Dissolution of copper thin films in hydroxylamine-based solutions

Chemical mechanical planarization (CMP) of copper, a key processing step in the rapid development of copper interconnect technology, requires the use of a chemical system that can oxidize and complex copper. Hydroxylamine, because of its redox properties and copper complexation ability, is being actively tested for use in copper CMP. Fundamental investigations have been carried out to characterize the dissolution of electroplated copper thin films in hydroxylamine-based solutions. Based on potential-pH diagrams and the data on dependence of copper etch rate on pH, a mechanism for copper dissolution based on the auto-oxidation/reduction of hydroxylamine has been proposed. The effectiveness of benzotriazole (BTA) and salicylhydroxamic acid (SHA) as corrosion inhibitors for copper in hydroxylamine-based chemistries is discussed.