The interactions between low-k material hydrogenated silicon oxycarbide (SiOC:H) and barrier layers, Ta, TaN, physical-vapor deposition (PVD) and chemical-vapor deposition (CVD) Ti and TiN, have been investigated. The results show these barriers except TaN can react with SiOC:H at evaluated temperature. Furthermore, significant interactions of carbon and oxygen due to the degradation of the SiOC:H films upon annealing exist for all barrier/SiOC:H structures. The CVD-TiN structure can retard the hydrogen out-diffusion, while PVD-TiN structure induces the H out-diffusion from the SiOC:H films. By studying flat band voltage shift in C-V tests, it is demonstrated that Cu+ ions drift into SiOC:H under electric field at elevated temperatures. A thin layer of TaN is proven to be good Cu drift barrier layer with SiOC:H dielectrics. (c) 2007 Elsevier B.V. All rights reserved.