Frequency-dependent failure mechanisms of nanocrystalline gold interconnect lines under general alternating current

Abstract

Thermal fatigue failure of metallization interconnect lines subjected to alternating currents (AC) is becoming a severe threat to the long-term reliability of micro/nanodevices with increasing electrical current density/power. Here, thermal fatigue failure behaviors and damage mechanisms of nanocrystalline Au interconnect lines on the silicon glass substrate have been investigated by applying general alternating currents (the pure alternating current coupled with a direct current (DC) component) with different frequencies ranging from 0.05 Hz to 5 kHz. We observed both thermal fatigue damages caused by Joule heating-induced cyclic strain/stress and electromigration (EM) damages caused by the DC component. Besides, the damage formation showed a strong electrically-thermally-mechanically coupled effect and frequency dependence. At lower frequencies, thermal fatigue damages were dominant and the main damage forms were grain coarsening with grain boundary (GB) cracking/voiding and grain thinning. At higher frequencies, EM damages took over and the main damage forms were GB cracking/voiding of smaller grains and hillocks. Furthermore, the healing effect of the reversing current was considered to elucidate damage mechanisms of the nanocrystalline Au lines generated by the general AC. Lastly, a modified model was proposed to predict the lifetime of the nanocrystalline metal interconnect lines, i.e., that was a competing drift velocity-based approach based on the threshold time required for reverse diffusion/healing to occur.

Electromigration-induced resistance switching in indented Al microstrips

“…Even for the case of no resistance variation at all, i.e. when the system is driven at current densities much lower than the EM current, there is an inevitable thermal fatigue loading generated by the alternating current which may lead to a premature breakdown of the device [38][39][40][41].…”

A Review of Self-healing Metals: Fundamentals, Design Principles and Performance

“…In addition to structural applications of the electrohealing, the self-healing approach is also being studied for solders, submicron aluminum and nanocrystalline gold interconnectors to solve the electromigration problems, the significance of which increases notably as the size of integrated circuit decreases [57][58][59][60][61]. Electrical testing showed that cracks formed due to electromigration can disappear upon the application of a high-density current of the right duration.…”

Morphological evolution and migration behavior of silver thin films on flexible substrates during thermal cycle testing

“…The combination of SM and TF may cause cracks, voids, and hillocks to form in the thin films, leading to a deterioration of the electrical conductivity. 7,8 TF failure of metallization interconnect lines subjected to alternating currents has been reported, 9–12 and the damage and failure were caused the deformation-induced motion of dislocations to the grain boundaries. However, TF in the printed Ag film has not been investigated.…”