electromigration

n. transfer of mass which occurs in a metal as a result of the movement of ions under the influence of an electrical current; procedure used to separate isotopes (Chemistry)

Electromigration is the transport of material caused by the gradual movement of the ions in a conductor due to the momentum transfer between conducting electrons and diffusing metal atoms. The effect is important in applications where high direct current densities are used, such as in microelectronics and related structures. As the structure size in electronics such as integrated circuits (ICs) decreases, the practical significance of this effect increases.
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<electronics> Mass transport due to momentum exchange between conducting electrons and diffusing metal atoms. Electromigration causes progressive damage to the metal conductors in an integrated circuit. It is characteristic of metals at very high current density and temperatures of 100C or more.
The term was coined by Professor Hilbert Huntington in the late 1950s because he didn't like the German use of the word "electrotransport".
Mass transoport occurs via the Einstein relation J=DFC/kT where F is the driving force for the transoport. For electromigraiton F is z*epj and z* is an electromigration parameter relating the momentum exchange and z is the charge of the "diffusing" species.
(1999-02-25)

the migration of atoms in a metal interconnect line due to momentum transfer from conduction electrons. The metal atoms migrate in the direction of current flow and can lead to failure of the metal Line. Electromigration depends on the metal in use with a fairly good correlation to the melting temperature of the metal, higher melting temperatures generally correspond to higher electromigration resistance, temperature, higher is worse, and current density, higher is worse. Electromigration may be due to diffusion in the bulk of the material, the grain boundaries or on the surface. Aluminum electromigration is primarily grain boundary due to the higher grain boundary diffusivity over the bulk diffusivity and the excellent surface Passivation effect of aluminum oxide that forms on the aluminum surface when exposed to oxygen. Copper on the other hand, has lower bulk and grain boundary electromigration and primarily exhibits electromigration on the surface due to poor copper oxide passivation properties.