For the required reduction in the effective dielectric constant of inter-metal dielectrics (IMD) and inter layer dielectrics (ILD) in Cu dual damascene interconnects (DDI), two potential low-k dielectric barrier materials, viz., SiCO and SiCN, were investigated and compared with conventional SiN film in terms of chemical composition and barrier resistance to Cu diffusion. Fourier transform infrared spectra (FTIR) indicate that the CH3 group incorporated into SiCO and SiCN films may be responsible for a reduction in the dielectric constant. SiCO film exhibits a better Cu diffusion depth profile than SiCN film after annealing in the temperature range 200-400 degreesC. However, the Cu penetration SiCO may rapidly increase in the annealing temperature range of 500-600 degreesC. SiCN film exhibits a stable performance against Cu penetration over the temperature range of 200-800 degreesC. (C) 2004 Elsevier B.V. All rights reserved.