由於採用濕蝕刻製程可獲得相當多的好處，近年來氮化鎵濕蝕刻技術的開發越來越受到矚目。首先，濕蝕刻過程不會造成表面缺陷因此可以改善元件特性，接下來，由於濕蝕刻可以簡化製程步驟和縮短所需的製程時間，所以有利於大量製造，若以成本減少的角度來考量，濕蝕刻顯然是一個比較好的選擇，所以國內外對於氮化鎵濕蝕刻製程開發陸續投入了大量資源。
本文重點放在將紫外光發光二極體(UV-LED)應用於光電化學濕蝕刻(PhotoElectroChemical etching, PEC)方法來進行n型氮化鎵濕蝕刻，其中蝕刻的溶液選擇使用PH=11.0至 14.0的氫氧化鉀(KOH)溶液，濕蝕刻的光罩採用鈦/金(Ti/Au 300/3000)和鈦/鋁/鎳/金(Ti/Al/Ni/Au 250/1250/450/550)合金，光源的部份嘗試使用兩種紫外光發光二極體，尖峰波長分別為373nm、365nm的二極體來做為提供濕蝕刻能量的光源。目前紫外光發光二極體都是使用氮化鎵材料所製作，雖然操作發光二極體不需要冷卻，實驗中我們透過電熱致冷器控溫將氮化鎵發光二極體因熱而產生的紅移縮小，讓發光二極體的尖峰波長固定以維持足夠的能量來進行蝕刻，最後使用日亞化學(Nichia)所生產的紫外光發光二極體(365nm)光源成功驗證在PH=14.0的氫氧化鉀溶液中可以蝕刻n型氮化鎵，蝕刻深度為1.4um。

Because wet etching poses many advantages over dry etching, development of GaN wet etching has drawn more and more attentions in recent years. First of all, wet etching avoids surface damages and thus improves both device characteristics and production yield. Second, wet etching reduces the number of processing steps, shortens the processing time and improves the overall throughput. In terms of cost reduction, wet etching obviously is a better choice. Therefore, laboratories worldwide have put enormous amount of efforts in the development of GaN wet etching process.
This thesis focused on applying UV-LEDs to n-type GaN PhotoElectroChemical (PEC) wet etching. In our experiment, KOH solutions with PH values lying between 11.0 and 14.0 are used as etchants. We also examined both Ti/Au 300/3000 and Ti/Al/Ni/Au 250/1250/450/550 contacts as wet etching masks. Two UV-LEDs, whose peak wavelengths are 373nm and 365nm, respectively, were used as the light sources of wet etching. The UV-LEDs were also made from GaN based materials. Although cooling is not required for UV-LED operation, we attached a ThermoElectric Cooler (TEC) to control the temperature and performed the etching under a constant wavelength. Finally, we have demonstrated that UV-LED made from Nichia with 365 nm peak wavelength can be used to etch the n-GaN and stop on top of the p-GaN in a PH=14.0 KOH solution and the etching depth is around 1.4μm.

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