Characterization of TiN/TiSi2 bilayer for application to ULSI |
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Authors: | Cheol-Jin Lee Yung-Kwon Sung |
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Affiliation: | (1) Department of Electrical Engineering, Korea University, 1, 5-Ka, Anam-Dong, Sungbuk-Ku, Seoul, Korea |
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Abstract: | The properties of TiN/TiSi2 bilayer formed by rapid thermal annealing (RTA) in an NH3 ambient after the titanium film is deposited on the silicon substrate is investigated. It is found that the formation of
TiN/TiSi2 bilayer depends on the RTA temperature and a competitive reaction for the TiN/TiSi2 bilayer occurs at 600°C. Both the TiN and TiSi2 layers represent titanium-rich films at 600°C anneal. The TiN layer has a stable structure at 700°C anneal while the TiSi2 layer has C49 and C54 phase. Both the TiN and TiSi2 layers have stable structures and stoichiometries at 800°C anneal. When the TiN/TiSi2 bilayer is formed, the redistribution of boron atoms within the TiSi2 layer gets active as the anneal temperature is increased. According to secondary ion mass spectroscopy analysis, boron atoms
pile up within the TiN layer and at the TiSi2−Si interface. The electrical properties for n+ and p+ contacts are investigated. The n+ contact resistance increases slightly with increasing annealing temperature but the p+ contact resistance decreases. The leakage current indicates degradation of the contact at high annealing temperature for
both n+ and p+ junctions. |
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Keywords: | Contact barrier metal competitive reaction rapid thermal annealing TiN/TiSi2 bilayer |
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