Self-forming VOx layer as Cu diffusion barrier for low-k dielectrics

•We report a Cu–V alloy for the self-forming barrier on various low-k dielectrics.•V-based interlayers were dominated by the oxygen concentration in the dielectric layers.•Investigation help realize effects of dielectric on self-forming barrier formation.

A Cu–V alloy is reported as a material for use in a self-forming barrier process. The diffusion barrier property of a V-based self-formed layer was investigated on various low-k dielectrics. Cu–V alloy films were directly deposited on various low-k dielectrics by co-sputtering, followed by annealing at various temperatures. X-ray diffraction revealed Cu (111), (200) and (220) peaks of the Cu–V alloys. Transmission electron microscopy showed that a uniform V-based interlayer self-formed at the interface after annealing. In order to evaluate the barrier property of the V-based interlayer, the thermal stability was measured with low-k dielectrics. The V-based interlayer formed on the low-k 3 dielectric that contained more oxygen had better thermal stability than that formed on the low-k 1 dielectric that contained less oxygen and more carbon. X-ray photoelectron spectroscopy analysis showed the chemical compositions of the self-formed layer. Furthermore, the results show that the formation of the V-based interlayers was strongly dominated by the oxygen concentration in the dielectric layers.