Improvement of Ta diffusion barrier performance in Cu metallization by insertion of a thin Zr layer into Ta film

In order to increase the failure temperature of Ta diffusion barrier for Cu, we investigated the effect of insertion of a thin Zr layer into Ta film with/without ion bombardment on Ta diffusion barrier performance in Cu metallization. The insertion of a thin Zr layer into Ta film improved barrier properties significantly when the Ta/Zr/Ta barrier layers were deposited with concurrent ion bombardment. The significant improvement of Ta diffusion barrier properties by insertion of a thin Zr layer into Ta film with ion bombardment was attributed to the densification of grain boundaries in Ta/Zr/Ta films and the formation of an intermixing layer between Ta and Zr by ion bombardment, followed by the reduction of fast diffusion of Cu through Ta/Zr/Ta films.