Improvement on the Diffusion Barrier Performance of Reactively Sputtered Ru–N Film by Incorporation of Ta

Ultrathin Ru–N and Ru–Ta–N films ( in thickness) deposited by reactive sputtering are applied as a diffusion barrier in the Cu/barrier/ systems. After film deposition, the samples are tested before and after annealing at in vacuum for . The sheet resistance examined by four-point probe appraises that the Ru–Ta–N barrier would not fail until annealing at , as compared to Ru–N, which fails after annealing at . The depth distribution of elements examined by Auger electron spectroscopy confirms different degrees of Cu diffusion into underlayers for the two systems after annealing at . Also, the cross-sectional microstructures of the Cu/barrier/ samples analyzed by transmission electron microscopy, the crystallinity of barrier films examined by grazing incident angle X-ray diffraction, and the chemical state of barrier characterized by X-ray photoelectron spectroscope might explain the difference in barrier performance for the ultrathin Ru–N and Ru–Ta–N films in the Cu/barrier/ multilayered systems.