Effect of Diethanolamine as Corrosion Inhibitor for the Chemical Mechanical Polishing of Cobalt in H2O2 Based Slurry

Abstract

In this article, we investigated the polishing effect of inhibitor diethanolamine (DEA) on cobalt under chemical mechanical polishing (CMP) in a slurry based on complexing agent ammonium sulfate ((NH4)2SO4). DEA is beneficial to inhibit the removal rate of cobalt and significantly reduce surface scratches of post-CMP cobalt in the AFM image. Through electrochemical experiments, the changes of corrosion current and corrosion potential with the increase of DEA concentration are obtained. The results show that by calculating the inhibition efficiency of DEA and the standard free energy of adsorption, the inhibition types of DEA can be determined as physical adsorption (main) and chemical adsorption. The XPS experiment analysis indicates that the chemisorption of DEA is to form a water-insoluble Co-DEA complex by complexing cobalt ions.Through the atomic force microscope to observe the surface condition of cobalt polished with/without EDA. Adding DEA in the slurry is beneficial to reduce the potential difference between Cu-Co and inhibit the galvanic corrosion between Cu-Co.