Influence of dielectric layers on electromigration results in Cu interconnects

Electromigration studies showed that an activation energy Ea/spl sim/0.9 eV was obtained in Cu interconnects with SiOC as lateral dielectric for linewidths down to 0.28 /spl mu/m. Failure analysis showed similar EM diffusion path in Cu/SiOC interconnects in comparison to Cu/SiO/sub 2/ interconnects. Moreover electromigration lifetime is improved when a SiC cap layer is used: lifetime is increased in 0.4 /spl mu/m by a factor of 4 in comparison to SiN cap layer.