圖案化藍寶石基板之濕式蝕刻

Abstract

近年來，以InGaN/GaN為主的發光二極體(light-emitting diode, LED)有很大的進展。由於LED具備高亮度、壽命長以及高的穩定性，許多LED的新應用包括交通號誌燈、液晶螢幕的背光源以及一些發光上的應用已經被開發出來了。然而，為了未來的照明上的應用，更加增進LED的外部量子效率是非常重要的。 在本篇論文中，我們成功的利用濕式蝕刻來製作圖案化藍寶石基板。我們使用硫酸：磷酸= 3：1當作蝕刻溶液。與乾式蝕刻比起來，濕式蝕刻具有製程簡易、蝕刻速率高、蝕刻表面平滑以及價格低廉等優點。只要選擇適當的條件，我們就可以得到很高的蝕刻速率並且得到平滑的平面，最高的蝕刻速率可以超過3μm/min。本論文也找到了蝕刻速率與蝕刻時間的關係。同時，我們使用了不同的蝕刻條件製造了蝕刻圖案的不同藍寶石基板。為了之後的側向磊晶在圖案化藍寶石基板，我們可以設計不同的遮罩圖案來蝕刻出我們想要的圖案化藍寶石基板。

For last few years, there have been lots of progresses on InGaN/GaN-based light-emitting diodes (LEDs). Many new applications based on these LEDs including traffic light, backlight of TFT-LCD and some lighting applications, have been developed owing to the merits of LEDs, such as high-brightness, long-lifetime and high stability. However, for future illumination applications, it is very important to further enhance the external quantum efficiency of LED. In this research, patterned sapphire substrates were fabricated with wet chemical etching technology. A 3H2SO4：1H3PO4 volume mixture was used as the etchant. Compared to the dry etching, wet etching had several merits, such as simpler process, higher etching rate, pit–free etching surface and lower cost. With proper treatment, very high etching rate with smooth and pit-free surface was obtained. The highest etching rate we measured was above 3μm/min. The relation between etching rates and temperatures is investigated in this work. At the same time, different geometrical patterned sapphire substrate is manufactured with different etching conditions. For further LEPS (Lateral Epitaxy on Patterned Substrate) technique, we can design the mask pattern to get patterned sapphire substrate we want.