This study finds that the resistivity of Ta/TaNx films depends on both the Ar re-sputtering amount and the N-2 flow of under-layer TaNx deposition. As the Ar re-sputtering amount of under-layer TAN, films increases, the resistivity of Ta/TaNx bi-layers decreases because Ar re-sputtering can provide a driving force to make the upper Ta metal phase transformation from a high-resistivity beta-phase to a low-resisitivty alpha-phase. On the other hand, increasing the N-2 flow Of under-layer TAN, deposition also makes the Ta resistivity trend down. The behavior is because increasing the N-2 flow can lower the energy barrier of phase transformation from p-phase Ta to a-phase Ta. A proposed model is provided to describe the effect of the Ar re-sputtering amount and the N-2 flow of under-layer TAN, deposition on the phase transformation of upper Ta metals. (C) 2007 Elsevier B.V. All rights reserved.