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中文論文名稱 製備多孔性氮化鎵微米柱結構並利用機械式剝離技術製作高功率垂直式發光二極體之研究
英文論文名稱 A Study of Mechanical Lift-Off Technology for High-Efficiency Vertical LEDs by Using Micro-Porous GaN Template
校院名稱 淡江大學
系所名稱(中) 化學工程與材料工程學系碩士班
系所名稱(英) Department of Chemical and Materials Engineering
學年度 100
學期 2
出版年 101
研究生中文姓名 侯翔彬
研究生英文姓名 Hsiang-Pin Hou
電子信箱 gaobin5210@gmail.com
學號 699401120
學位類別 碩士
語文別 中文
口試日期 2012-05-25
論文頁數 67頁
口試委員 指導教授-許世杰
委員-許世杰
委員-劉正毓
委員-張正良
委員-吳宛玉
委員-黃建堯
中文關鍵字 機械式剝離  發光二極體  多孔性  氮化鎵 
英文關鍵字 mechanical lift-off  vertical LED  micro-porous  GaN  wet etching  wafer bonding 
學科別分類
中文摘要 本論文中主要探討製備多孔性氮化鎵微米柱結構,以利後續使用機械式剝離技術來去除導電性、散熱性皆不佳的藍寶石基板,以製作高功率垂直式氮化鎵發光二極體元件。我們欲使用此技術來取代目前業界常用的雷射剝離技術,以達到低成本、大量且快速生產的製程目的,並進而避免在雷射剝離時,高能量的雷射對氮化鎵薄膜表面產生永久性的破壞,導致後續製程的困難和發光效率的降低等問題。
首先我們利用高溫熔融態氫氧化鉀溶液,將氮化鎵及藍寶石基板之介面,蝕刻出多孔性氮化鎵結構之犧牲層,後續再藉由有機金屬化學氣相沉積,成長氮化鎵發光二極體之結構,最後使用晶圓鍵合的方式,利用矽基板與藍寶石基板之間熱膨脹係數的差異,以機械式剝離技術將藍寶石基板移除,並置換成導電、導熱性較高之矽基板,達成製作高功率垂直式氮化鎵發光二極體之目的。
我們發現平均線插排密度以穿透式電子顯微鏡測量後,從2×109 cm-2 降低至1×108 cm-2。故可藉由降低缺陷密度增加發光二極體元件之內部量子效率。此一研究不僅能開發新的高功率垂直式氮化鎵發光二極體元件製程技術,更期望能利用此一技術與業界結合,提供未來氮化鎵發光二極體元件製程的最佳選擇。
同時,我們也成功的製備380×380 μm2之晶粒,且在操作電流20 mA下,觀測到以機械式剝離技術製作而成的垂直式發光二極體,總輸出的光通量和傳統結構發光二極體相比增加了100%。證明以機械剝離技術代替雷射剝離技術置換藍寶石基板之方法確實可行,而且效果非常良好。
本論文成功整合我們所製備出來的多孔性氮化鎵微米柱結構犧牲層,藉由晶圓鍵合,使用機械式剝離技術移除低散熱性、低導電性之藍寶石基板,取代故有的傳統雷射剝離基板技術,可望解決在未來大面積晶圓級發光二極體的製程上所將面臨的困難與挑戰,此方法製程簡單且成本低廉,相當有利於應用在高亮度固態照明之領域。
英文摘要 We discuss the fabrication of mechanical lift-off high quality thin GaN with Micro-Porous GaN template for vertical light emitting diodes (V-LEDs). The Micro-Porous GaN templates were formed on the GaN/sapphire substrate interface under high temperature of 280℃ during 10 min molten KOH wet etching process. The average threading dislocation density (TDD) was estimated by transmission electron microscopy (TEM) and reduced from 2×109 to 1×108 cm−2.
Finally, the mechanical lift-off process is claimed to be successful by using the Micro-Porous GaN structures as a sacrificial layer during wafer bonding process.
The chip size was 380×380 μm2 and the electroluminescence (EL) intensity has shown significant 100% enhancement under operating current of 20 mA.
A vertical LED was successfully fabricated by using a mechanical lift-off method which is low cost and convenience. It is considered that these developments can lead solid-state lighting to the general lighting applications.
