Chemical and Mechanical Properties of Cu Surface Reaction Layers in Cu-CMP to Improve Planarization

Chemical and mechanical properties of a surface reaction layer are essential to improve planarization in Cu-CMP. We compared the reaction layers on Cu surfaces formed by dipping in APS and H2O2 slurries and show that a thinner, mechanically stronger, and corrosion-resistant layer is preferable. It enables preferential polishing of the convex surfaces and consequently relaxes dishing after Cu-CMP. Controlling Cu oxidation reaction to form Cu2O in the slurry is essential for achieving further improvements of the planarization.