4-nm thick multilayer structure of multi-component (AlCrRuTaTiZr)Nx as robust diffusion barrier for Cu interconnects

This work develops a multilayer structure of alternating (AlCrRuTaTiZr)N-0.5 senary nitride and AlCrRuTaTiZr senary alloy with a total thickness of only 4 nm as a diffusion barrier layer for application to Cu interconnects. Under annealing at a high temperature of 800 degrees C, the interdiffusion of Cu and Si through the multilayer structure was effectively retarded without the formation of any Cu silicides. Interdiffusion occurred only at 900 degrees C, and compounds that included Cu3Si were thus formed. This finding suggests that the high endurance temperature of the diffusion barrier is probably attributable to the stable amorphous solid-solution structure, the high packing factor, the severe lattice distortions that are caused by the incorporation of multiple components and the elongated diffusion path through the multilayer stacking structure. (C) 2011 Elsevier B. V. All rights reserved.