Electromigration and related failure mechanisms in integrated circuit interconnects

AbstractAbstractElectromigration, that is, the forced motion of metal ions under the influence of an electric field, is potentially one of the most pernicious failure mechanisms in interconnects of large scale integrated microelectronic devices. The momentum exchange between the electrons and the ions causes the latter at normal operating conditions (under 200°C) to migrate predominantly via grain boundaries leading, eventually, to voids and extrusions near grain boundary triple points and to a failure of an entire device. This review presents the current understanding of electromigration and other related failure mechanisms in thin film metallisations for microelectronic devices. The largest section of this review summarises the influence of various microstructural parameters on void formation, such as grain size, grain orientation, texture, stripe dimensions, etc. Other sections emphasise temperature gradients, thermomigration, grain boundary grooving, activation energies for electromigration, barrier layers, passivations, multilayered interconnects, pulsed electromigration, stress voiding, and computer modelling of failure modes.