US Patent 10431464 Liner planarization-free process flow for fabricating metallic interconnect structures

A method includes forming a dielectric layer on a substrate and patterning the dielectric layer to form an opening in the dielectric layer. A first layer of metallic material (e.g., non-nitride metal) is deposited to form a liner layer on an upper surface of the dielectric layer and on exposed surfaces within the opening. A second layer of metallic material (e.g., copper) is deposited to fill the opening with metallic material. An overburden portion of the second layer of metallic material is removed by planarizing the second layer of metallic material down an overburden portion of the liner layer on the upper surface of the dielectric layer. A surface treatment process (e.g., plasma nitridation) is performed to convert the overburden portion of the liner layer into a layer of metal nitride material. The layer of metal nitride material is selectively etched away using a wet etch process.