以ITO/Al作為反射層研製覆晶發光二極體

The fabrication of flip-chip light emitting diodes using ITO/Al as a reflective layer

陳彥勻(Yen-Yun Chen)

指導教授 ： 蘇水祥

共同指導教授 ： 洪立維(Li-Wei Hong)

義守大學/電機資訊學院/電子工程學系/碩士(2017年)

摘要

本論文旨在以ITO/Al作為反射層研製覆晶發光二極體（Flip Chip LED）並探討元件光電特性。覆晶技術（Flip Chip）又稱倒晶封裝，是晶片封裝技術的一種，常規製程中，覆晶LED使用Ag作為反射層（Reflective Layer），但Ag容易因為承受過多的電流或熱而產生銀遷移（silver migration）現象，造成元件金屬結構的破壞，進而使元件有漏電流、亮度降低與可靠度不佳的現象。
本論文製作兩種具不同反射層結構的覆晶發光二極體，反射層結構分別為ITO/Al和ITO/DBR/Al，其中DBR代表分佈式布拉格反射鏡。實驗結果顯示以ITO/Al做反射層之元件，電特性相對較佳，但亮度很低，主要原因在Al之反射率低於Ag；而以ITO/DBR/Al做反射層之元件光電特性與對照組相近，Vf為2.85 V，比對照組高1.4%，亮度達到96.45 lm，僅比對照組低0.9%；在可靠度方面，元件在點亮後72小時亮度僅下降1.18%，顯示藉由ITO/DBR/Al反射層結構有效解決Ag於製程中對元件特性之不良影響。

關鍵字

覆晶技術 ； 發光二極體 ； 反射層

並列摘要

The purpose of this thesis is to fabricate flip chip light-emitting diodes (LEDs) with ITO/Al as a reflective layer and discuss the photoelectric characteristics of components. Flip chip is one of the chip packaging technology. In the conventional process, the flip chip uses Ag as the reflective layer. But the Ag in the reflective layer is easily damaged by the phenomenon of silver migration due to excessive current or heat. And thus make the components have leakage current, brightness reduction and poor reliability.
In this study, two kinds of flip chip LED elements with various mirror structures are fabricated, ITO/Al and ITO/DBR/Al. Where DBR represents a distributed Bragg reflector. Experimental results show that LED with the ITO/Al reflective layer has a better electrical characteristic, but the brightness is very low. It results from the lower reflectivity of Al than Ag. The photoelectric properties of LED with an ITO/DBR/Al reflective layer were similar to those of the control device. Vf was 2.85 V, which was 1.4% higher than the control device. Luminance was 96.45 lm, which was 0.9% lower than the control device. With ITO/DBR/Al to be a reflective layer in the flip chip LED effectively solve the adverse effects resulted from a reflective layer of Ag.

並列關鍵字

Flip Chip Technology ； Light Emitting Diodes ； Reflective Layer

參考文獻

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