Patent ID: 8809183

Claim:
A method of forming a metal interconnect structure comprising: forming an underlying dielectric layer on a substrate, wherein the underlying dielectric layer is comprised of a porous material; forming a metal line within said underlying dielectric layer, wherein said metal line has a top surface that is coplanar with a top surface of said underlying dielectric layer; depositing a conductive cap selectively on said metal line, wherein said conductive cap is not deposited directly on said underlying dielectric layer; forming a dielectric material layer over said conductive cap and an entirety of said underlying dielectric layer without exposing said underlying dielectric layer to any preclean, wherein the dielectric material layer is non-porous; planarizing said dielectric material layer, wherein a planarized top surface of said dielectric material layer is coplanar with a top surface of said conductive cap and a bottommost surface of said dielectric material layer is coplanar with said top surface of said metal line, and wherein planarized dielectric material layer portions of said dielectric material layer remain on said entirety of said underlying dielectric layer; and precleaning a topmost surface of said conductive cap to remove metal oxide from said topmost surface of the conductive cap and to provide a topmost non-oxidized metal surface, wherein said precleaning occurs after said planarizing said dielectric material layer.