Method for forming nitride capped Cu lines with reduced hillock formation

摘要

The electromigration resistance of nitride capped Cu lines is significantly improved by treating the exposed planarized surface of inlaid Cu with a plasma containing NH3, depositing a silicon nitride capping layer at reduced temperatures, and then laser thermal annealing in N2 to densify the silicon nitride capping layer. The resulting silicon nitride capping layer also exhibits improved barrier resistance to Cu migration and improved etch stop properties. Embodiments include Cu dual damascene structures formed in dielectric material dielectric constant (k) less than about 3.9.