臺灣博碩士論文加值系統

本論文使用半導體激發固體雷射器雷射刻劃(Scribe)紫外光覆晶型LED以提升發光效率。使用雷射刻劃以提升亮度的概念源自於圖形化藍寶石基板表面的微米圖形結構，因為此微米結構有利於提高光萃取效率，所以本研究目標使用雷射刻劃出切深深度小於3 μm的角錐狀圖形，再利用機台刻劃出棋盤式圖形，並研究間距不同的圖形是否具有亮度差異。
為使用雷射刻劃出微米結構的角錐狀圖形，需將機台參數能量調整為低能量(0.3 W)、高切速(120 mm/s)的極端狀況，但藍寶石基板在此條件下吸收能量的效果極差，無法有效刻劃出圖形；依據固體雷射機台的聚焦原理得知，短聚焦透鏡較長聚焦透鏡的優點為能有效聚焦能量於基材、雷射焦點寬度較細和熱影響區域小等的特性都有助於刻劃出圖形，故更改機台原60 mm聚焦透鏡成40 mm聚焦透鏡。另一製程重點為使用雷射刻劃期間伴隨的高溫會產生黑色熔渣殘留於圖形旁邊，此黑色熔渣會影響覆晶型LED的出光亮度，且無法使用ACE、IPA等有機溶劑清洗，只能用高溫磷酸清洗熔渣，並使用厚二氧化矽保護磊晶層。
本研究使用半導體激發固體雷射器分別刻劃水平基板和圖形化基板，藍寶石面均為棋盤式圖形且有間隔50 μm、30 μm和對照組共六組圖形，30 μm間隔為機台作業時載台的步進馬達所移動之最小距離，50 μm間隔作為比較組，並於製程完成後主要比較光亮度差異；而根據量測結果，首先透過I-V曲線圖確認雷射刻劃技術在使用40 mm聚焦透鏡下刻劃覆晶型LED藍寶石表面並不會對元件的電性造成損壞；相較於未雷射刻劃之覆晶型紫外光LED元件，雷射刻劃加工過後水平基板的間隔30 μm、50 μm光輸出功率有顯著的28.7 %和16.7 %之提升；圖形化基板間隔30 μm、50 μm光輸出功率也有7.2 %和5.9 %之提升，此提升趨勢與使用Tracepro模擬軟體所得出之出光總量增加結果相符合。

In this paper, we use the diode pump solid state laser to scribe UV LEDs which can enhance the light extraction efficiency. The concept of laser scribing to enhance the brightness is derived from the pattern sapphire substrate surface. The micro-structure can improve the light extraction efficiency, so the purpose of this paper is using laser to scribe pyramid pattern which can enhance the light extraction efficiency. The relations between spacing of different checkerboard structure and light extraction efficiency also dicussed.
In order to fabricate micro-pyramid structures, the machine parameters is adjusted to a extreme condition of low energy (0.3 W) and high scribing speed (120 mm / s). But in this condition, the sapphire substrate is hard to absorb energy. According to paper, focus of the short focal lens has the advantage of focusing energy on the substrate.The high temperature will cause black slag residual at the edge of the patterns, and the black slag will affect the brightness of the flip-chip LED. Black slag can not be removed by ACE, IPA and other organic solvents, and can only be removed by phosphoric acid with high temperature. Before the process of cleaning slag, the thick SiO2 was deposited to protect the epitaxial layer.
We used the laser to scribe horizontal substrate and pattern substrate, and discuss three kinds of checkerboard spacing on these two substrates which are 50 μm, 30 μm and reference. After the processes are completed, the brightness of different samples were investigated. According to I-V curve, laser scribing techonology on sapphire surface does not damage the UV LEDs electrical properties. After laser scribing horizontal substrate, light output power of spacing 30 μm, 50 μm increase 28.7% and 16.7%; pattern sapphire substrate of spacing 30 μm, 50 μm increase 7.2% and 5.9%, compared with reference.The result is similar with the Tracepro simulation software.

目錄
誌謝 i
摘要 ii
ABSTRACT iii
目錄 iv
表目錄 vii
圖目錄 viii、ix
第一章 緒論 1
1-1 前言 1
1-2 研究目的 2
1-2-1 紫外光LED發光效率不足之原因 2
1-2-2 提升紫外光LED發光效率之技術 3
1-3 研究動機與論文架構 4
第二章 半導體激發固體雷射機台原理與覆晶二極體簡介 5
2-1 雷射(LASER) 5
2-1-1 諧振放大(Resonance) 5
2-2 雷射種類介紹 7
2-2-1 半導體激發固體雷射（Diode Pump Solid State Laser） 7
2-2-2 雷射二極體的特性 8
2-2-3 雷射機台40 mm短聚焦透鏡(Focal lens) 8
2-3 覆晶技術 9
2-4 發光二極體光取出之機制 11
2-4-1 內部量子效率 (Internal Quantum Efficiency) 11
2-4-2 光萃取效率 (Extraction Efficiency) 12
2-4-3 外部量子效率 (External quantum Efficiency) 12
2-5 光度計量與單位 15
第三章 實驗步驟 17
3-1 前言 17
3-2 雷射刻劃之覆晶結構(Flip-Chip)LED製作流程 17
3-2-1 近紫外光氮化鎵試片之磊晶結構 17
3-2-2 試片之清洗 17
3-2-3 乾式蝕刻至n-GaN製作 18
3-2-4 元件拋光製程 18
3-2-5 保護磊晶面之厚二氧化矽(SiO2)製作 19
3-2-6 固態半導體雷射切割圖形刻劃製作 19
3-2-7 金屬反射鏡面(Mirror)製作與熱退火(Anneal)製程 19
3-2-8 保護電極氧化層與兩側大小電極製作 20
3-2-9 覆晶保護氧化層與覆晶金屬電極製作 21
3-2-10 元件劈裂 22
3-2-11 覆晶接合製程 22
3-3量測儀器介紹 23
3-3-1 光電量測系統 23
3-3-2 掃描式電子顯微鏡 23
3-3-3 積分球 24
3-4 Tracepro模擬軟體介紹 26
3-4-1 Tracepro軟體簡介 26
3-4-2 模擬參數設定方式 26
第四章 結果與討論 28
4-1 Tracepro模擬軟體參數設定與結果分析 28
4-2 反射鏡面與全反射逃脫角之探討 30
4-2-1 反射鏡面之歐姆接觸探討 30
4-2-2 全反射與臨界角之分析 31
4-3 元件特性分析 33
4-3-1 電流-電壓特性 33
4-3-2 覆晶型長波紫外光LED發光強度分析 36
4-3-3 覆晶型紫外光LED外部量子效率 38
4-3-4 覆晶型長波紫外光LED電流對波長影響之分析 40
4-3-5 覆晶型紫外光LED發光角分析 42
4-3-6 覆晶型紫外光LED之封裝點膠分析 45
第五章 結論 46
第六章 未來展望 47
參考文獻 48

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