Hybrid Metallization with Cu in sub 30nm Interconnects

Patterns down to 21nm metal pitch (MP) have been used in the hybrid metallization scheme of Ru via prefill followed by a Cu trench metallization. The via resistance for Ru in hybrid with TaNRu/Cu trench fill is benchmarked to Co and Ru dual-damascene (DD) metallization schemes. At 30nm MP, a 40% via resistance reduction is observed upon introducing the Ru prefill prior to the Cu metallization. The Ru prefill significantly improved the via yield for the Cu metallization in 21nm MP. At this dimension, a 35% lower resistance is obtained with the Ru-Cu hybrid system when benchmarked to Co and Ru full fill with a 1nm TiN barrier. The electromigration of the Ru-Cu hybrid system does not a show a performance degradation, making it a viable scaling scenario for DD metallizations in N5 technologies and beyond.