Wafer cleaning solution for cobalt electroless application

Abstract

A method and cleaning solution that removes contaminants from a dielectric material and polished surfaces of copper interconnect structures prior to an electroless deposition of a capping layer without substantially adversely affecting the interconnect formed therefrom are disclosed. The cleaning solution includes combinations of a core mixture and sulfuric acid or sulfonic compounds such as sulfonic acids that include methanesulfonic acid. In one embodiment, the core mixture includes a citric acid solution and a pH adjuster such as tetra-methyl ammonium hydroxide or ammonia. One embodiment of the method includes providing a planarized substrate, applying the cleaning solution to the substrate to simultaneously clean at least one metal feature and a dielectric material of the substrate, and depositing the metal capping layer selectively on the at least one metal feature using electroless deposition.