A study of yield improvement for TFT-LCD withcopper process
| Autor: | Jiang-Jin You, 游江津 |
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| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 In this study, the inverted-staggered thin film transistors were used to investigate the yield improvement of devices with copper process. We utilized the different metal materials that were deposited as the metal I electrode and different clean methods in metal surface before coating photo-resist, which improved the PEP I process defects,including the abnormal copper grain defect, the large disconnection defect of metal I, and the filamentous disconnection defect of metal I. Due to the poor performances of the copper film, including easy oxidization, diffusion, and poor adhesion on the glass, we proposed the improving methods. For the improvement of the abnormal copper grain defect of metal I, we deposited different metal materials, including CuOCu1Cu2 、 Cu 、 MoCuMo 、 MoCu 、 MoCu1Cu2 on the glass to find the optimization structure and material components of metal I. These results showed that a 96 Å thick Mo and a 5670 Å thick Cu exhibited the best performances. The MoCu film presented 2.8 nm mean roughness from the atomic force microscope measurement and there were no obvious grain boundary and oxygen signal on the surface, which were measured by SEM and EDS respectively. And the sheet resistance of Mo/Cu film was 0.041 Ω/□. From the pressure cook test and AAJET test, the Mo/Cu films had good adhesion on the glass substrate. The electrical characteristics of thin film transistors with various metal material as the gate electrodes showed no difference and the yield loss resulted from the thin film defects had been improved by the value of 9.2 %. For the improvements of the large disconnection defect and the filamentous disconnection defect of the metal I, its surface must be cleaned properly but could not be damaged. The experimental conditions were the various concentrations of TMAH developer solutions in the first cleaning tank, recycling or virgin deionized water in the second cleaning tank, and the different transport velocity and gas pressure in AAJET. The experimental results showed that 0.04 % TMAH developer solution in the first cleaning tank could reduce 58 degrees of contact angle in the metal I surface and no damage on the surface. The colony count of the cleaning tank was reduced to 4050 CFU/g. And the yield loss resulted from the photo-lithography defects had been improved by the value of 5.6%. Finally, the metal I of thin film transistor was fabricated by the combinations of the optimized conditions of thin film and photo-lithography processes exhibited the yield of 93.5% before laser repair. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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