Three anionic surfactants for corrosion inhibition in cobalt CMP: Research on validity and mechanism

Inhibitors are introduced into the slurry to avoid excessive metal corrosion during the chemical mechanical polishing (CMP) process. The anti-corrosion effect of surfactants in CMP was not investigated systematically in past studies. In this paper, three eco-friendly anionic surfactants, potassium laurate, potassium oleate, and dodecyl benzenesulfonic acid, were studied in depth as cobalt CMP inhibitors. Electrochemical experiments demonstrated that the three inhibitors act as anodic inhibitors. Static etching tests and surface morphology analysis proved that they can effectively inhibit the corrosion rate of cobalt and improve surface morphology. XPS results demonstrated that the inhibitor reduces corrosion by inhibiting cobalt oxidation. DFT calculations demonstrated that inhibitors adsorb on the cobalt surface through the O atoms in hydrophilic groups, while the CC double bond and benzene ring can significantly enhance the adsorption. Molecular dynamics simulations showed that the inhibitors are adsorbed on the cobalt surface in parallel. Additionally, all three surfactants improved the solution's wettability on cobalt. This report provides critical insights into the corrosion inhibition specific to cobalt CMP and offers an approach to realize the multi-functionality of a single agent in slurries.