction sites between ruthenium and KIO 4 and inhibits the corrosion of ruthenium. SDBS was introduced to KIO 4 -based solution to compensate for the deficiency of MBTA in inhibiting copper corrosion. It has been proved that the coordinated use of MBTA and SDBS can reduce the copper removal rate to about 326 Å min −1 and obtain acceptable surface morphology. The synergistic inhibition mechanism of MBTA and SDBS on copper corrosion can be elucidated as: under the action of KIO 4 and mixed inhibitors, a dense and integrated passivating film is generated on the copper surface to inhibit the excessive corrosion of copper. The passivating film is comprised of Cu–MBTA complex, adsorbed SDBS, copper oxides, Cu(IO 4 ) 2 and Cu(IO 3 ) 2 . The results of CMP and ZRA experiments represent that the combination of MBTA and SDBS can adjust the removal rate selectivity of copper, ruthenium and low- κ dielectrics to 1.56:1:1.01 and evidently alleviate the galvanic corrosion of copper.