SIMULATION OF ELECTROMIGRATION FAILURE BY VARIABLE RESISTANCE MODEL

The electromigration failure in a thin metallic conductor has been sim ulated by the temporal resistance change. This change is related to th e crack propagation on both sides of the conductor. The geometrical ch ange affects the two-dimensional electric field distribution, which in turn influences the two-dimensional current density distribution in t he conductor. The two-dimensional electric field and current density m aps can be realized by solving the Laplace equation. By integrating th e power density over the entire conductor, the resistance change due t o the crack development can be obtained. On the other hand, the develo pment of the crack is attributed to the accumulation of vacancies over the cross section of the conductor. We assume that the crack length i s proportional to the excess vacancies over the cross section. From th e one-dimensional diffusion-drift equation, we obtained the temporal g rowth of crack length. The temporal resistance change can thus be simu lated. The effects of vacancy diffusion, and field-induced drift on th e crack-growth kinetics have been demonstrated.