Electromigration-induced failure mechanisms were investigated by means of extremely sensitive resistance change measurements and simultaneous observations using scanning electron microscopy. Abrupt changes in resistance ( ACRs), classified into three types: downward steps, upward steps, and oscillations, were found to occur frequently during the dc current stressing test. It was conspicuously observed that there was a rapid void annihilation associated with an abrupt increase in resistance, and

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... a rapid void formation with a decrease in resistance. ACRs are considered to be caused by a rapid change in the number of excess vacancies concomitant with void annihilations or formations. The thermodynamical analysis on the stability of a void strongly suggests that the change of a local stress from tensile to compressive causes a rapid annihilation of voids, and the opposite one causes a rapid formation. Temperature dependence of the intensity of ACRs exhibited an activation energy of 0.43 eV, which implied that grain boundary electromigration was the driving force of ACRs. 207