in sub-micron damascene Cu interconnects, electromigration is mainly due to diffusion at the interfaces of Cu with liner or dielectric cap layer. Many reports have shown Cu/dielectric cap as the dominant diffusion interface. Cu Surface treatment after chemical mechanical polishing (CMP) can be a viable solution to improve electromigration performance of Cu damascene interconnects. In this study, NH3 and H-2 plasma surface treatments were employed after CMP. These surface treatments can alter the Cu/dielectric interface and consequently influence the dominant Cu/dielectric cap interfacial electromigration. Cu damascene electromigration test structures, with sub-micron line-width, were employed in this investigation. Electromigration performance was assessed by package level electromigration tests and H-2 plasma surface treatment was found to significantly reduce electromigration. (C) 2004 Elsevier B.V. All rights reserved.