Patent attributes
A method for treating a copper surface of a semiconductor device provides exposing the copper surface to a citric acid solution after the surface is formed using CMP (chemical mechanical polishing) or other methods. The citric acid treatment may take place during a cleaning operation that takes place in a wafer scrubber, or subsequent to such an operation. The citric acid treatment removes copper oxides that form on copper surfaces exposed to the environment and prevents hillock formation during subsequent high temperature operations. The copper surface is then annealed and the annealing followed by an NH3 plasma treatment which again removes any copper oxides that may be present. The NH3 plasma operation roughens exposed surfaces improving the adhesion of subsequently-formed films such as a dielectric film preferably formed in-situ with the NH3 plasma treatment. The subsequently-formed film is formed over an oxide-free, hillock-free copper surface.
