Effect of thin V insertion layer into Ta film on the performance of Ta diffusion barrier in Cu metallization

In order to increase the failure temperature of Ta diffusion barrier for Cu , we investigated the effect of a thin V insertion layer (100 Angstrom) int o Ta film with/without ion bombardment on Ta diffusion barrier performance in Cu metallization. When the Ta/V/Ta diffusion barrier was deposited witho ut concurrent ion bombardment, the insertion of the thin V layer into Ta fi lm was not effective to improve the barrier performance of Ta film, because of the thermal instability of the Ta/V/Ta multilayer caused by the reactio n between the Ta/V/Ta films and Si substrate. Meanwhile, when the Ta/V/Ta d iffusion barrier was deposited with ion bombardment, the insertion of the t hin V layer into Ta film improved barrier properties significantly. This wa s attributed not only to the densification of grain boundaries in Ta/V/Ta f ilms, but also to the formation of two thermally stable sharp interfaces be tween Ta and V by ion bombardment, resulting in the reduction of the fast d iffusion of Cu through Ta/V/Ta films. (C) 1999 American Institute of Physic s. [S0021-8979(99)02909-6].