Abstract: The history of electromigration (EM) modeling of IC interconnects is briefly reviewed. The widely used one-dimension (1-D) EM-induced back flow model is introduced. Based on the conception of atomic flux divergence (AFD), the EM modeling can also be mainly grouped into two approaches. One is the conventional diffusion path approach, which has explained many important phenomena in traditional Al on-chip metallization. However, the microelectronic industry has turned to Cu/low-k interconnects in need of better performances of the shrinking chip, and three-dimensional (3-D) integrated circuit technology is also introduced. In this trend, the driving force approach is developed, which can help to understand many phenomena in narrow interconnection. The finite element modeling (FEM) is used more and more in the driving force formalism.