Impurity diffusion from the flexible metal substrate into CIGS absorption layer can remarkably reduce cell performance comparing with conventional glass substrate. A diffusion barrier layer lying between the metal substrate and Mo backcontact layer is required to prevent this spread of impurities. In this paper, a set of Si3+xN4-x barrier layers are grown on stainless steel sheets and alloy foils by the magnetron sputtering under different conditions. The morphological, structural and electrical properties of the samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and I-V measurements. Our results indirectly support good blocking effect of Si3+xN4-x barrier to the metal impurities from the stainless steel substrate.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.