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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/65992

    Title: MOCVD旋轉載台結構應力與晶圓翹曲分析;Analysis of Structural Stress in Susceptor and Warpage of Film-Substrate Systems for an MOCVD Reactor
    Authors: 郭書瑋;Guo,Shu-Wei
    Contributors: 機械工程學系
    Keywords: 有機金屬化學氣相沉積;晶圓翹曲;MOCVD;Wafer bow
    Date: 2014-08-25
    Issue Date: 2014-10-15 17:20:15 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本研究目的在透過有限元素分析(FEM),計算一有機金屬氣相沉積(MOCVD)反應腔體之旋轉載台在製程時受到高溫熱負載及不同轉速作用時的應力分佈與變形。考慮的負荷條件分別為無轉速只受溫度負載之狀態,以及主軸轉速10 rpm、100 rpm、500 rpm、1000 rpm、1500 rpm之情況。另外,本研究亦以系統化觀點考慮整個旋轉載台的溫度分布對氮化鎵薄膜磊晶翹曲及薄膜殘留應力的影響。此外,本研究亦以簡易模型分析不同晶圓直徑與材料、不同薄膜與晶圓厚度、加入緩衝層與否及溫度梯度對於晶圓翹曲及氮化鎵薄膜殘留應力的影響。為驗證本研究所建立有限元素分析模型之有效性,將模擬結果與前人以不同厚度氮化鎵磊晶在藍寶石晶圓量測實驗結果作比對,模擬結果之晶圓翹曲及晶圓曲率半徑改變趨勢和實驗結果一致,證實本研究所建立模型之有效性,可適用於評估各種磊晶參數對於晶圓翹曲及薄膜殘留應力的影響。
    ;The aim of this work is using finite element analysis (FEM) to study the effects of thermal load and rotation speed on the structural integrity of a substrate holder module in an MOCVD reaction chamber. Several loading conditions are considered, including thermal load alone and thermal load plus rotation speeds of 10 rpm, 100 rpm, 500 rpm, 1000 rpm, and 1500 rpm. In addition, the wafer bow and residual stress of GaN growth on silicon or sapphire are systematically studied for various scenarios. The effects of size and material of wafer, thickness of film and substrate, buffer layer, and temperature gradient are characterized. Moreover, in order to validate the FEM model constructed in the current study, experimental results of a previous study are applied to assessing the credibility of the numerical methods by comparison of the simulation results with the experimental measurements of wafer bow. The variation trends of wafer bow and curvature radius in simulation agree well with those in experiment such that the constructed model is validated. Therefore, the constructed model is effective in assessing the effect of various parameters acting on a film-substrate system.
    As the calculated critical stress is less than the strength of material, no structural failure is predicted for all the components in the given substrate holder module under all of the given loading conditions. The variation of critical stress with rotation speed in all of the components is small. Given a similar heat source in the MOCVD reaction chamber, temperature of the upper components such as susceptor, substrate holders, and wafers is higher in the case of sapphire wafer than that in the case of silicon wafer. The temperature gradient of upper components is greater for the silicon wafer case. A greater temperature gradient in the film-substrate system generates a greater wafer bow and residual stress. Therefore, the temperature uniformity is an important parameter for the epitaxial process. The sign of residual stress is different between a GaN film grown on a sapphire wafer and a silicon wafer (compressive for sapphire wafer and tensile for silicon wafer). For growing a GaN thin film, GaN thin film, sapphire wafer is better than silicon wafer in terms of lessening cracking in film.
    No matter GaN is grown on sapphire wafer or silicon wafer, wafer bow increases and residual stress in the film decreases with an increase in thickness of film. Increasing the thickness of wafer can effectively reduce wafer bow, which is also a method commonly used in industry, but the residual stress in the film is increased. Given a wafer thickness, the size of bow is increased with wafer diameter, which is one of the major challenges in growth of a large-size epitaxial wafer. The magnitude of residual stress in a thin film can be reduced when a thick buffer layer is added between film and wafer. For a lower residual stress, the reliability of a thin film can be improved by the addition of buffer layer.
    Appears in Collections:[機械工程研究所] 博碩士論文

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