微結構於可撓式基材之製造

The Fabrication of Microstructures on Flexible Substrates

黃萌祺(Meng-Chi Huang)

指導教授 ： 傅建中

國立清華大學/工學院/奈米工程與微系統研究所/博士(2013年)

https://doi.org/10.6843/NTHU.2013.00107

摘要

可撓式基材具有輕、薄、可撓曲，且不受場合、空間限制的優點，因此經常被應用於輕薄或可動式機構設計的產品，如：無線智慧標籤（RFID）、可撓式電子書報、超薄平面顯示器等。其中以塑膠基板最常被使用，其優點為透明、高安全性、並適合Roll-to-Roll的高生產效率。但現今塑膠基板的模具製造或產品加工，仍存在許多問題，故本論文將針對這些問題提出解決方案，探討如下：
研究一：在Roll-to-Roll製程中，滾筒模具大多由超精密加工進行車削，但許多特殊的圖案是無法藉由超精密加工製造。本研究藉由軟微影(soft -lithography)與電化學蝕刻方式，將平面微結構轉印至不鏽鋼滾筒模具上，並成功的製造出直徑1.5mm到38mm之滾筒模具，且滾筒上之圖形不受任何限制，亦可以用於人字型軸承製造。
研究二：抗反射膜片可被應用於許多消費性電子產業，如：平面顯示器、照相機和太陽能電池。傳統上，使用多層膜法來製造抗反射膜片，但其有製程不穩定、且效果不佳等缺點。許多研究使用蛾眼奈米結構取代多層膜法當作抗反射膜片，但都只將蛾眼奈米結構製作於Si或氮化鎵晶圓上，在塑膠膜片上卻著墨不深。本研究藉由乾蝕刻方式蝕刻出奈米針尖陣列，再將其進行電鑄製程，最後利用熱壓PMMA而獲得抗反射膜片。與無結構PMMA比較，在可見光範圍中，抗反射率可從4.25﹪降至0.5﹪，亦遠優於3M公司所出產的抗反射膜片(1.1﹪)。
研究三：隨著光學設計的日益嚴苛，光學膜片上之微結構也日益複雜，有許多微結構已經無法使用現行的黃光微影技術或超精密加工進行加工。故本研究以背面曝光法，藉由控制基板的種類與厚度，可製造出具有傾斜面之大面積3D微結構，且無需改變曝光設備；並可進一步製造出無需經熱處理(reflow)之微透鏡。
研究四：隨著軟性顯示器的興起，於大面積軟性基材上進行微結構製程隨之重要，但傳統的黃光微影製程不易使用於大面積軟性基材上，故本研究藉由局部電化學沉積法，可定義圖案於陰極板中，再使用無電鍍沉積法增加微結構之厚度，於軟性基材上製造出微結構。且一次的黃光微影製程，可製造出超過50片相同微結構之陰極板，大幅減少黃光微影之需求。使用相同之方法，亦可將平面微結構轉印至滾筒模具上，製造Roll-to-Roll製程中之滾筒模具。
藉由上述之研究，將可製作出不受任何圖形限制的滾筒模具，利用Roll-to-Roll製程可於軟性基材中製造大面積的微結構，以降低成本，並開發出符合經濟效益的消費性電子產品。此外，亦可製造高效率之奈米針尖抗反射膜片與大面積3D微結構光學元件，可應用於新世代可撓性平面顯示器產業。

關鍵字

可撓式基材 ； 抗反射膜片 ； 滾筒模具

並列摘要

Flexible substrates are light, thin, and not restricted to the environments or spaces, and hence, are commonly applied to mobile devices, such as, RFIDs, electronic books, and ultra-thin displays. In particular, plastic substrates are most commonly used, because they are transparent, reliable, and suitable for Roll-to-Roll processes. However, there still remain several issues by using plastic substrates. This research will propose solutions to address these problems.
Study 1：In Roll-to-Roll processes, roller molds are generally manufactured by ultra-precision machining, but this process is not able to produce many special patterns. This research applied both soft-lithography and electro-chemistry to reproduce two-dimensional patterns onto the stainless roller mold, and successfully fabricated a roller mold with diameter of 1.5mm – 38mm, and no restrictions on the patterns.
Study 2：Anti-reflection thin-film can be applied to several consumer electronic devices, such as flat panel displays, cameras, and solar cells. Traditionally, it is fabricated by multi-thin film techniques, but the process is unstable and produces low quality thin-film. Many researchers have used nanostructures on silicon or gallium nitride as an alternative, but nanostructures on the plastic thin-film were barely reported. This research applied dry-etching technique to produce nanoscale arrays, and treated by electroforming and hot-pressing PMMA to produce anti-reflection thin-film. By comparing with unstructured PMMA, its anti-reflection rate was reduced from 4.25% to 0.5%, which was better than products of 3M (1.1%).
Study 3：The micro-structures on the optical thin-film is becoming more complex than ever, and some structures were already not able to produce by current lithography or ultra-precision machining techniques. Therefore, this research applied the backside exposure technique to produce large-inclined area with three-dimensional micro-structures by controlling the thickness of the substrates. Furthermore, the fabrication processes did not require additional exposure equipment, and no further heat flow treatment was required.
Study 4：The micro-structures on the large-area flexible substrates have become increasingly important, but it is difficult to produce structures on large-area flexible substrates by using lithography. Therefore, this research applied electrochemical deposition technique to define patterns on the electrodes, followed by electroless deposition technique to increase thickness and eventually produced micro-structures on flexible substrates. In addition, it was able to produce 50 pieces of electrodes with the same micro-structures in one lithography process. With the same method, it was also able to produce two-dimensional patterns on the roller mold for Roll-to-Roll equipment.
In this thesis, it is able to produce any patterns on the roller mold, by using Roll-to-Roll process to produce large-area micro-structures on the flexible substrates. By reducing the cost, economical consumer electronic devices can be developed. Moreover, high-efficiency nanoscale anti-reflection thin-film and large-area 3D micro-structures optical components can be applied to flexible displays industry.

並列關鍵字

Flexible substrates ； Anti-reflection thin-film ； Roller mold

參考文獻

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