Ru incorporation on marked enhancement of diffusion resistance of multi-component alloy barrier layers

In this study, amorphous AlCrTaTiZr quinary alloy and 20 at.% Ru-incorporated AlCrTaTiZrRu senary alloy films were developed as diffusion barrier layers to inhibit Cu diffusion in interconnect structures. Under annealing at 700 °C, the interdiffusion of Cu and Si through the AlCrTaTiZr quinary alloy layer of 50 nm thick occurred, and compounds including Cu3Si consequently formed. In comparison, at 800 °C, the interdiffusion was still effectively retarded by the Ru-incorporated AlCrTaTiZrRu senary alloy layer of only 5 nm thick without obvious formation of silicides. It suggests the high diffusion resistance of the Ru-incorporated barrier layer possibly attributed to the large lattice distortions caused by the addition of extra-large-sized Ru atoms.