Abstract: Electromigration is the transport of atoms in metal conductors at high electronic current-densities which creates voids in the conductors and increases the conductors’ electrical resistance.It was delineated in 1961 by Huntington;then modeled by the empirical electrical resistance formula derived by Black in 1969 to fit the dependences of the experimental electrical resistance and failure data on the electrical current density and temperature.Tan in 2007 reviewed 40-years’ applications of the empirical Black formula to conductor lines interconnecting transistors and other devices in silicon integrated circuits.Since the first Landauer theory in 1957,theorists have attempted for 50 years to justify the drift force or electron momentum transfer assumed by Black as some electron-wind force to impart on the metal atoms and ions to move them.Landauer concluded in 1989 that the electron wind force is untenable even considering the most fundamental and complete many-body quantum transport theory.A driftless or electron-windless atomic void model for metal conductor lines is reviewed in this article.It was developed in the mid-1980 and described in 1996 by Sah in a homework solution.This model accounts for all the current and temperature dependences of experimental resistance data fitted to the empirical Black formula.Exact analytical solutions were obtained for the metal conductor line resistance or current,R(t)/R(0)=J(t)/J(0)=［1-2(t/τα)1/α］-1/2, in the bond-breaking limit with α=1 to 2 and diffusion limit with α=2 to 4,from low to high current densities, where τα is the characteristic time constant of the mechanism, containing bond breaking and diffusion rates and activation energies of the metal.

Key words: electromigration, driftless void model, empirical Black formula, diffusion-generation-recombination-trapping