Ultrathin Ru–Ta–C Barriers for Cu Metallization

The use of an ultrathin Ru–Ta–C film as a barrier for copper metallization in sub- ultra-large-scale integration (ULSI) has been evaluated. The films, fixed at , were deposited by magnetron sputtering using Ru and TaC targets, and the film composition and structure were adjusted by tuning the respective deposition power. The structure of the Ru–Ta–C films gradually changed from to nanocrystalline or nearly amorphous when optimizing TaC. For a sandwiched scheme of or , the failure temperature was at least . We also electroplated Cu directly onto a Ru–Ta–C film without Cu seeding. Because of their low resistivity and high thermal stability, Ru–Ta–C films are promising as a Cu barrier.