The evaluation of the diffusion barrier performance of reactively sputtered TaNx layers for copper metallization

Ta-based Cu diffusion barrier properties were widely studied. This work demonstrates that grain boundary diffusivity of Cu diffusion in various TaN_x (x=0~0.62) thin films can be extracted from the copper concentration profile, based on the Whipple analysis of grain boundary diffusion, after annealing the samples at fixed temperatures between 200 and 500°C. We used the grain boundary diffusivity to predict the penetration depth (2√Dt) of Cu in Ta and TaN_x films at fixed temperatures 250 and 400°C. Cu/TaN_x(45 A)/N⁺P junction diode leakage, SIMS and XSEM analysis results indicated that the Whipple model correlates well with experimental results