利用陽極氧化鋁為蝕刻光罩研究

Abstract

本實驗主要分成兩部份，第一部分為對Sapphire/SiO2/Al結構進行電解，將表面的Al膜氧化為陽極氧化鋁(AAO)，配合不同二次陽極氧化條件以及擴孔時間，製作出具有不同孔洞深寬比(孔洞深度/孔洞直徑)的陽極氧化鋁薄膜。第二部份則是利用各種不同孔洞深寬比的陽極氧化鋁，將其作為蝕刻光罩(etching mask)，以ICP蝕刻將陽極氧化鋁上的奈米孔洞圖案轉移至SiO2上。初步實驗結果發現低壓條件(5mTorr)相較於高壓條件(50mTorr)有較好的圖案轉移效果，不過在低壓條件下對於AAO也有一定程度的蝕刻效果，換言之就是低壓條件下的選擇性較差，另外孔洞的深寬比也會影響圖案轉移成功與否，實驗結果低壓條件下AAO薄膜厚度380nm~700nm的範圍中，孔洞深寬比在7.5~12範圍內可以成功的轉移奈米圖案。最後則是在2吋晶圓的大面積上，成功的將AAO的圖案轉移至SiO2上。

There are two major part in this research. In part one, we use the sample with the structure of Sapphire/SiO2/Al as anode and apply with voltage. In this way, Al layer will be oxidized into anodic aluminum oxide(AAO). By using different two step anodization condition and pore widening time, we can get the AAO film with different pore aspect ratio(pore depth/pore diameter). In part two, we make use of these AAO film with different aspect ratio as etching masks. Then, we use ICP etching to transfer the nano-porous pattern from AAO to SiO2. From experimental result, we find The low pressure ICP condition (5mTorr) has better etching profile on SiO2 than the high pressure ICP condition (50mTorr). However, the low pressure condition do some damage to AAO etching mask. Besides, the pore aspect ratio of AAO affect the result of pattern transfer. In this research, we find that the aspect ratio within 7.5~12 range will lead to success of pattern transfer. Finally, we demonstrate fabrication of the same structure on 2 inch Sapphire wafer successfully.