論文目次 目錄
誌謝..........................................................................................................Ⅰ
中文摘要..................................................................................................Ⅱ
英文摘要..................................................................................................Ⅳ
目錄..........................................................................................................Ⅴ
圖目錄......................................................................................................Ⅶ
表目錄......................................................................................................Ⅹ
第一章 前言............................................................................................1
1.1 氮化鎵發光二極體演進歷史.......................................................1
1.2 垂直式發光二極體之特性...........................................................5
1.3 研究動機.......................................................................................7
第二章 理論背景與文獻回顧..............................................................10
2.1 雷射剝離技術.............................................................................10
2.2 化學性剝離技術.........................................................................12
2.3 機械式剝離技術.........................................................................14
第三章 高功率垂直式發光二極體製備與量測..................................16
3.1 高功率垂直式發光二極體之製作流程.....................................16
3.2 溼式蝕刻製程制備多孔性氮化鎵微米柱結構.........................18
3.3 晶圓鍵合與機械式剝離技術之機制.........................................20
3.4 高功率垂直式發光二極體量測系統介紹.................................23
3.4.1 掃描式電子顯微鏡..............................................................23
3.4.2 穿透式電子顯微鏡..............................................................26
3.4.3 電致發光學量測系統..........................................................29
第四章 實驗結果分析與討論..............................................................31
4.1 氫氧化鉀溼式蝕刻.....................................................................31
4.2 氮化鎵晶格排列與氫氧化鉀蝕刻機制.....................................32
4.3 改變蝕刻參數對多孔性氮化鎵結構之影響分析與討論.........41
4.4 以多孔性氮化鎵結構再成長發光二極體之影響與討論.........47
4.5 以金-矽晶圓鍵合技術鍵合之討論............................................50
4.6 以機械式剝離技術製備垂直式發光二極體之影響與討論.....52
4.7 高功率垂直式發光二極體之光電特性分析與討論.................57
第五章 結論與未來展望......................................................................59
5.1 結論.............................................................................................59
5.2 未來展望.....................................................................................60
參考文獻..................................................................................................61
圖目錄
圖1.1 白光LED效率發展目標.................................................................3
圖1.2 發光二極體之應用.........................................................................4
圖1.3 氮化鎵與藍寶石基板晶格不匹配示意圖.....................................6
圖1.4 傳統打線式結構發光二極體受到電流聚集效應影響.................8
圖1.5 傳統發光二極體與垂直式發光二極體之比較.............................9
圖2.1 雷射剝離技術置換Si基板之製程示意圖....................................11
圖2.2 以AlN做犧牲層做化學剝離之製程示意圖...............................13
圖2.3 以AlN做犧牲層做化學剝離之製程示意圖...............................13
圖2.4 以CrN做犧牲層做化學剝離之製程示意圖................................13
圖3.1 本實驗之流程示意圖...................................................................17
圖3.2 熔融態氫氧化鉀溼式蝕刻制備多孔性氮化鎵結構...................19
圖3.3 金矽共晶相圖...............................................................................21
圖3.4 晶圓鍵合與機械式剝離技術之機制...........................................22
圖3.5 Hitachi S-4700I場發射掃描式電子顯微鏡之外觀.......................25
圖3.6 JEOL JEM-2010F場發射穿透式電子顯微鏡之外觀..............28
圖3.7 電致發光量測系統.......................................................................30
圖3.8 輻射耦合示意圖...........................................................................30
圖4.1 HCP 單位晶格:(a)原子位置單位晶格;(b)硬球單位晶格;(c)
隔離單位晶格..............................................................................32
圖4.2 氮化鎵Wurtzite結構排列............................................................33
圖4.3 氮化鎵之(a)晶體結構(b)單位晶胞..............................................33
圖4.4 Wurtzite結構之晶格面定義.........................................................34
圖4.5 氫氧化鉀蝕刻c-plane氮化鎵機制..............................................36
圖4.6 氫氧化鉀蝕刻m-plane氮化鎵機制.............................................38
圖4.7 氫氧化鉀蝕刻a-plane氮化鎵機制..............................................40
圖4.8 熔融態氫氧化鉀溶液以及溶於乙二醇之30%氫氧化鉀溶液對氮化鎵蝕刻速率示意圖..................................................................41
圖4.9 熔融態氫氧化鉀,蝕刻溫度280 ℃,時間3 min。(a)為上方俯視圖,(b)為變角度視角45度...........................................................42
圖4.10 Screw(α)、mixed(β)、edge(γ)三種不同缺陷型態之SEM圖.........43
圖4.11 Screw(α)、mixed(β)、edge(γ)三種不同缺陷型態之示意圖.........43
圖4.12 熔融態氫氧化鉀,蝕刻溫度280 ℃,時間5 min。(a)為上方俯視圖,(b)、(c)為不同區域變角度視角45度.................................44
圖4.13 熔融態氫氧化鉀,蝕刻溫度280 ℃,時間10 min。(a)為上方俯視圖,(b)為蝕刻孔洞大小,(c)為變角度視角45度.....................45
圖4.14 觀察再成長氮化鎵磊晶層線差排缺陷延伸之TEM側視.........48
圖4.15 於再成長之界面處產生缺陷彎曲迴圈之現象.........................48
圖4.16 再成長氮化鎵磊晶層於多孔性氮化鎵犧牲層側視圖.............49
圖4.17 本實驗所使用之石墨製具示意圖.............................................51
圖4.18 各種材料之屈服應力對溫度倒數作圖.....................................54
圖4.19 多孔性氮化鎵犧牲層結構表面之俯視圖.................................56
圖4.20 晶圓鍵合換成Si基板之後的側面圖........................................56
圖4.21 隨著操作電流增加對不同結構發光二極體的波長位移之比較..................................................................................................58
圖4.22 L-I-V量測不同結構及製備方式的發光二極體之比較............58
表目錄
表1.1 氮化鎵與藍寶石基板與鍵合之矽基板性質差異表.....................6
表2.1 剝離技術之比較...........................................................................15
表3.1 Hitachi S-4700I場發射掃瞄式電子顯微鏡重要規格..................24
表3.2 JEOL JEM-2010F場發射穿透式電子顯微鏡重要規格.........27
表4.1 石墨材料性質...............................................................................53
表4.2 Sapphire與GaN之性質差異表......................................................53
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