Effect of Carbon-Doped Cu(Ni) Alloy Film for Barrierless Copper Interconnect

In this study, the barrier properties and diffusion behavior of carbon-doped Cu(Ni) alloy film were investigated. The films were fabricated using magnetron sputtering on a barrierless silicon substrate. X-ray diffraction patterns and electric resistivity results demonstrated that the barrierless Cu(NiC) alloy films remained thermally stable up to 650 °C. Transmission electron microscopy images provided the presence of a self-formed diffusion layer between the Cu(NiC) alloy and Si substrate. The effect of carbon-doped atoms on the diffusion behavior of the Cu(NiC) films was analyzed by X-ray photoemission spectroscopy depth profile. Results revealed that carbon doping can improve the barrier properties of barrierless Cu(Ni) film. Moreover, X-ray photoemission spectroscopy was performed to examine the chemical states of the self-formed layer at the Cu(NiC)/Si interface. The self-formed diffusion layer was found to consist of Cu metal, Ni metal, Si, Cu2O, NiO, and SiO2.