Two bilayers of Ru/TaN with low N concentration and high N concentration (TaNL and TaNH) were used to determine the effect of N effusion on the barrier property. The results show that Ru/TaNH bilayer exhibits a better barrier property, in which RuN existed even after annealing at 650 degrees C. The improved barrier property is attributed to the formation of RuN and N atoms stuffing in grain boundaries of Ru layer by sufficient effusion N atoms from TaNH during annealing. (C) 2012 Elsevier B.V. All rights reserved.