Damascene Copper Electroplating For Chip Interconnections

We have been the first to use electroplated Cu in chip interconnections which we have been fabricating with the Damascene process since the beginning of the 1990's. We review here the challenges of filling trenches and vias with Cu metal without creating a void or seam, and the discovery the electrodeposition can be engineered to give filling performance significantly better than that achievable with perfect conformal step coverage. This attribute of super-conformal deposition, which we call "superfilling," and its relation to plating additives are discussed, and we present a numerical model that represents the shape-change behavior of this system.