ELECTROMIGRATION AND RELATED FAILURE MECHANISMS IN INTEGRATED-CIRCUITINTERCONNECTS

Electromigration, that is, the forced motion of metal ions under the i nfluence of an electric field, is potentially one of the most pernicio us failure mechanisms in interconnects of large scale integrated micro electronic devices. The momentum exchange between the electrons and th e ions causes the latter at normal operating conditions (under 200-deg rees-C) to migrate predominantly via grain boundaries leading, eventua lly, to voids and extrusions near grain boundary triple points and to a failure of an entire device. This review presents the current unders tanding of electromigration and other related failure mechanisms in th in film metallisations for microelectronic devices. The largest sectio n of this review summarises the influence of various microstructural p arameters on void formation, such as grain size, grain orientation, te xture, stripe dimensions, etc. Other sections emphasise temperature gr adients, thermomigration, grain boundary grooving, activation energies for electromigration, barrier layers, passivations, multilayered inte rconnects, pulsed electromigration, stress voiding, and computer model ling of failure modes.