Effects of Thermal  N 2 Annealing on Passivation Capability of Sputtered Ta(‐N) Layers Against Cu Oxidation

The effects of thermal annealing on the passivation capability of sputtered Ta and Ta‐nitride [Ta(‐N)] layers against Cu oxidation in a 200 Å Ta(‐N) covered Ta(‐N)/Cu/ /Si structures was investigated. The annealed Ta layers revealed degradation in passivation capability, presumably due to grain growth of the Ta passivation layer. In contrast, the nitrogen‐doped Ta‐nitride layers showed a contrary trend. For the Ta‐nitride layer with 23.5 atom % of nitrogen, passivation capability was effectively improved by annealing at 300°C. For the Ta‐nitride layer with 30.5 atom % of nitrogen, annealing at higher temperatures (500–700°C) was necessary to improve the passivation capability. The healing of sputtering damage of Ta‐nitride passivation layers by the thermal annealing was responsible, presumably, for the improvement of passivation capability.