Key reliability issues for copper integration in damascene architecture

Electromigration and the effects of Cu concentration in intra-metal dielectrics have been examined: these two key reliability issues are fundamental in the development of Cu based interconnects. Several experiments have been performed to highlight the sensitivity of the electromigration performances with respect to the various process variants: the impact of annealing, of dielectric capping SiN deposition process and the role of the environment on the diffusion mechanisms have been studied. Furthermore, the dependence of the line-width on the current and temperature induced transport mechanisms have been analyzed. Once more, process variations have been demonstrated to influence strongly the final behavior of Cu interconnects in dual-damascene architecture. Intra-metal dielectric reliability has also to be considered as a potential reliability issue and bias-temperature stress tests have proven that if the amount of Cu left behind the barrier during the process is not precisely controlled, the role of the barrier as a diffusion inhibitor could be questionable. (C) 2001 Elsevier Science B.V. All rights reserved.