Method of forming SiC capped copper interconnects with reduced hillock formation and improved electromigration resistance

摘要

The electromigration resistance of capped Cu or Cu alloy interconnects is significantly improved and hillock formation is significantly reduced by sequentially and contiguously treating the exposed planarized surface of in-laid Cu with a plasma containing NH₃ and N₂, ramping up the introduction of trimethylsilane and then initiating deposition of a silicon carbide capping layer. Embodiments include treating the exposed surface of in-laid Cu with a soft NH₃ plasma diluted with N₂, shutting off the power, discontinuing the N₂ flow and introducing He, then ramping up the introduction of trimethylsilane in three stages, and then initiating plasma enhanced chemical vapor deposition of a silicon carbide capping layer, while maintaining substantially the same temperature of 335° C. throughout plasma treatment and silicon carbide capping layer deposition. Embodiments also include forming Cu dual damascene structures formed in dielectric material having a dielectric constant (k) less than 3.9.