Patent ID: 8669176

Claim:
A method of forming a device, comprising: providing an integrated circuit structure comprising: a first interlayer dielectric (ILD) formed above a substrate; a first plurality of trenches formed in the first ILD; a first barrier layer formed over the first ILD; and a first copper layer formed over the first barrier layer; removing a portion of the first copper layer to form a first plurality of copper structures flush with the first barrier layer; removing a portion of the first plurality of copper structures flush with the first barrier layer to form a first plurality of recessed copper structures; forming a first cap layer over the first plurality of recessed copper structures and the first barrier layer; removing a portion of the first cap layer and a portion of the first barrier layer to form a first plurality of cap structures flush with the first ILD; and forming a second cap layer over the first ILD, the first barrier layer and the first plurality of cap structures, wherein the first cap layer and the second cap layer are made of the same material.