Polarity effect of electromigration in Ni₂Si contacts on Si

The electromigration of contacts in shallow junction devices is a reliability issue for the future very large scale integration technology. The stability of silicide contacts against a high current density is unknown. We have observed a strong polarity effect of the electromigration-induced failure at both Ni/Ni₂Si/n⁺-Si and Ni/Ni₂Si/p⁺-Si contact pairs. They were found to fail preferentially at the cathode. The unreacted Ni/n⁺-Si and Ni/p⁺-Si contact pairs have also been studied. The latter fails at the cathode while the former fails at the anode. Failure mechanisms are proposed to explain the polarity effects. © 1996 The American Physical Society.