POLARITY EFFECT OF ELECTROMIGRATION IN NI2SI CONTACTS ON SI

The electromigration of contacts in shallow junction devices is a reli ability issue for the future very large scale integration technology. The stability of silicide contacts against a high current density is u nknown. We have observed a strong polarity effect of the electromigrat ion-induced failure at both Ni/Ni2Si/n(+)-Si and Ni/Ni2Si/p(+)-Si cont act pairs. They were found to fail preferentially at the cathode. The unreacted Ni/n(+)-Si and Ni/p(+)-Si contact pairs have also been studi ed. The latter fails at the cathode while the former fails at the anod e. Failure mechanisms are proposed to explain the polarity effects.