藍寶石基板之乾式蝕刻及其應用於氮化鎵發光二極體之研究

Dry etching of sapphire substrates and its application for GaN-based light-emitting diodes

施文忠(Wen-Chung Shih)

指導教授 ： 方昭訓

共同指導教授 ： 武東星

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2004年)

https://doi.org/10.6827/NFU.2004.00002

摘要

本論文探討使用感應耦合電漿系統蝕刻藍寶石基板及其應用於成長
氮化鎵發光二極體。首先於 (0001) 藍寶石基板上製作鎳金屬遮罩，在
感應耦合電漿蝕刻系統中，使用氯及三氯化硼混合比例 2︰3 的混合氣體，
配合上電極功率 1200W、下電極功率 350W、直流偏壓 -250V、工作壓
力 3 mTorr、製程氣體總統量 20 sccm 之條件下，可得到藍寶石與鎳之蝕
刻選擇比為 6，且藍寶石之蝕刻率可達 180 nm/min，我們以此條件蝕刻出
不同尺寸與深度的圖案，製作完成圖案化之藍寶石基板，隨後在圖案化
藍寶石基板上利用有機金屬化學氣相沉積系統成長氮化鎵發光二極體結
構。實驗結果顯示，隨著圖案化藍寶石基板上圖案尺寸深度不同，可以
發現氮化鎵薄膜之磊晶品質有明顯之變化；光學特性分析顯示，氮化鎵
薄膜之光激發光頻譜強度增強 50% 以上，此外，藉由電子顯微鏡觀察證
實，氮化鎵薄膜成長於圖案化藍寶石基板上會產生橫向磊晶的效果而造
成氮化鎵磊品質改善；發光特性變強除了部份導因於磊晶品質改善
外，基板上之圖案會使活性層所產生之光線發生散射的效果也是另一項
重要因素，這種光學效應也可經由光學模擬得到證實。

關鍵字

non

並列摘要

We have investigated the inductively coupled plasma etching of the
sapphire substrate and its application for GaN-based LEDs. First the Ni mask
upon the c-face (0001) sapphire substrate was deposited by E-beam
evaporation. The etching process was performed under a Cl2/BCl3 (8/12
sccm) gas mixture with a chamber pressure of 3 mTorr. An etch rate of 180
nm/min with a selectivity ratio (sapphire over Ni) of ~6 was achieved under
an ICP power of 1200W and a bottom RF power of 350W. The original and
patterned sapphire substrates were then used to grow the GaN/InGaN
light-emitting diodes (LEDs) by using a metalorganic chemical vapor
deposition. Under optimum conditions, the photoluminescence peak intensity
was found to enlarge about 50% in magnitude for the LED sample with a
patterned sapphire substrate (PSS) at room temperature. These could be
attributed to the reduction of threading dislocaion density near the lateral
epitaxial growth regions. Furthermore, the light scattering effect by the PSS
was also confirmed by the optical simulation result, which improving the light
extraction effciency of the GaN LED. It is concluded that the PSS with an
optimum design can enhance GaN-based LED performance via both the
structure and light scattering improvements.

並列關鍵字

non

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