Electromigration characterization for multilevel metallizations using textured AlCu

Electromigration lifetime dependence on crystallographic texture for AlCu interconnects is determined. It is found that enhancement of AlCu texture at <111> orientation improves EM endurance. But this beneficial effect is limited after a certain level of texture enhancement is reached. The effect of lifetime improvement is proved to result from a decrease in atomic diffusivity. Saturation of the lifetime improvement effect for highly textured AlCu indicates a change in the main diffusion mechanism for electromigration, possibly from the regular grain boundary diffusion to diffusion through edge dislocations.