本文提出二種數值分析模式探討準分子雷射結晶技術製作多晶矽薄膜製程之凝固熱傳與結晶成核成長問題，第一種為巨觀模式，以熱源項處理雷射熱源，並使用等效比熱熱焓法處理相變化問題；第二種為巨微觀模式，以古典成核理論處理成核階段，使用介面反應函數處理成長階段，應用二階段修正模式處理晶粒侵犯階段，並以等效比熱熱焓法與熱源法處理相變化問題。數值方法採用有限差分法。在準分子雷射結晶製程中，由雷射能量密度與晶矽薄膜熔融態關係，可定義出三個矽晶成長的主要區域，這三個區域分別為部份熔融、接近完全熔融及完全熔融區域。它們能夠定義一個在接近完全熔融狀態關鍵的臨界能量密度，稱為完全熔融能量密度(Complete Melting Fluence又稱為Fc)，在Fc時，將產生相對的最大晶粒。本文數值模擬分析矽薄膜之最高溫度與最大熔化深度隨能量密度變化關係，並與實驗結果作比較驗證，二種模式皆相當正確地預測臨界能量密度(Fc)的值，這對使用準分子雷射製作多晶矽薄膜製程是相當重要的結果。由於直接量測脈衝雷射作用於矽薄膜的表面溫度與反射率的困難，本文以巨觀模式計算的矽薄膜表面反射率及以巨微觀模式計算的矽薄膜表面溫度與反射率和實驗量測比較分析，發現計算的結果合理地接近實驗結果，因此使用本文的模式分析可成功預測矽薄膜表面溫度與反射率變化，亦將節省實驗所需的人力與經費。製程中，不同熱緩衝層材料與薄膜之結構對工件溫度場的影響在文中一併探討。此部份之具體分析結果詳述於結論中，將有助於多層膜結構之設計與合適實驗工作條件的選擇。最後，本論文應用巨微觀模式具體分析矽薄膜之結晶成核成長問題並與實驗比對，除了可以正確求得Fc的值，並可成功預測矽薄膜於部份熔融與接近完全熔融區域之平均晶粒尺寸與熔化期間。驗證了在部份熔融與接近完全熔融區域，當能量密度愈大時(熔化期間愈長)，雷射照射之後的冷卻率會相對較低，過冷值與成長速率則相對較小，因此會使得晶粒密度相對較低，相對會產生較大的晶粒尺寸。由此可知，平均晶粒尺寸在部份熔融與接近完全熔融區域主要受過冷值與成長速率因素影響。本文並探討在完全熔融區域，均質成核與平均晶粒尺寸的關係，使用本文提出的均質成核數代入巨微觀模式計算，可成功預測矽薄膜於完全熔融區域之平均晶粒尺寸。

In this dissertation, the macro and macro-micro models are built to analyze the heat-transfer, solidification, nucleation and growth on the fabrication of poly-Si thin films using excimer laser crystallized technology. In these two models, the pulse energy of laser is treated as the source term in the energy equation, and the effective specific heat-enthalpy method and the source term scheme are used to handle the absorption and release of latent heat. For the macro-micro model, the classical nucleation theory and the interface response function are used to handle the nucleation and growth stages, respectively. The two-step Close-Pack model is applied in the impingement stage. The numerical method is finite difference method. Three main regimes are defined based on the energy density of laser and the melting state of Si thin films according to the fabrication of poly-Si thin films using excimer laser crystallized technology: partial, near complete, and complete melting. They can then define a critical fluence at near complete melting, which has been identified as the full-melt threshold (Fc). Largest grains are obtained at this Fc value. From the numerical analysis of maximum temperature and melt depth for different laser fluences, the threshold corresponding to the full melting of the Si film can be found. These critical fluences (full-melt threshold, Fc) obtained from the simulated results of the proposed two models agree fairly well with those from the experimental ones reported in the literature. The proposed two models could successfully predict the Fc which is important for the fabrication of poly-Si thin films using excimer laser crystallized technology. The surface temperature and reflectivity of silicon thin films after laser radiation are difficult to measure directly. In this work, the surface temperature of silicon films is numerically predicted from the macro model and this surface temperature and reflectivity of silicon films are also numerically computed via the macro-micro model. They agree reasonably well with those obtained from the experiments reported in the literature. Accordingly, our proposed models could successfully predict the surface temperature and reflectivity of silicon thin films. This approach then reduces manpower and expenditure of experiments. In addition, the effect of different buffer layers and the structure of thin films are also studied. The results are useful for the design of multi-layer structure and choices of feasible working conditions. They are reported in the conclusions. Eventually, the nucleation and growth of silicon thin films are analyzed by using the macro-micro model. The computed results are consistent with the experimental ones reported in the literature. In addition to Fc, the macro-micro model allows the accurate prediction of average grain sizes and melting duration of silicon thin films in the partial and near complete melting regimes. From the computational results, it can be verified that when the laser fluence is higher (the melting duration is longer), the cooling rate after laser irradiation is lower, the undercooling and growth velocity are smaller and the grain size is larger or the grain density is lower. Consequently, the average grain sizes are strongly dependent on the undercooling and growth velocity in the partial and near complete melting regimes. The relationship between homogeneous nucleation and average grain sizes in the complete melting regime are also investigated, and the homogeneous nucleation is applied in the macro-micro model. This proposed model could successfully predict the average grain sizes in the complete melting regime.

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