| Summary: | 碩士 === 國防大學中正理工學院 === 兵器系統工程研究所 === 94 === The processes commonly used to fabricate poly-silicon (poly-Si) thin films by recrystallization technique can roughly be categorized as Solid Phase Crystallization (SPC)-- superior in achieving film crystallinity, Metal-Induced Crystallization (MIC)-- relatively better in the obtained grain size, and Excimer Laser Annealing (ELA)-- advantageous in improving film’s electron mobility. In view of the fact that SPC has to be carried out at a much higher temperature than the other processes and the ELA process has a rather high initial/running cost, this research aimed, on the basis of MIC process, to develop a low-cost process which is suitable for large-area panel processing by adopting sputtering and furnace annealing techniques. The effects of the thickness of Ni coating and annealing parameters such as processing temperature, time, and chamber’s atmosphere on the microstructure and electrical properties of the obtained film were systematically investigated.
The results showed that nickel-induced crystallization of amorphous silicon thin films could be achieved in the air at an annealing temperature of 500℃ or 550℃ for more than 10hrs or 5hrs respectively and an average grain size around 320nm was observed. Given the same annealing parameters, thicker Ni coating could generate larger grains by minimizing the negative aspect introduced by surface oxidation. The electrical resistance of the obtained poly-Si film was found to be decreasing by reducing the thickness of Ni coating and/or increasing the annealing time and temperature. Based on the obtained results of this study, the recommended MIC process conditions in air are as followed: a Ni layer of 4nm or thicker is deposited on the amorphous silicon which is then annealed at 500℃ or 550℃ for 10~20hrs or 5~10hrs respectively to achieve the nickel-induced crystallization. A model describing the procedure/mechanism of nickel-induced crystallization was also developed in this research by analyzing and summarizing the obtained results.
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