| Summary: | 碩士 === 義守大學 === 電子工程學系 === 88 === Titanium dioxide (TiO2) thin films were reactively sputtered deposited on P+-type silicon substrate from a titanium dioxide target using Ar/O2 gas mixtures by reactive sputtering. The microstructural properties, conduction mechanisms, and reliability of sputtered TiO2 thin films treated by different rapid thermal annealing (RTA) at different temperatures in O2 atmosphere have been systematically investigated. Analytical results revealed that the leakage current decreases with the annealing temperature under the low RTA temperatures ( 550℃) and, contrarily, increases with the annealing temperature under high RTA temperatures (>550℃). The former result was examined and it was concluded that providing for a superior polycrystalline TiO2 film and reducing the oxygen vacancies. In addition, such the result leads the tunnel-limited Tunnel emission conduction (as-deposited and 300℃ RTA-treated samples) gradually transformed to electrode-limited Schottky emission conduction (450℃ and 550℃ RTA-treated samples). Furthermore, the latter result was suggested to increase due to generate the evident phenomenon of inferior structure, oxygen deficiency and more Si contamination, which to form transiting the Schottky emission conduction mechanism to Tunnel emission conduction process again. Finally, the time-dependent-dielectric-breakdown experiments revealed that 550℃-O2-RTA-treated TiO2 thin film possessed the superior crystallinity, creating fewer interfacial hole trapping states at the junction of TiO2/Si and exhibiting the best long-term reliability. Interestingly, the tendency of TDDB characteristics behavior of TiO2 thin films under different RTA temperatures is in accordance with those of the crystallinity variation and leakage current performance of TiO2 thin films, which provides worthy information that for samples possessing a superior crystallinity, a less leakage current as well as a better reliability will be reached.
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