Currently, there is a steady trend of increasing semiconductor capacity by reducing the characteristic size of integrated circuit elements and developing more densely packed multilevel microelectronic structures. Micro- and submicroelectronics are thus replaced with nanoelectronics. This raises the importance of issues concerning the reliability of nano- and microelectronic components and, consequently, the modeling of their failure and lifetime evaluation. One of the main failures in integrated circuit performance occurs due to electromigration of vacancies (ions) in conductors, which causes their damage.In the present paper we develop a model of electromigration and generation of electromigration-induced mechanical stresses in integrated circuit conductors. We model the electromigration-induced nucleation of a microvoid at a triple point of polycrystalline conductor structure and generation of defects related to the multilevel arrangement of conductors (microvoiding at the contact boundary between the metal line and plug, and erosion of the free end of the line). The characteristic sizes of microdefects and their nucleation times for various temperatures, current densities and crystalline structure parameters of the conductors are numerically calculated.We also put forward an approach to modeling the electromigration and mechanical stresses in conductors containing impurities, such as copper. For the first time a model is proposed for calculating the effective charge of vacancies (ions), which is the major electromigration parameter, in grain boundaries of polycrystalline conductor structure. The dependence of effective charges of aluminum and copper ions in aluminum grain boundary on temperature and boundary texture is simulated numerically.