Enhanced diffusion barrier for interconnect structures

Abstract

Alternative methods of fabricating an interconnect structure in which an enhanced diffusion barrier including an in-situ formed metal nitride liner formed between an interconnect dielectric material and an overlying metal diffusion barrier liner are provided. In one embodiment, at least one opening is formed into an interconnect dielectric material. A nitrogen enriched dielectric surface layer is formed within exposed surfaces of the interconnect dielectric material utilizing thermal nitridation. A metal diffusion barrier liner is the formed. During and/or after the formation of the metal diffusion barrier liner, a metal nitride liner forms in-situ in a lower region of the metal diffusion barrier liner. A conductive material is then formed on the metal diffusion barrier liner. The conductive material, the metal diffusion barrier liner and the metal nitride liner that are located outside of the at least one opening are removed to provide a planarized structure.