Improved diffusion barrier performance of Ru/TaN bilayer by N effusion in TaN underlayer

► Success synthesis of two bilayers of Ru/N-unsaturated and N-supersaturated TaN. ► RuN exists in Ru/N-supersaturated TaN after annealing at 650 °C. ► Ru/N-supersaturated TaN exhibits high thermal stability. ► N effusion from TaN underlayer is responsible for the high thermal stability.