Ultrathin ZrBxOy films as diffusion barriers in Cu interconnects

• Ultra-thin amorphous ZrBxOy films 5 nm in thickness were fabricated by radio-frequency magnetron sputtering.
• The ultra-thin amorphous ZrBxOy films can exist stably up to at least 500 °C.
• They can be adopted as diffusion barrier in Cu interconnects to block the inter-diffusion between Cu and Si atoms.

Ultra-thin ZrBxOy films 5 nm in thickness were prepared by radio-frequency (rf) magnetron sputtering. The thermal stability and the barrier performance against the inter-diffusion between Cu and Si were studied via thermal annealing at different temperatures. The as-deposited amorphous ZrBxOy thin films could effectively block the inter-diffusion of Cu and Si atoms. However, the thin films became invalid at temperatures higher than 600 °C and significant atomic diffusion occurred, resulting in high-resistivity Cu3Si compound. Hence, ZrBxOy thin films can be exploited as diffusion barriers in Cu interconnects at temperatures lower than 600 °C.