Electromigration (EM) and stress-induced voiding (SIV) in Cu and Cu alloys thin films were studied separately. The characterization of EM was evaluated in a modified interconnect structure where the effect of current density can be observed in the absence of stress disturbance. SIV, on the other hand, is examined in detail by applying a uniform stress to Cu films without electric current. Results of EM tests clearly showed that void and hillock formations were concentrated mainly in the region with high current density gradient without stress disturbance. SIV test performed under the high stress of 1GPa showed that voids were observed to form at grain boundaries and grain boundary triple junctions. Under the high stress, SIV is shown to be generated in the absence of stress gradient. Also, the effect of alloying to EM and SIV was investigated in detail.