In this work, we have investigated the diffusion barrier performance of Mo and MoxN films deposited by direct current sputtering between the Cu and Si substrates. theta-2theta X-ray diffraction patterns showed the temperature of the Cu3Si phase formed in three different structures. The results of scanning electron microscopy indicated the morphological evolution of the sample surfaces after annealing at different temperatures. Four-probe measurements showed that the MoxN barrier was better at maintaining the good electrical performance of the Cu metallization system than the Mo barrier. (C) 2003 Elsevier B.V. All rights reserved.