在有機金屬氣相沉積 (MOCVD)反應的實際長晶過程中，由於加熱器的配置會產生晶圓表面溫度分布不均與晶圓翹曲的問題，本研究利用有限元素分析法(FEM)，計算晶圓表面在長晶過程中的溫度分布與薄膜成長後系統降至常溫的晶圓翹曲量，探討承載盤及晶圓的溫度分布對於氮化鎵薄膜磊晶品質及薄膜翹曲的影響。 考慮一般業界經驗，要獲得品質良好的薄膜，長晶時晶圓表面最大溫差必須小於1 K；本研究藉由改變晶圓及承載盤部分區域之間的熱傳條件來設計承載盤，以實現使2吋及8吋晶圓表面溫度更均勻，並且減少2吋晶圓在製程後降至常溫之翹曲量的目的。此外，亦考慮由於晶圓放置誤差造成溫度輸入或接觸狀況改變，對於晶圓表面在長晶階段的溫度分布及常溫時晶圓翹曲量之影響。同時藉由前人以不同厚度氮化鎵磊晶在藍寶石晶圓的翹曲量測實驗與本研究的模擬結果做比對，確認模擬結果之晶圓翹曲及晶圓曲率半徑與相對應的實驗結果十分接近，驗證本研究所建立模型的有效性，故可適用於預測晶圓表面在長晶階段的溫度分布及常溫時的翹曲量。 本研究先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，考慮將設計的凹槽建立在晶圓高溫區域下方的承載盤支撐面上，藉此改變承載盤與晶圓之間的熱傳條件，讓晶圓表面高溫區域的溫度降低，以此方式降低2吋晶圓表面溫度差及翹曲量。將此設計應用於8吋晶圓的承載盤上也再次證明了本研究的凹槽設計可以有效地降低晶圓表面在長晶階段時的溫度差，也能容忍一定程度的溫度輸入偏差，包括溫度輸入大於或小於原本的值2 K、溫度輸入分布沿徑向遠離或靠近旋轉中心、較大的溫度輸入差等。 本研究也同時結合了2吋反向預翹曲晶圓及具有相同彎曲形狀支撐面及凹槽的承載盤，使晶圓於長晶時的表面溫度小於1 K，同時也幾乎消弭了原本在常溫時的翹曲量。但是由於預翹曲的晶圓與彎曲支撐面之間的接觸狀況對於晶圓表面在長晶時的溫度較敏感，若因製造上的誤差使兩曲面之曲率相異而造成非接觸的區域過大，其改善效果則會受到限制。 ;The aim of this work is using finite element analysis (FEM) to systematically study the temperature distribution at operation stage and warpage at shutdown stage on the top surface of wafer in MOCVD process. The effects of temperature input and substrate holder design are considered. According to industrial practice, it is acceptable that the maximum temperature difference on the wafer surface is less than 1 K. Groove designs are applied on the substrate holder to improve the thermal conditions for a better temperature uniformity at operation stage and smaller warpage on the wafer at shutdown stage. In addition, the combined effects of initial wafer bow and groove design for substrate holder are also investigated. A reasonable agreement of the simulations with the previous experimental measurements validates the constructed FEM model which is effective in assessment of the temperature distribution and warpage on the wafer surface in the film-substrate system of MOCVD. According to the temperature distribution on the wafer surface placed on an original, plain 2-in substrate holder, designed grooves are made on the supporting surface of a modified substrate holder and improve the temperature uniformity with a maximum temperature difference less than 1 K. The wafer bow is also reduced by such groove designs. A similar approach is also applied to an 8-in substrate holder and effectively reduces the maximum temperature difference on the wafer at operation stage. The 2-in grooved substrate holder is capable of tolerating the given temperature deviations for a maximum temperature difference on the wafer surface to be less than or around 1 K, such as changing the temperature input with a slight increment or decrement, shifting the temperature input curve toward or away from the center of the susceptor, and enlarging the temperature difference in the temperature input. The combination of a 2-in bow wafer with a substrate holder having a curved supporting surface and designed grooves effectively makes the temperature difference at operation stage on the wafer surface less than 1 K and almost eliminates the warpage of wafer at shutdown stage. However, the design for a bow wafer working together a curved substrate holder with designed grooves is sensitive to the contact condition between bow wafer and substrate holder.
