Study of Inhibition Effects on Copper CMP Slurry Performance

With the development of the products with more advanced technology nodes, new challenges continue to emerge in CMP processes. For example, there is a strong need to use lower down force in polishing process while maintaining a high removal rate to avoid low-k/ultra-low k dielectric film damage. The requirements for dishing, overpolish window, Cu residue clearance capability and surface defectivity, especially corrosion related defects become more stringent as copper lines become narrower and narrower. In this paper, we share our research efforts and results in developing a novel copper CMP slurry to overcome these performance challenges in Cu CMP process. In short, a well designed inhibitor system was applied in this slurry. The impacts of these inhibitors on the slurry performance including blanket removal rate/profile, static etch rate, dishing, Cu residue clearance capability and corrosion were evaluated through polishing experiments, electrochemistry evaluations, and laboratory tests simulating CMP aggressive conditions. With a synergetic effect of these inhibition systems, the slurry shows the excellent CMP performance