Recent Trends in Copper Metallization

The Cu/low-k damascene process was introduced to alleviate the increase in the RC delay of Al/SiO2 interconnects, but now that the technology generation has reached 1× nm or lower, a number of limitations have become apparent. Due to the integration limit of low-k materials, the increase in the RC delay due to scaling can only be suppressed through metallization. As a result, various metallization methods have been proposed, including traditional barrier/liner thickness scaling, and new materials and integration schemes have been developed. This paper introduces these methods and summarizes the recent trends in metallization. It also includes a brief introduction to the Cu damascene process, an explanation of why the low-k approach faces limitations, and a discussion of the measures of reliability (electromigration and time-dependent dielectric breakdown) that are essential for all validation schemes.