The effectiveness of a thin refractory metal layer inserted into a Ta filmby ion-assisted deposition as a diffusion barrier between copper and silicon

In order to increase the failure temperature of a Ta diffusion barrier for Cu, we investigated the effect of adding of a thin refractory metal layer i nto a Ta film with/without ion bombardment on the Ta diffusion barrier perf ormance in Cu metallization. The insertion of a thin Zr, W, Nb, or V layer into the Ta film improved the barrier properties significantly when the bar rier layers were deposited with concurrent ion bombardment. The improvement of Ta diffusion barrier property was attributed to a densification of the grain boundaries in the films and to the formation of two thermally stable sharp interfaces between the Ta and the V by the ion bombardment, thereby r etarding the Cu diffusion through Ta/V/Ta films.