Cu capping layer deposition with improved integrated circuit reliability

摘要

The electromigration resistance of nitride capped Cu lines is significantly improved by controlling the nitride deposition conditions to reduce the compressive stress of the deposited nitride layer, thereby reducing diffusion along the Cu-nitride interface. Embodiments include depositing a silicon nitride capping layer on inlaid Cu using dual frequency powers, holding the high frequency power constant and controlling the compressive stress of the deposited silicon nitride capping layer by varying the low frequency power to the susceptor, thereby enabling reduction of the compressive stress below about 2x10⁷ Pascals. Embodiments also include sequentially and contiguously treating the exposed planarized surface of in-laid Cu with a soft plasma containing NH₃ diluted with N₂, and then depositing the silicon nitride capping layer by plasma enhanced chemical vapor deposition, while varying the low frequency power between about 100 to about 300 watts. Embodiments also include Cu dual damascene structures formed in dielectric material having a dielectric constant (k) less than about 3.9.