外加cusp磁場柴氏法生長單晶矽之熱流場及氧雜質傳輸數值分析

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/60795

Title:	外加cusp磁場柴氏法生長單晶矽之熱流場及氧雜質傳輸數值分析
Authors:	郭沛瑾;Guo,Pei-Chin
Contributors:	能源工程研究所
Keywords:	單晶矽;磁控柴氏長晶法;外加cusp磁場;氧雜質;Silicon single crystal;Magnetic Czochralski crystal growth method;Cusp magnetic field;Oxygen impurity
Date:	2013-07-26
Issue Date:	2013-08-22 12:03:10 (UTC+8)
Publisher:	國立中央大學
Abstract:	單晶矽可用於矽基太陽能電池、半導體積體電路等之基材，單晶矽中氧雜質濃度是主要影響太陽能電池壽命及半導體元件效率的因素之一。傳統柴氏長晶法中，可經由控制晶堝轉、氬氣流速、安裝熱遮罩等方法，來改變熔湯流動型態，而控制氧雜質。由於矽為半導體，以外加磁場之羅倫茲力，亦可影響熔湯流動，而且此方法長成之晶體，氧濃度可低於傳統柴氏長晶法，本研究以數值模擬方法，分析單晶矽在外加cusp磁場作用下，磁場作用於熔湯的機制與原理，並探討生長參數、磁控變因的調整下，熔湯熱場分布及對晶體氧雜質含量的影響，以生成低含氧量單晶矽。本研究中首先以模擬了解cusp磁場在矽熔湯中的作用方式，磁場與半導體矽作用形成羅倫茲力，熔湯流動受反向之羅倫茲力抑制穩定，氧雜質被抑制於堝壁。接著探討在cusp磁場作用下生長參數改變的影響，流動受晶轉影響小，而堝轉可明顯改變流動，且降氧效果好；改變熱遮罩與熔湯液面距離、熱遮罩形狀及氬氣流率，欲縮小影響氧雜質蒸發率的剪力流，增加液面上方氧化矽的傳輸率，發現剪力流的變動及二次流的生成為影響熔湯流動及質傳的主因，不利於氧雜質的控制。另討論cusp磁場特性零高斯面，本研究的最佳零高斯面位於自由液面下25mm處，此時流動結構受磁場影響，氧雜質分佈達到一最佳狀態。最後探討長晶過程cusp磁場下生長單晶矽晶棒之軸向氧濃度分佈的均勻性，發現以堝轉配合磁場強度作修正可得較均勻之矽晶棒軸向氧濃度分佈。本研究模擬分析磁控CZ法法單晶矽之生長機制，找出磁控參數對晶體生長的影響及雜質分佈效應，並作生長參數調整控制。外加cusp磁場有助於控制氧雜質濃度，幫助改善磁控法生長矽單晶製程，提升生產良率達到低含氧量單晶矽之目標。 Silicon single crystal is the substrate of silicon based solar cell, semiconductor and so on. The oxygen impurity in the silicon single crystal is the main effect factor for solar cell lifetime and the efficiency of semiconductor devices. In Czochralski silicon crystal growth, it can change flow convection to control oxygen impurity transportation by following ways like crystal/crucible rotation control, argon flowrate and install heat shield. Because silicon is magnetic, the silicon melt flow convection can effect by Lorentz force which produce from additional magnetic. This grown silicon crystal under magnetic field can get lower oxygen concentration than traditional Czochralski method. This thesis use numerical simulation to analysis the mechanism under cusp magnetic field in silicon melt convection of crystal growth. Under the adjust of growth parameter or magnetic factor, we investigate the distribution of thermal, temperature and oxygen impurity to grow lower oxygen concentration content silicon single crystal. First, through simulation to understand the principle of cusp magnetic field in silicon melt. Magnetic field and magnetic silicon can produce Lorentz force. The flow convection suppressed by counter Lorentz force become stable and restrain oxygen impurity on crucible wall. Second, we investigate the effect of growth parameter under cusp magnetic field. Crucible rotation changes flow pattern obviously than crystal rotation and get lower oxygen concentration. To shrink the stress flow which effects the evaporation of oxygen, we change the gap of heat shield and melt free surface, heat shield shape and argon flowrate, to increase SiO transmission rate where above melt surface. We found stress flow and secondary flow are adverse effects on flow convection and impurity transportation for oxygen impurity control. We also discuss Zero Gauss Plane, a characteristic of cusp magnetic field the best position in this furnace is under melt surface 25mm. The magnetic influent flow structure makes the oxygen distribution at a best state. Final, discuss the grown silicon single crystal axial oxygen concentration uniformity under cusp magnetic field. We found through adjust of crucible rotation together with magnetic strength can get more homogeneous crystal axial oxygen concentration distribution. This thesis analysis silicon single crystal growth mechanism under magnetic Czochralski method, find the effects of crystal growth, impurity distribution by magnetron parameter and by the control of growth parameters. Using cusp magnetic field is helpful to control oxygen impurity concentration and improve magnetron method crystal growth process. Magnetic Czochralski method increase the production yield and reach the aim of low oxygen concentration content silicon single crystal.
Appears in Collections:	[Energy of Mechatronics] Electronic Thesis & Dissertation

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