Effects of electromigration-induced void dynamics on the evolution of electrical resistance in metallic interconnect lines

Abstract

The effects of void dynamics under electromigration conditions on the electrical resistance evolution in metallic thin-film interconnects are examined based on self-consistent dynamical simulations. Changes in the interconnect line resistance are found to depend strongly on electromigration-induced void morphological changes and are explained on the basis of void extension across the linewidth and void surface area evolution at constant void volume. The void morphological evolution may lead to stable steady or time-periodic line resistance response or to abrupt resistance increase associated with failure. Our computational results imply that electrical resistance increases should not be attributed only to void formation or void growth and that electrical resistance oscillations are not due to alternating defect generation and annihilation. The results are in excellent agreement with analytical scaling theories and qualitatively consistent with a large set of experimental electrical resistance measurements.