Thin-GaN發光二極體電性改善之研究｜國立中央大學博碩士論文系統

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研究生：	許建祺 Chien-Chi Hsu
論文名稱：	Thin-GaN發光二極體電性改善之研究 The Improvement of Electrical Characteristic in Thin-GaN Light-Emitting Diodes
指導教授：	張正陽 Jenq-Yang Chang
口試委員:
學位類別：	碩士 Master
系所名稱：	理學院 - 光電科學與工程學系 Department of Optics and Photonics
畢業學年度：	96
語文別：	中文
論文頁數：	88
中文關鍵詞：	電性改善、雷射剝離、thin-GaN發光二極體
外文關鍵詞：	thin-GaN LEDs, improvement of electrical characteristics, laser lift-off
相關次數：	點閱：7 下載：0
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以氮化鎵為基礎之發光二極體(GaN-based LED)的晶粒製程技術主要分為傳統的打線(Wire-Bonding)封裝製程、覆晶(Flip-Chip)製程以及thin-GaN製程等技術，由於藍寶石(Sapphire)基板之高熱阻使得傳統打線、覆晶製程不適用於高功率操作之LED。本論文主要研究thin-GaN製程，以晶圓鍵合(Wafer Bonding)技術與雷射剝離(Laser Lift-Off)技術，將氮化鎵薄膜封裝於導熱效果較佳之矽(Si)基板上。
在製作thin-GaN LED中，發現鈍化層(Passivation)完整性與緻密性會對LED之逆偏漏電流(Reverse Leakage Current)造成影響，而電漿損害(Plasma Damage)以及高串聯電阻(Series Resistance)也會破壞LED之順向偏壓(Forward Voltage)。針對改善thin-GaN LED之逆偏漏電流，我們利用高緻密性之二氧化矽(SiO2)做為鈍化層，成功將thin-GaN LED在-5V逆向偏壓之漏電流降至-0.15?A；在改善thin-GaN LED之順向偏壓，製作Ni薄膜避免電漿損害，以及移除未摻雜氮化鎵(u-GaN Removal)薄膜降低串聯電阻，有效下降thin-GaN LED之順向偏壓。
在我們製作之thin-GaN LED中，順向偏壓最佳約為3.6V，相較於文獻有改善空間；而本研究使用晶圓鍵合與雷射剝離技術，對thin-GaN LED建立製程平台，並改善thin-GaN LED之電特性表現。

Chip process technology of GaN-based light-emitting diodes includes wire-bonding, flip-chip, thin-GaN, and so on. However, wire-bonding and flip-chip are inappropriate for high-power LED chips due to high thermal resistance of sapphire substrates. In this thesis, the GaN thin flim is packaged on a material with higher thermal conductivity, silicon substrates, by wafer bonding technology and laser lift-off.
In the fabrication process of thin-GaN LED, we discover that the coverage and the denseness of passivation effect the reverse leakage current of LED. Further, plasma damage and series resistance also degrade the forward voltage of LED. To improve the leakage current of thin-GaN LED, a highly dense passivation made of SiO2 is utilized; leakage current achieves -0.15uA at reverse voltage of -5V. Also, Ni thin film applied to avoid damage caused by plasma is in order to ameliorate the forward voltage of thin-GaN LED. Moreover, decrease of series resistance is achieved by u-GaN removal, which is to reduce the forward voltage of thin-GaN LED.
The best forward voltage of our fabricated thin-GaN LED is 3.6V approximately; nevertheless, it still need to be improved more compared to the reference. A platform of thin-GaN LED chip process is established for improving the electrical characteristics of thin-GaN LED is utilized by wafer bonding and laser lift-off.

摘 要 ........................................................................................................ i
Abstract ....................................................................................................... ii
誌 謝 ...................................................................................................... iii
目 錄 ...................................................................................................... iv
圖 目 錄 ..................................................................................................... vii
表 目 錄 ...................................................................................................... xi
第一章 序論 ............................................................................................... 1
1-1 前言 ............................................................................................... 1
1-2 研究動機 ....................................................................................... 5
第二章 Thin-GaN 發光二極體與文獻回顧 ............................................. 8
2-1 發光二極體原理 ........................................................................... 8
2-1-1 發光二極體光特性之原理簡介 ................................................... 8
2-1-2 發光二極體電特性之原理簡介 ................................................. 12
2-2 Thin-GaN 發光二極體之特性討論 ........................................... 17
2-2-1 基板材料之熱傳導特性 ............................................................. 18
2-2-2 電流分佈對發光二極體之影響 ................................................. 20
2-3 Thin-GaN 發光二極體實驗製作之原理 ................................... 23
2-3-1 雷射剝離技術之原理簡介 ......................................................... 23
2-3-2 傳輸線模型之原理簡介 ............................................................. 26
2-3-3 電制激發光譜之量測系統介紹 ................................................. 28
2-3-4 電流電壓特性曲線之量測系統介紹 ......................................... 28
2-4 Thin-GaN 發光二極體之電特性改善 ....................................... 31
2-4-1 影響thin-GaN 發光二極體電特性之討論 ............................... 31
2-4-2 金屬歐姆接觸對於thin-GaN 發光二極體之影響 ................... 32
第三章 Thin-GaN 發光二極體之製作流程 ........................................... 38
3-1 Thin-GaN 發光二極體之前段製程 ........................................... 38
3-1-1 氮化鎵試片結構 ......................................................................... 38
3-1-2 孤立晶粒之製作 ......................................................................... 40
3-1-3 鈍化層之製作 ............................................................................. 47
3-1-4 p 側電極金屬與鍵合金屬之製作 .............................................. 49
3-2 晶圓鍵合與雷射剝離製程 ......................................................... 54
3-2-1 晶圓鍵合技術 ............................................................................. 57
3-2-2 雷射剝離製程 ............................................................................. 57
3-3 Thin-GaN 發光二極體之後段製程 ........................................... 59
3-3-1 移除未摻雜氮化鎵薄膜 ............................................................. 61
3-3-2 n 側電極金屬之製作 .................................................................. 62
第四章 Thin-GaN 發光二極體之量測與結果討論 ............................... 68
4-1 Thin-GaN 發光二極體電性改善製程與量測之對照 ............... 68
4-2 Thin-GaN 發光二極體改善逆偏漏電流之分析討論 ............... 70
4-2-1 應用不同硬式遮蔽層之逆偏漏電流量測結果及討論 ............ 70
4-2-2 應用不同鈍化層之漏電流量測結果及討論 ............................. 72
4-3 Thin-GaN 發光二極體改善順向偏壓之分析討論 ................... 74
4-3-1 應用不同硬式遮蔽層之順向偏壓量測結果及討論 ................ 74
4-3-2 應用不同鈍化層之順向偏壓量測結果及討論......................... 77
4-3-3 移除未摻雜氮化鎵之順向偏壓量測結果及討論 .................... 79
第五章 結論與未來展望 ......................................................................... 83
參 考 文 獻 ..................................................................................................... 85

                                

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