In sub-micron damascene Cu interconnects, electromigration was 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 could be a viable solution to improve electromigration performance of Cu damascene interconnects. Here, NH3 and H2 plasma surface treatments were applied after chemical mechanical polishing. These surface treatments could 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 here. Electromigration performance was assessed by package level electromigration tests and H2 plasma surface treatment was found to significantly reduce electromigration.

Effect of Surface Treatment on Electromigration in Sub-Micron Cu Damascene Interconnects. A.V.Vairagar, S.G.Mhaisalkar, A.Krishnamoorthy: Thin Solid Films, 2004, 462-463, 325-9