Ir/TaN as a bilayer diffusion barrier for advanced Cu interconnects

The properties of an Ir (5 nm)/TaN (5 nm) stacked layer as a copper diffusion barrier on Si have been investigated. Ir/TaN bilayer barriers were prepared at room temperature by magnetron sputtering followed by in situ Cu deposition for diffusion tests. Thermal annealing of the barrier stacks was carried out in vacuum at high temperatures for 1 h. X-ray diffraction patterns, cross sectional transmission electron microscopy images, and energy-dispersive spectrometer line scans on the samples annealed at 600 deg. C revealed no Cu diffusion through the barrier. The results indicate that the Ir/TaN bilayer is an effective diffusion barrier for copper metallization