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Please use this identifier to cite or link to this item: http://ir.hwai.edu.tw:8080/ir/handle/310996100Q/1358

Title: 各種沉入式加熱器對垂直布利基曼長晶爐內長晶過程影響之研究
A Study for the Effects at Various Parameters of a Submerged Heater on a Vertical Bridgman Crystal Growth
Authors: 莊書豪
Keywords: 垂直布利基曼法
沉入式加熱器
多孔式加熱器
釔鋁石榴石
Vertical Bridgman
Submerged heater
Porosity heater
YAG
Date: 2010-07
Issue Date: 2010-09-24 11:50:23 (UTC+8)
Abstract: 垂直布利基曼長晶法(Vertical Bridgman Crystal Growth,VB)是釔鋁石榴石 (Y3Al5O12;YAG)製造光電半導體單晶的主要方法之一。布利基曼長晶法的優點在於密閉空間遭受污染情況較少,晶體靜止產生的熱應力相對較小。晶體長晶主要受制於固液界面的曲率,ㄧ般而言,固液界面曲率愈小(或半徑愈大)其晶體缺陷愈小。因此,如何控制長晶爐內流場流動及流場強度等參數對其長晶速度是有相當重要的關係。由於有關文獻對垂直布利基曼長晶爐中置入加熱器之研究並不多,本計畫擬針對置入各種沉入式加熱器深入完整研究其對垂直布利基曼長晶爐長晶的性能影響,這就是本計劃的動機。本計畫研究的目的為在垂直布利基曼長晶爐中,置入沉入式加熱器,看此加熱器對其長晶的影響,並分析加熱器形狀(柱狀與圓盤狀)、尺寸(Rh/Rc=1/4~3/4,其中 Rh為加熱器半徑,Rc為安瓿管內側半徑)、位置(d/Rc,其中d為加熱器底部與液界面距離)與多孔性對長晶過程的最佳化參數。本計畫擬分為三年期的計畫。第一年(1/3)對各種Nd:YAG(Nd在Y3Al5O12中的滲雜) 在垂直布利基曼長晶爐中的生長過程,研究模擬置入加熱器前後看看其對長晶過程的影響,其中所得到的數值結果包括速度場、溫度場、濃度場的分布,藉由這些物理性質分佈以瞭解沉入式加熱器對垂直布利基曼長晶爐長晶過程的控制參數。研究方法擬從液態金屬凝固界面模擬與垂直布利基曼長晶爐生長過程模擬等兩方面來進行。首先以低熔點的金屬鎵(熔點29.78℃)模擬其金屬凝固界面形狀的變化並與現有文獻作比較[17],以驗證本計畫模型的正確性。接著考慮在安瓿管內YAG(熔點2243℃)之熔體內置入加熱器,研究其所造成的流場流動及凝固界面形狀的變化情形。第一年所模擬的結果將與現有文獻 [ 17] 作比較,以驗證其正確性。此結果將提供本計畫第二年、第三年在垂直布利基曼長晶爐中改變沉入式加熱器形狀及大小與置換為多孔性加熱器的參考。第二年(2/3)計畫為在原先的垂直布利基曼長晶爐長晶生長過程中,改變沉入式加熱器的外型形狀(柱狀與圓盤狀)、尺寸(本計劃所欲模擬尺寸為Rh/Rc=1/4~3/4,其中Rh為加熱器半徑,Rc為安瓿管內側半徑)與位置(d/Rc,其中d為加熱器底部與液界面距離)等參數,以瞭解此加熱器參數對長晶過程的影響,並找出其最佳化參數。本研究方法為數值方法。假設為軸對稱、忽略毛細管現象、安瓿管與爐壁間的熱交換以假設安瓿管外側的溫度分佈。採用固定網格及有限體積的有限差分法,在能量方程式中凝固熱的釋放以等效熱焓表示。分析數值模擬結果,並找出各種加熱器形狀及其半徑與安瓿管內徑比 (Rh/Rc)、加熱器底部與固液面間距離和安瓿管內徑的大小比(d/Rc)等參數對垂直布利基曼長晶過程之最佳化的參數組合,以提供業界的參考。第三年(3/3)延續第二年所開發的垂直布利基曼長晶爐置入沉入式加熱器的形狀與尺寸結構,並將其改為沉入式多孔性加熱器(本年度所欲研究的設計參數包括:多孔性的體積比、大小、擺放位置等)。研究方法亦為數值模擬。所得結果將與第二年沉入式加熱器之結果比較,分析當所置入的沉入式加熱器改為沉入式多孔性加熱器時其對布利基曼爐流場與固液界面的影響,並比較它們之間對長晶性能的優缺點,以提供業界的參考。本計畫多孔性加熱器材質擬採用鐵基的(Fe–Cr–Al)合金,因它具有重量輕、成本低廉及整個爐管內加熱均勻的優點。當本計畫三年期之全程計畫完成後,預期可以提出垂直布利基曼長晶爐對YAG 光電晶體在長晶過程中,如何降低固液曲面曲率、降低流線函數等重要控制參數的成果。此成果除了可以提供半導體相關業界上的參考,並能提昇國內的學術研發能力。
The Vertical Bridgman(VB) Crystal Growth is a mainly method of making photoelectricity semiconductor crystal (Y3Al5O12, YAG). The crystalloid solution grows gradually into the crystallization state. The merits of VB are that the small airtight spatial pollution is decreased, the crystal produces the static thermal stress is relatively small, and the wafer size crystal growth can be larger when the defect of liquid-solid contact surface curvature is allowance. Therefore, the control flow field crystal, flow intensity and direction in the VB is an important factor. The first year of this project (1/3), we will establish the complete crystal growth process of Nd: YAG (Nd dopting in Y3Al5O12) pour into the vertical Bridgman (VB).The results will be shown as the distributions of velocity field, the temperature field, and the density. And, we will