CMP development for Ru liner structures beyond 14nm

For better gap fill in beyond 56nm pitch Cu interconnect structures, Ru liner is one of the most promising solutions with better coverage and wettability. In this paper several new challenges in Ru CMP specific to ≤ 48nm pitch structures (also called 10nm technology) are presented. New CMP solutions were developed by optimizing the slurry, consumables, and process sequence to address the observed challenges such as Ru bending and Cu recess. The optimized solutions to address these challenges were further tested on integrated wafers and improvements in resistance and yield were demonstrated through electrical tests.