Interfacial reactions and nucleation of WAl12 phase on electromigration in hydrogen exposed semiconductor interconnects

Abstract

This research aims to investigate the wire reliability in super-thin interconnects after being subjected to a high-heat treatment. The electromigration (EM) fail tendency is analyzed for different annealing conditions with respect to the location of occurrence of the void. When the void occurs within the metal wire, no meaningful difference is observed for different annealing conditions. However, when the void occurs at the upper part of the W plug, which is the initial failure part, different characteristics are observed for different annealing conditions. As the annealing temperature increases from 400 to 450 ℃, the number of samples that fall under the initial failure region increases and melting is observed. When the annealing time at 450 ℃ increases from 30 to 90 min, the samples under the initial failure area decrease. The melting phenomenon observed when annealing at 450 ℃ is believed to be caused by the WAl12 generated at 450 ℃. The melting indicates an increase in the leakage current, which is accompanied by an open-type failure. However, unexpectedly, 90 min of annealing at 450 ℃ does not produce any problem in terms of reliability.