Patent ID: 6878621

Claim:
A method for forming a metal structure, comprising: providing a substrate having at least a first dielectric layer formed thereover and a first metal structure within the first dielectric layer; providing a second dielectric layer over the first dielectric layer and the first metal structure; patterning the second dielectric layer to form at least one opening there through and exposing at least one portion of the first metal structure; the at least one opening having side walls and a bottom; then forming at least one second metal structure within each opening; each second metal structure having side walls, a bottom and a top; removing the second dielectric layer and at least a portion of the first dielectric layer to expose the top and at least a portion of the side walls of the second metal structure and at least a portion of the first metal structure; forming a dielectric barrier layer over the exposed top and side walls of the first and second metal structures; and forming a third, conformal dielectric layer over the dielectric barrier layer to complete the at least one barrierless metal structure; the dielectric barrier layer preventing diffusion from the barrierless metal structure into the third, conformal dielectric layer.