陽極氧化鋁與蝕刻微影結合自動化氣輔紫外光固化製作奈米結構及其應用

Anodic aluminum oxide and nanosphere lithography combined with automated gas-assisted UV curing to replicate nanostructures with applications

黃星維(Hsing-Wei Huang)

指導教授 ： 楊申語

國立臺灣大學/工學院/機械工程學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201901116

摘要

奈米結構於物體表面造成抗反射、自潔等效能，已應用於光學、生醫、檢測及生活中，有極大發展潛力。許多製作奈米結構方法之設備成本高、製程複雜、製作耗時。本研究利用陽極氧化鋁技術以及奈米球蝕刻微影製程做出奈米結構模具，並透過自動化氣體輔助紫外光固化技術達到快速、簡單、低成本翻製出高品質奈米結構。
本研究首先製作模具，分為兩個製程: 一是陽極氧化鋁，另一是奈米球微影蝕刻。使用磷酸或草酸當作電解液，藉不同電壓，進行二階段陽極氧化鋁製程可製作奈米孔洞陣列模具。藉調控電解液及電壓獲取不同孔洞間距之模具；調控電解時間，可控制奈米孔洞深度；調控溼蝕刻時間可控制奈米孔洞直徑。另一製程奈米球微影蝕刻，將600 nm二氧化矽奈米球旋轉塗佈於PC基材上，接著進行反應離子蝕刻，藉不同氣體種類、流量及蝕刻時間，進行二階段奈米球微影蝕刻，獲得不同深寬比之奈米柱狀陣列模具，藉電鑄獲得奈米孔洞鎳模具。
本研究設計製作氣輔壓印紫外光固化機台。壓印腔體分為上下兩部分，中間以PDMS薄膜分開，下腔體抽真空，上腔體功能為通入氣體，透過氣體等向施壓於塗佈UV膠之奈米孔洞模具上。紫外光燈源裝置於上腔體上方，使壓入奈米洞之UV膠固化成型。為使精準控制擠膠量，本研究使用馬達控制導螺桿推動針筒精準擠膠於模具上，並進一步設置自動化，使擠膠、壓印、照光、脫模自動進行。
本研究接著在此自動化氣輔壓印紫外光機台上製作奈米柱陣列，所製作奈米柱最大深寬比達4.68。量測奈米柱結構進行反射率、接觸角及拉曼量測，以驗證其抗反射、疏水性與拉曼增強效果。量測結果顯示反射率均低於1.5%，以奈米球微影蝕刻800秒之模具製作之奈米柱陣列結構具有最佳抗反射效果，其反射率甚至低於0.11%。接觸角量測結果顯示接觸角皆大於100^o；於表面增強拉曼散射(Surface enhance Raman scattering, SERS)量測中，其檢測靈敏度(Enhancement factor, EF)均達10^5以上，其中使用磷酸、電壓180 V 陽極氧化鋁模具製作之效果為最佳，可達1.38×10^6。本研究證實自動化氣體輔助UV固化製程具有低成本、簡易、快速方式製作奈米結構並應用的潛力。

關鍵字

陽極氧化鋁 ； 奈米球微影 ； 反應離子蝕刻 ； 紫外光固化 ； 氣體輔助 ； 表面增強拉曼散射

並列摘要

The components with nanostructures on surface have been used for optical and biomedical functions. There are many methods for fabricating nanostructures, but these methods require high cost, complicated process, and long cycle time. This study proposes to fabricate molds with nano-pores using anodized aluminum oxide (AAO) and nanosphere lithography. Automated, gas-assisted UV curing facility have been used to fabricate nano-column from the molds with nano-pores.
In this study, the molds with nano-pores were first made by two processes: one is anodized aluminum oxide, and the other is nanosphere lithography. The two-stage anodized aluminum process is carried out with phosphoric acid or oxalic acid as the electrolyte, and different voltage are used to obtain the anodized aluminum molds with different hole spacings. Through the electrolysis time, the depth of the nano-pores can be controlled；Through the wet etching time, the diameter of nano-pores can be adjusted. Another process for fabricating molds with nano-pores is nanosphere lithography. Uniformly coating the nanospheres on the PC substrate through spin coating, and etching with controlled gas ion、flowrate and time, two-stage nanosphere lithography etching is performed to obtain molds of nano-pores array with different aspect ratios.
The gas-assisted UV curing facility was designed and implemented. The gas is blown into the upper chamber, and exert pressure on the AAO mold coated with the UV-curable resin in the vacuumed lower chamber. The upper and lower chambers are separated by a PDMS film. The UV resin is protruded into the nano-pores by the gas pressure to form nanopillars. The UV light in the upper chamber is then lit to cure and solidify the UV resin. The charging of the UV resin, gas-assisted filling of nano-pores and curing are precisely automated.
The automated gas-assisted UV curing facility was used to fabricate nanopillars array sucecesfully. The maximum aspect ratio of the nano-column is 4.68. Finally, the measurements of reflectivity, contact angle and surface enhanced Raman scattering (SERS) of the nano-column structures are carried out to verify anti-relection, hydrophobicity and enhancement effects. The measurement results show that all the reflectances are less than 1.5%. The nano-structures can even reduce the reflectivity to even lower than 0.11%. The contact angle measurement results show that the contact angles are all greater than 〖100〗^o; In the SERS measurement, the Enhancement effects(EFs) are all above 〖10〗^5, with the best as high as 1.38×〖10〗^6. This study demonstrates the potential for automated gas-assisted UV curing processes to produce nanostructures for optical and biomedical applications with low cost, simple process and little time.

並列關鍵字

AAO ； Nanosphere lithography ； UV curing ； Gas assisted ； Raman scattering

參考文獻

[1] Q. Fang et al., “A bare-eye based one-step signal amplified semiquantitative immunochromatographic assay for the detection of imidacloprid in Chinese cabbage samples,” Anal. Chim. Acta, vol. 881, no. Supplement C, pp. 82–89, Jun. 2015.

[2] X. Yan, H. Li, W. Zheng, and X. Su, “Visual and Fluorescent Detection of Tyrosinase Activity by Using a Dual-Emission Ratiometric Fluorescence Probe,” Anal. Chem., vol. 87, no. 17, pp. 8904–8909, Sep. 2015.

[3] D. Li, D.-W. Li, J. S. Fossey, and Y.-T. Long, “Portable Surface-Enhanced Raman Scattering Sensor for Rapid Detection of Aniline and Phenol Derivatives by On-Site Electrostatic Preconcentration,” Anal. Chem., vol. 82, no. 22, pp. 9299–9305, Nov. 2010.

[4] S. Rodriguez-Mozaz, M. J. L. de Alda, and D. Barceló, “Biosensors as useful tools for environmental analysis and monitoring,” Anal. Bioanal. Chem., vol. 386, no. 4, pp. 1025–1041, Jun. 2006.

[5] K. Kneipp, H. Kneipp, I. Itzkan, R. R. Dasari, and M. S. Feld, “Ultrasensitive Chemical Analysis by Raman Spectroscopy,” Chem. Rev., vol. 99, no. 10, pp. 2957–2976, Oct. 1999.