Electromigration is a process of mass transport in metal interconnects induced by high density electrical currents. It is a key failure mechanism in integrated circuits where current densities are high due to miniaturization. The mass transport of metal atoms can result in the formation of hillocks, whiskers, and voids, all leading to the electrical failure of the circuit.

The properties affecting electromigration are highly temperature dependent, and the four fields involved—structural, electrical, thermal, and diffusion—are coupled in many ways. For example, electrically-driven metal diffusion and thermal expansion due to Joule heating cause compression in the conductor (backstress) which can retard and ultimately stop electromigration.

The coupled-field element used in this example employs strong (matrix) coupling, which is essential to obtaining convergence of the four fields. By modeling the four fields simultaneously, you can conveniently specify all the needed material properties and coupling effects in a single analysis.