Scaling causes challenges with interconnect reliability. Both time-dependent-dielectric-breakdown (TDDB) and electromigration lifetimes for interconnects drop rapidly. In this paper, a multi-layer SiN cap process is developed that shows higher breakdown and lower leakage compared to conventional SiCNH caps. Selective cobalt caps in combination with the multi-layer SiN cap are shown to provide a 10x improvement in electromigration lifetimes. Wrap-around cobalt liners in combination with the cap layer schemes are shown to provide a 1000x improvement in electromigration lifetimes.
[4.4. D. Priyadarshini, et al., “Advanced Metal and Dielectric Barrier Cap Films for Cu Low k Interconnects”, IBM, Applied Materials]