Improvement on the diffusion barrier performance of reactively sputtered Ru-N film by incorporation of Ta

Ultrathin Ru-N and Ru-Ta-N films (similar to 15 nm in thickness) deposited by reactive sputtering are applied as a diffusion barrier in the Cu/barrier/SiO(2)/Si systems. After film deposition, the samples are tested before and after annealing at 200-900 degrees C in vacuum for 30 min. The sheet resistance examined by four-point probe appraises that the Ru-Ta-N barrier would not fail until annealing at 900 degrees C, as compared to Ru-N, which fails after annealing at 600 degrees C. 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 600 degrees C. Also, the cross-sectional microstructures of the Cu/barrier/SiO(2)/Si 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/SiO(2)/Si multilayered systems. (c) 2008 The Electrochemical Society.