Electro-plating methods currently used to deposit Cu in through-wafer interconnect applications result in the formation of a thick Cu layer with large amounts of topographical variation. In this paper, alternative methods for thick Cu removal are investigated using a two-step slurry CMP approach.
Miranda, Peter A.; Imonigie, Jerome A.; Erbe, Aaron L.; and Moll, Amy J.. (2005). "Novel Slurry Solutions for Thick Cu CMP". IEEE Workshop on Microelectronics and Electron Devices, 2005, 92-94. http://dx.doi.org/10.1109/WMED.2005.1431630