Electromigration in submicron interconnect features of integrated circuits

Electromigration (EM) is a complex multiphysics problem including electrical, thermal, and mechanical aspects. Since the first work on EM was published in 1907, extensive studies on EM have been conducted theoretically, experimentally, and by means of computer simulation. Today EM is the most significant threat for interconnect reliability in high performance integrated circuits. ears, physicists, material scientists, and engineers have dealt with the EM problem developing different strategies to reduce EM risk and methods for prediction of EM life time. During the same time a significant amount of work has been carried out on fundamentally understanding of EM physics, of the influence of material and geometrical properties on EM, and of the interconnect operating conditions on EM. In parallel to the theoretical studies, a large amount of work has been performed in experimental studies, mostly motivated by urgent and specific problem settings which engineers encounter during their daily work. On the basis of accelerated electromigration tests, various time-to-failure estimation methods with Blacks equation and statistics have been developed. The big question is, however, the usefulness of this work, since most contributions about electromigration and the accompanying stress effects are based on a very simplified picture of electromigration. tention of this review paper is to present the most important aspects of theoretical and experimental EM investigations together with a brief history of the development of the main concepts and methods. We present an overview of EM models from their origins in classical materials science methods up to the most recent developments for submicron interconnect features, as well as the application of ab initio and first principle methods. The main findings of experimental studies, important for any model development and application, will also be presented.