Electromigration in thin film conductors

Abstract

The state of the art in understanding of electromigration induced failure is outlined in the following review. An overview of the basic principles responsible for electromigration in conductors is followed by an explanation of what the consequences of electron flow directed mass transport are in circuit wiring with an emphasis on the recent appreciation of the role of mechanical stress and where it comes from. The effects of thermal stress, microstructure and precipitation are discussed within this context. Finally, suggestions for further work are made.

Nonpolar resistance switching of metal/binary-transition-metal oxides/metal sandwiches: Homogeneous/inhomogeneous transition of current distribution

“…This value is quite noteworthy, because a macroscopic material transport known as electromigration becomes significant 47,48 in such a high current density environment. In general, electromigration forms nanocracks preferably where the materials transport is inhomogeneous and where the activation energy for diffusion is reduced compared to that of the bulk.…”

Healing Effect of Controlled Anti‐Electromigration on Conventional and High‐Tc Superconducting Nanowires

“…The slope of this graph provides an activation energy U ∼ 0.3 eV which is significantly smaller than the 1.4 eV for the lattice self-diffusion of Al 26,27 but not far from the 0.48 eV reported by Black 4 in polycrystalline samples. This is not surprising considering that both, grain boundary and surface diffusion, are the predominant transport mechanisms with a reduction factor depending on the size of the grains 28 . When constructing the plot shown in the inset of Figure 2g, care must be applied to calculate the temperature T at the constriction, which can largely exceed the bath temperature T B .…”

Effect of strains on anisotropic material transport in copper interconnect structures under electromigration stress

“…First, the electro-thermal problem determines the electric potential and the temperature distribution in the interconnect geometry, which are transfered to the electromigration model. Due to the fabrication process it is expected that anisotropic [14,17] have developed in the interconnects. We have set similar strains into in (5) to reproduce the expected anisotropy.…”

“…The choice of passivating film material together with the corresponding technology process produce tensile or compressive stresses in the interface between the passivating film and the interconnect metal. These stresses can be very high [14] leading to a significant anisotropic diffusion of the metal atoms [15].…”