discuss and provide the influence factor or parameters for the crystal growth process of YAG into the VB. The research technique is from the simulation of liquid metal coagulation contact surface and the growth process of VB. we first use the low melting of metal Ga to simulate the metal coagulation interface profile, and comparing the related references to confirm the correct of the simulated model. Then, we add the submerged heater on the VB and to analyze the effects of submerged heater on a VB flow field. Then, the heat transfer (conduction, convection, and radiation) between awpoule tube and YAG are calculated and analyzed. These results will provide the next year of project work. The second year of this project (2/3) is study for the effects of a various submerged heater parameters on a vertical Bridgman. The parameters of this project are the ratios of submerged heater radius to inside radius of Ampoule tube(Rh/Rc), the ratios of distance between bottom of submerged heater and interface of solid-liquid to the radius of Ampoule tube(d/Rc). The governing equations are assumped the axial symmetry, neglect capillary phenomenon, and the heat exchange between Ampoule tube and wall is obtained from the outside temperature distribution of Ampoule tube. The numerical method uses the fixed grids and finite difference of finite volume. The energy equation for releasing condensation energy is used by the Voller’s equivalence enthalpy. The results will analyze and discuss to find the best parameters for YAG crystal growth process in the VB. The third year of this project (3/3) is continued the second year work. The main purpose of this year is changed the structure of submerged heater. The structure of submerged heater in this year project is changed from solid state to the porous profile. The study parameters are heater porous volume ratio, and heater position. The numerical simulation is also used to simulate this field of porous submerged heater on VB flow field. The results will compare and analyze with the solid submerged heater (2nd year). The effects of porous material of submerged heater on VB flow field and interface of between solid and liquid will be shown and discussed. The porous heater for ferric redical alloy (Fe-Cr-Al) are used due to the advantages of the light weight, cheap cost, and uniform for heating (as shown in Figure 5). As the 3 years project is completed, we will provide the controlled parameters, as the velocity of crystal growth, the curvature of solid-liquid interface, and the stream function of crystal growth process to YAG photoelectricity crystal on a VB. The results are also providing a reference for the domestic related semiconductor industry and promote academic research and development.
Appears in Collections:[職業安全衛生系暨碩士班] 研究計劃

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