Patent ID: 7585768

Claim:
A method of filling an opening comprising: providing a substrate prepared with a dielectric layer with an opening with upper and lower portions, the opening having an aspect ratio; forming a metal barrier layer, the metal barrier layer lining the sides and bottom of the opening in the dielectric layer; forming a copper seed layer on the metal barrier layer; forming a non-conformal first copper layer in only the lower portion of the opening to partially fill the opening, wherein the first copper layer forms on the seed layer and includes a planar top surface, wherein the first copper layer reduces the aspect ratio of the opening; using ECP to form a second copper layer to fill the reduced aspect ratio opening, wherein the first and second fill processes are different types of fill processes, the second copper layer contacts the top surface of the first copper layer; annealing the substrate; and polishing the substrate to form a planar surface with the top of the opening.