Microfailure of thin-film interconnects by electromigration is one of the primary causes of degradation of the reliability of microelectronic circuits. This study analyzed the electromigration failure time considering the thermal stress effect in the interconnect. The thermal stress is generated by the difference of thermal expansion coefficients between the metal interconnect and the oxidized silicon substrate. This thermal stress, which is developed during fabrication, produces defects, such as microvoids which accelerate the electromigration. The effect of thermal stress on the electromigration failure time was analyzed via kinetic considerations. For those, after applying different ther mal cycles to develop various thermal stresses in the test specimens, the MTF (mean time to failure) was evaluated by measuring the change of electrical resistance during the electromigration test. Then, the apparent activation energy for electromigration was calculated. The experimental results show that the apparent activation energy and MTF tend to decrease with increasing thermal stress. Microvoids due to thermal stress are an important factor in accelerating the electromigration failure. The presence of stress-induced microvoids was ascertained by the fact that the initial resistance increased with increasing thermal stress.