Electro-migration 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.
Electro-Migration is a secondary effect of power being distributed on a chip, where a power trace cross-sectional area at high current levels; diffusing metal atoms can act as a fuse at high current values. The type of metal interconnect layers, such as copper, can reduce the Electro-Migration effect. If a device junction exceeds the Thermal Design Power, then this is one source of reduced reliability. Electro-Migration always exists to some degree, designers need to ensure that it is a negligible factor.
As semiconductor process points get smaller and smaller; then the effect of Electro-Migration increases. As 3nm and 2nm process-points are developed, then this may reduce overall chip reliability?
Wikipedia Web Reference: https://en.wikipedia.org/wiki/Electromigration