The kinetics of electromigration

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Abstract
A well-known model for the rate of heterogeneous nucleation and growth of a second-phase precipitate in a solid matrix has successfully been applied to electromigration rate studies in metallic thin-film interconnects. The application of these rate equations is based on the analogy between the nucleation and growth of a second-phase precipitate in a solid solution matrix and the nucleation and growth of a void in a thin-film conductor. In the first case, the driving force, at constant composition, is temperature, whereas the driving force for electromigration is both temperature and the applied electric field. Once developed, the model is applied to the resistance versus time data of a variety of thin-film systems, i.e., Al, Al-0.3% Cu, Ti, Ag, Ti/Au, and Au. The results show that this model can accurately be used to describe the failure mechanism in electromigration. Furthermore, if the growth rate of voids is known for a particular thin film, then it is possible to predict failure times.