臺灣博碩士論文加值系統

隨著固態照明的演進，以發光二極體 (LEDs) 取代傳統照明的瓶頸主要在於提升亮度與有效的熱管理等方面。本論文以溼蝕刻得到的微織狀銦錫氧化物表面來增加光取出，取代感應耦合電漿 (ICP) 的表面粗化處理，將之應用在氮化鎵發光二極體得到光電特性的改善。
至於熱管理，一般對於氮化鎵發光二極體來說，雷射剝離技術是最常見改善散熱的製程，其後不論是以晶圓鍵合或是以電鍍方式製作金屬基板，其導熱率將遠優於藍寶石基板。
本論文亦探討垂直式氮化鎵發光二極體，並結合先前提到的微織狀銦錫氧化物以改善光電特性。在以KrF準分子雷射剝離氮化鎵發光二極體的藍寶石基板之前，以電鍍技術於藍寶石另一側沉積厚銅，最後成功製作出銅基板的垂直式氮化鎵發光二極體。目前得到的較佳製作方式，是在掛鍍電鍍銅進行之前，先用厚膜光阻遮擋切割走道，再進行電鍍銅製程，如此就可避開銅基板的切割問題。

With the development of solid-state lighting, the chief bottlenecks of replacing traditional lamps with light emitting diodes (LEDs) were enhancements in luminance and effective thermal management. In this paper, we increase light extraction efficiency with micro-textured indium tin oxide by wet etching, instead of surface-roughening treatment by ICP. Applying this technique to traditional GaN LEDs, we get improvements in optical and electrical characteristics.
As for thermal management, generally speaking, for GaN LEDs, laser lift-off technique is the most common process for improving heat dissipation, hereafter, no matter the fabrication of metal substrate is wafer bonding or electroplating, the thermal conductivity of metal will be much better than that of original sapphire substrate.
The vertical GaN LEDs will be discussed in this paper, combining with micro-textured indium tin oxide above mentioned to improve the optical and electrical properties of vertical GaN LEDs. Before lifting off sapphire substrates of GaN LEDs by KrF excimer laser, we employ the electroplating technique to deposit thick copper layer on the other side of sapphire substrate, and finally, the vertical GaN LEDs with copper substrates were fabricated successfully. To avoid dicing problems of copper substrates, separating each chip by defining thick photoresist on pitch between chips before rack copper electroplating is the better process in our experiments at present.

Abstract (In Chinese) ------------------------------------I
Abstract (In English) -----------------------------------II
Acknowledge (In Chinese) --------------------------------IV
Contents ------------------------------------------------VI
Table Captions ------------------------------------------IX
Figure Captions ------------------------------------------X

Chapter 1 Introduction -----------------------------------1
1-1 Development of Solid-State Lighting ------------1
1-1-1 History of Solid-State Lighting ----------1
1-1-2 Progress History of Light-Emitting Diodes - ------------------------------------------------2
1-2 Introduction to the Origin of Laser Lift-off
Technique --------------------------------------4
1-3 The Background of Electroplating Technique
Applied to LED Process -------------------------5
1-3-1 Wafer Bonding Process --------------------6
1-3-2 Electroplating ---------------------------7
Chapter 2 Principles and Process Techniques of Light-
Emitting Diodes -------------------------------12
2-1 Brief Introduction to the Principles of LEDs --12
2-2 An Overview of GaN LEDs -----------------------13
2-3 Electrical Properties of GaN LEDs -------------15
2-3-1 P-GaN Ohmic Contact ---------------------15
2-3-2 Indium Tin Oxide (ITO) and Current
Spreading Issue for Metal-Semiconductor
Contact Interface -----------------------16
2-4 Issue of Light Extraction Efficiency ---------18
2-5 Substrate Transferred from Sapphire to Metal --19
2-5-1 Laser Lift-off Process ------------------20
2-5-2 Copper Electroplating Technology --------21
2-5-2.1 Introduction --------------------22
2-5-2.2 Mechanism -----------------------23
2-5-2.3 Instruments of Copper
Electroplating ------------------24
Chapter 3 Process Flow of Lateral and Vertical Blue Light
GaN-based LEDs --------------------------------31
3-1 Fabrication of Conventional Lateral-Structure
GaN LEDs with Micro-Textured ITO Surface ------31
3-1-1 The Micro-Textured ITO Surface ----------31
3-1-2 Fabrication of the Conventional Structure
GaN LEDs --------------------------------32
3-2 Fabrication of P-side Down Laser Lift-off GaN
LEDs ------------------------------------------34
Chapter 4 Results and Discussions -----------------------41
4-1 Characteristics of the Micro-Textured ITO -----41
4-1-1 Electrical and Optical Characteristics of
conventional Micro-Textured ITO GaN LEDs -- -----------------------------------------43
4-1-2 Summary ---------------------------------44
4-2 Vertical-Structure Laser Lift-off GaN LEDs ----45
4-2-1 Electrical and Optical Characteristics of
Vertical-Structure Laser Lift-off GaN
LEDs ------------------------------------46
4-2-2 Summary ---------------------------------50
Chapter 5 Conclusions and Future Works ------------------69
5-1 Conclusions -----------------------------------69
5-2 Future works ----------------------------------71
Reference -----------------------------------------------75

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