電磁式感應加熱柴氏法生長氧化鋁單晶過程之數值模擬分析; Numerical simulation during an inductively heated Czochralski sapphire crystal growth system

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题名:	電磁式感應加熱柴氏法生長氧化鋁單晶過程之數值模擬分析;Numerical simulation during an inductively heated Czochralski sapphire crystal growth system
作者:	朱信旗;Hsin-chi Chu
贡献者:	機械工程研究所
关键词:	柴氏法;晶體生長;氧化鋁單晶;數值模擬;Czochralski;crystal growth;sapphire;Numerical simulation
日期:	2008-01-17
上传时间:	2009-09-21 12:00:37 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	柴氏單晶生長法(Czochralski single crystal growth method)又稱提拉法，是目前生長氧化鋁單晶（Sapphire）最經濟也最常使用的方法。為能確保生長sapphire單晶的品質及掌握坩堝內熔湯之生長情況，因此使用有限元素法（FEM）為基礎的COMSOL Multiphysics軟體來進行電磁場、熱場及流場三場耦合之柴氏生長氧化鋁單晶過程的數值分析模擬，以獲得熔湯內之熱流場分佈情形及相關資訊。本研究主要探討CZ法生長氧化鋁單晶過程中以電磁場感應加熱的方式分析坩堝內的熔湯之熱流場的分佈情形。從未長晶階段到不同長晶過程逐一進行模擬並探討流場內及晶體固液界面形態的變化，包括調整感應電流及加熱線圈位置改變的影響。分析影響熔湯內熱流場分佈的各項製程的重要因素。希望透過完整的分析模擬，將整個長晶過程一一呈現。模擬結果探討氧化鋁單晶生長過程中調降加熱線圈的電流量，熔湯內部溫度分佈等溫線及速度場會趨於緩和。且因為晶體生長長度增加，晶體會帶走較多的能量，使得固液界面曲率增加會更凸向熔湯。最後探討調整加熱線圈位置的影響，加熱線圈產生的感應磁場中心接近坩堝中間位置時，加熱坩堝內氧化鋁熔湯達適當溫度時所需的能量最小。這些分析結果將可作為柴氏長晶系統生長氧化鋁單晶時之重要參考指標，並可為將來深入研究單晶生長機制的基礎。 Sapphire single crystals are widely used in variety of modern high- tech applications. Among crystal growth methods, the Czochralski single crystal growth method is a good commercial method for growing the larger, high-optical-quality sapphire crystal. The finite element software COMSOL Multiphysics is employed to simulate the melt temperature and velocity distribution during an inductively heated of sapphire crystal growth process using CZ. Temperature and velocity field in an inductively heated Czochralski crystal growth furnace is investigated numerically during the different crystal growth stage (from 25 to 125mm). The temperature and flow field inside the furnace was calculated coupled with the heat generation of the Ir crucible that was induced by the electromagnetic field (supported by the RF coil). The heat loss from the free surface and the crystal are due to thermal radiations which are calculated by the emissivity, the Gebhart factor and temperature of the furnace surface. The results show that the temperature distributions of the melt and crystal are affected by the relative position between crucible and induction coil due to the modification of the electromagnetic field in the CZ furnace. The shape of solid-melt interface is also affected by the radiation of the crystal surface. Therefore, the growth parameters such as the position of RF coil, the growth length of crystal and the surface tension etc.; will be investigated in the present study.
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