Experimental and Computational Studies on Octyl Hydroxamic Acid as an Environmentally Friendly Inhibitor of Cobalt Chemical Mechanical Polishing

Octyl hydroxamic acid (OHA) was investigated as an inhibitor in H2O2-based alkaline silica dispersions for the polishing of cobalt (Co) films for interconnect applications. A combination of experiments and density functional theory (DFT) was used to investigate the inhibition effect and the mechanism of OHA on the Co surface. On the basis of the experiments, it can be proven that OHA has an inhibition effect on Co, which came from the inhibition of the cathodic reaction. The X-ray photoelectron spectroscopy (XPS) experiments show that the adsorption of OHA weakened the oxidation of the Co surface and protected the Co surface from corrosion. On the basis of the calculations, it can be proven that the OHA(ketone)(ion) is most likely to react with the Co surface, and it can adsorb on the Co surface by Co-O bonds. This study provides important microscopic insights for understanding the corrosion protection of Co interconnect metals and helps to explain the corrosion inhibition mechanism of the organic-metal interface during the CMP process.