Enhanced thermal stability of a sputtered titanium-nitride film as a diffusion barrier for capacitor-bottom electrodes |
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Authors: | Dong-Soo Yoon Jae Sung Roh Sung-Man Lee Hong Koo Baik |
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Affiliation: | (1) Advanced Process-Capacitor, Memory Research & Development Division, Hynix Semiconductor Inc., 467-701 Kyoungki-do, Korea;(2) Department of Advanced Material Science and Engineering, Kangwon National University, Chuncheon, 200-701 Kangwon-do, South Korea;(3) Department of Metallurgical Engineering, Yonsei University, 120-749 Seoul, South Korea |
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Abstract: | The effect of a thin RuOx layer formed on the Ru/TiN/doped poly-Si/Si stack structure was compared with that on the RuOx/TiN/doped poly-Si/Si stack structure over the post-deposition annealing temperature ranges of 450–600°C. The Ru/TiN/poly-Si/Si contact system exhibited linear behavior at forward bias with a small increase in the total resistance up to 600°C. The RuOx/TiN/poly-Si/Si contact system exhibited nonlinear characteristics under forward bias at 450°C, which is attributed to no formation of a thin RuOx layer at the RuOx surface and porous-amorphous microstructure. In the former case, the addition of oxygen at the surface layer of the Ru film by pre-annealing leads to the formation of a thin RuOx layer and chemically strong Ru-O bonds. This results from the retardation of oxygen diffusion caused by the discontinuity of diffusion paths. In particular, the RuOx layer in a nonstoichiometric state is changed to the RuO2-crystalline phase in a stoichiometric state after post-deposition annealing; this phase can act as an oxygen-capture layer. Therefore, it appears that the electrical properties of the Ru/TiN/poly-Si/Si contact system are better than those of the RuOx/TiN/poly-Si/Si contact system. |
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Keywords: | Thin RuOx layer thermal stability TiN diffusion barrier oxygen diffusion |
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