本研究主題為紫外光 (UV) 固化之奈米壓印微影技術，主要設計不同曲面的軟性矽膠 (PDMS) 撓性模具為基礎，搭配使用高分子材料醛氟聚醚 (Perfluoropolyethers, PFPE) 的壓印模仁，並與以鳩尾環固定之平面PDMS模仁形成一複合模具進行壓印。此一PFPE高分子材料可輕易從傳統矽模仁中翻製出線寬100 nm以下的奈米結構，且收縮率低於0.1%，在壓印製程上具有快速且可常溫操作之優點。根據設計不同曲面之可撓式模具，不僅能以圓形軸對稱擴散的方式施壓，也能產生一壓力梯度驅動UV阻劑向外運動，此壓印方法透過結果證明不僅能在細部上可以有效的控制殘留層厚度之外，也能成功製作出具漸變高度的阻劑結構。
實驗中同時利用壓力感測器 (Pressure Sensing System) 量測在基板間以不同曲面模具在壓印時的實際接觸壓力分佈，再由大量的實驗結果與過程中各階段的壓力分佈，可了解在壓力梯度的驅趕下對光阻結構與流動性影響的重要性。本文成功在四吋矽基板上製作出線寬160 nm、週期300 nm、具有漸變高度之奈米級結構，證實PFPE為一良好的壓印模具材料與此一奈米壓印製程的可行性，未來將有機會可應用於光電產業中所需之漸變結構的背光模組。
此外，本研究延伸此奈米壓印技術，成功製作最小線寬20 μm之接近六吋之黑光阻嵌入式任意圖形軟性光罩，先搭配一平行紫外光源於兩吋曲面基板上完成任意微結構製作，再利用掀離製程完成金屬任意圖形製作，此一實驗證實軟性光罩能夠有效貼附於曲面基板上製作任意圖形，最後也充分實現本文所發展之奈米壓印技術於奈米尺寸結構製作與黑光阻任意圖形軟性光罩之可行性與應用的潛力。

This research focuses on ultraviolet (UV) curing nanoimprint soft lithography based on the design of flexible PDMS molds. Combining the polymer Perfluoropolyethers (PFPE) with a plane PDMS mold embedded in a dovetail ring, a composite mold for imprinting is prepared. The PFPE mold can be replicated from a silicon mother mold with a line-width less than 100 nm and a shrinkage rate less than 0.1%. Fast UV nano-imprinting at room temperature can be realized. By designing flexible molds with different curvature, it not only allows applying pressure in a circularly axisymmetric manner but also generates a pressure gradient to drive the UV-curable resist to flow outward. The proposed imprinting method can achieve not only controllable residual layer thickness but also gradually varying structural height.
In the experiment, a pressure sensor (Pressure Sensing System) was used to measure the actual contact pressure distribution using different curved molds between the substrates during imprinting. Based on a lot of experimental results, we can understand the influence of the designed surface profiles and the resulted pressure distribution on the imprinted nano-structures. This work successfully fabricated nano-structures with a linewidth of 160 nm, a period of 300 nm, and a gradual structure height on a 4” silicon substrate. It proves that PFPE is a good imprinting mold material as well as the feasibility of this nanoimprinting process. In the future, it can be applied to backlight modules with nano-structures having gradually varying structural height required in the optoelectronic industry.
In addition, this research extends this nano-imprint technology and successfully fabricated a 6” black-photoresist embedded soft mask with a minimum linewidth of 20 μm, which allows photolithography patterning on a curved surface. As an example, metallic patterns are successfully produced on a 2” and curved plano-convex lens substrate using the black-photoresist embedded soft mask and standard lift-off processes. It extends the application of photolithography from planar substrates to curved ones, and numerous applications can be expected.

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