A graded cap is formed upon an interconnect, such as a back end of line wire. The graded cap includes a microstructure that uniformly changes from a metal nearest the interconnect to a metal nitride most distal from the interconnect. The graded cap is formed by nitriding a metal cap that is formed upon the interconnect. During nitriding an exposed one or more perimeter portions of the metal cap become a metal nitride with a larger amount or concentration of Nitrogen while one or more inner portions of the metal cap nearest the interconnect may be maintained as the metal or become the metal nitride with a fewer amount or concentration of Nitrogen. The resulting graded cap includes a gradually or uniformly changing microstructure between the one or more inner portions and the one or more perimeter portions.