目前氮化鎵(GaN)發光二極體(LED)的主要生成方式為在藍寶石晶圓上透過有機金屬氣相沉積(MOCVD)使其磊晶GaN薄膜。由於磊晶腔體內的零組件配置與加熱器設計等因素會影響晶圓表面溫度均勻度以及晶圓翹曲等問題。本研究利用有限元素法計算在MOCVD反應腔體中承載盤與晶圓的表面溫度分布以及由於晶圓表面溫度分布不均勻所產生的熱應力和薄膜與晶圓熱膨脹係數不匹配所導致的晶圓翹曲量，探討承載盤設計對晶圓與GaN薄膜上的溫度分布及晶圓翹曲的影響。 本研究先利用有限元素法計算承載盤在腔體內受石墨加熱器加熱後的載盤表面溫度分布，並利用實驗驗證分析結果的可靠度，再進一步計算晶圓放置於承載盤上受加熱後的晶圓表面溫度，並與實驗量測結果比對驗證，確認模擬結果的有效性。本研究也根據晶圓放置於未改良設計之承載盤上的晶圓表面溫度分布，設計一凹槽載盤，將凹槽建立在載盤底部及晶圓槽底部，藉此改變承載盤內部熱傳及承載盤與晶圓之間的熱傳條件，以提升晶圓表面的均溫性，進而提升GaN薄膜磊晶品質。經比對計算與實驗結果，發現量測承載盤表面與晶圓表面溫度分布結果與模擬分析結果的誤差百分比皆小於5%，證實本研究所建立計算模型的有效性及便利性。本研究同時也計算晶圓放置於未改良設計之承載盤與改良設計之凹槽承載盤磊晶GaN薄膜後，系統降至室溫的晶圓翹曲量，模擬分析結果顯示，藉由改善晶圓表面的溫度梯度可以有效地降低晶圓與薄膜系統冷卻至室溫的晶圓翹曲量。 ;Metal organic chemical vapor deposition (MOCVD) process is a technology in fabrication of GaN-based optoelectronic devices, such as LEDs. The substrate for growing GaN thin film is usually sapphire. Temperature distribution on the substrate surface is affected by the component and heater configuration in the MOCVD reaction chamber. In addition, wafer warpage is an issue in MOCVD process. The aim of this work is using finite element method (FEM) to systematically calculate the temperature distribution on the surface of susceptor and wafer substrate. Wafer warpage induced by mismatch in coefficient of thermal expansion between substrate and thin film is also investigated. Temperature distribution on the surface of susceptor and wafer substrate in a given MOCVD reactor is calculated by FEM simulation and measured in experiment. According to the temperature distribution on the wafer substrate placed on an original, plain susceptor, designed grooves are made on the back side of susceptor and on the bottom surface of wafer pockets to improve temperature uniformity on the wafer substrate by changing heat transfer conditions in the susceptor and between susceptor and wafer substrate. By doing so, it is expected to produce a better-quality film. Temperature difference in percentage between simulations and experimental results is less than 5%. Effectiveness of the constructed FEM model is validated by such a good agreement between simulations and experimental measurements. Warpage of wafer placed on plain susceptor and on grooved susceptor is also investigated in this study. Simulation results indicate the wafer warpage is effectively reduced by improving temperature uniformity on the wafer substrate through the groove design in susceptor.
