Key reliability issues for copper integration in damascene architecture

Electromigration and the effects of Cu concentration in intra-metal dielect rics have been examined: these two key reliability issues are fundamental i n 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 o n the diffusion mechanisms have been studied. Furthermore, the dependence o f the line-width on the current and temperature induced transport mechanism s have been analyzed. Once more, process variations have been demonstrated to influence strongly the final behavior of Cu interconnects in dual-damasc ene architecture. Intra-metal dielectric reliability has also to be conside red 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 inhibi tor could be questionable. (C) 2001 Elsevier Science B.V. All rights reserv ed.