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1	Fabrication process assessment and negative bias illumination stress study of IGZO and ZTO TFTs Hoshino, Ken 11 June 2012 (has links) Indium-gallium-zinc oxide (IGZO) and zinc-tin oxide (ZTO) are investigated for thin-film transistor (TFT) applications. Negative bias illumination stress (NBIS) is employed for electrical stability assessment. Unpassivated IGZO and ZTO TFTs suffer from severe NBIS instabilities. Zinc-tin-silicon oxide is found to be an effective passivation layer for IGZO and ZTO TFTs, significantly improving the NBIS stability. NBIS instabilities in unpassivated TFTs are attributed to an NBIS-induced desorption of chemisorbed oxygen from the channel layer top surface, exposing surface oxygen vacancies. A ZTSO layer protects the channel layer top surface from adsorbed gas interactions and also appears to reduce the density of oxygen vacancies. The best device architectures investigated with respect to TFT electrical performance are found to be staggered with aluminum electrodes for unpassivated TFTs and coplanar with ITO electrodes for ZTSO-passivated TFTs. Annealing in wet-O₂ is not found to be effective for improving the performance of IGZO or ZTO TFTs or for reducing the post-deposition annealing temperature. / Graduation date: 2012 IGZO ZTO TFT Stability Indium gallium zinc oxide zinc tin oxide ZTSO zinc tin silicon oxide TFT structure wet oxidation dry oxidation water contamination NBIS negative bias illumination stress Thin film transistors Zinc tin oxide Indium compounds Gallium compounds

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Fabrication process assessment and negative bias illumination stress study of IGZO and ZTO TFTs