For the improvement of microelectronic thin film interconnection materials, dielectric passivation effects on the electromigration phenomena were studied. Using Al-1%Si, various shaped patterns were fabricated and dielectric passivation layers of several structures were deposited on the $SiO_2$ layer. Lifetime of straight pattern showed 2~5 times longer than the other patterns that had various line width and area. It is believed that the flux divergence due to the structural inhomogeneity and so the current crowding effects shorten the lifetime of thin film interconnections. The lifetime of thin film interconnections seems to depend on both the passivation materials and the passivation thickness. PSG/$SiO_2$ dielectric passivation layers showed longer lifetime than $Si_3N_4$ dielectric passivation layers. This results from the PSG on $SiO_2$ layer reduces stress and from the improvement of resistance to the moisture and to the mobile ion such as sodium. This is also believed that the lifetime of thin film interconnections seems to depend on the passivation thickness in case of the same deposition materials.