XPS Diffusion analysis of Ta(N)/Ru Diffusion Barriers for Cobalt Interconnects

This work examines barrier systems of metallization layers made up of novel materials for next generation computing. The diffusion of cobalt into a Ta/Ru as well as a TaN/Ru layer was analyzed by XPS depth profiles after annealing. The diffusion coefficients were estimated by applying the Mixing-Roughness-Information Depth (MRI) model to the concentration profile of cobalt and the activation energy for diffusion was calculated for both materials. Furthermore the thin films were analyzed regarding their crystal structure change upon annealing. Diffusion coefficients of D(Co in Ta/Ru) ~ 6.162e–13 exp(−139.7/RT) m
²
/s and D(Co in TaN/Ru) ~ 2.9948e–16 exp(−87.63/RT) m
²
/s were estimated.