臺灣博碩士論文加值系統

奈米壓印微影技術具有低成本高產量的優點，被認為具有潛力的下一代配向技術。過去利用奈米壓印配向技術製作週期性溝槽的方式並沒有辦法給予一定方向的預傾角而容易產生配向缺陷，本研究利用奈米壓印技術製作出週期性奈米楔形結構，企圖使用楔形結構的斜坡給予液晶分子在驅動電壓後能往同一個方向轉動。我們利用電子束微影製作週期為1 μm的週期性楔形結構，使用奈米壓印技術將圖案翻印到塗佈SU8光阻的ITO玻璃基板上。本論文中使用不同的PDMS(Poly(dimethylsiloxane))製程方法測試配向效果，最後採用monoglycidyl ether-terminated PDMS當做垂直配向層。本實驗探討週期性楔形結構在工作電壓下液晶分子重新排列的現象，藉由週期性矩形溝槽的液晶盒當做對照，論證週期性楔形結構能比週期性矩形溝槽能有更好的配向效果，避免配向缺陷產生。

In this study, we used the nanoimprint lithography (NIL) to fabricate the periodic nano-wedges groove for vertical alignment. The incline slope from nano-wedges can control LC raising-up direction on applied voltage. The periodic triangle structure was made on silicon wafer by Electron beam lithography, then we chose perfluoropolyether(PFPE) as a mold to replicate the periodic triangle structure on silicon master. A photoresist material of SU-8 used as an imprint material was coated on the ITO glass, and Poly(dimethylsiloxane) (PDMS) used as an vertical alignment layer by an external hydrophobic property. For the contrast, we also fabricated the periodic nano-rectangular groove with 1μm pitch to assemble VA LC cell by some processes. It demonstrated that the LC cell of periodic nano-wedges structure has better optical symmetry than the periodic nano-rectangular groove and prevent reverse-twist domains.

中文摘要 I
Abstract II
致謝 III
目錄 IV
圖目錄 VII
Chapter 1 緒論 1
1.1 前言 1
1.2 論文架構 2
Chapter 2 液晶的物理特性與相關知識 3
2.1 液晶簡介 3
2.1.1 液晶的歷史[1] 3
2.1.2 液晶的分類[1, 2] 3
2.2 液晶的物理特性 7
2.2.1 液晶分子排列的秩序參數(S) [3] 7
2.2.2 液晶的彈性連續體理論[1] 7
2.2.3 液晶的雙折射性質[1] 9
2.2.4 電場效應[1] 12
Chapter 3 液晶的配向理論 13
3.1 配向簡介 13
3.2 配向機制 13
3.2.1 液晶分子的定向處理[1] 13
3.2.2 配向的錯向線[5] 14
3.2.3 摩擦配向[5] 16
3.2.4 溝槽理論 18
3.3 非接觸式配向技術 19
3.3.1 斜向蒸鍍法[1] 19
3.3.2 光配向法[5] 19
3.3.3 表面圖案化 22
3.4 多域分割垂直配向液晶顯示器 25
Chapter 4 PDMS配向膜特性 29
4.1 PDMS 特性 29
4.2 PDMS製備與接觸角量測 30
4.2.1 PDMS製備 30
4.2.2 接觸角與表面能[24] 32
4.3 PDMS oligomers 34
4.3.1 利用微接觸印刷轉移PDMS oligomers[26-28] 34
4.3.2 PDMS oligomers的製程方法 35
4.4 液晶樣品盒的製程方法 35
4.4.1 基板清洗 35
4.4.2 液晶盒製備 36
4.5 結果與討論 37
Chapter 5 週期性奈米結構的垂直配向液晶顯示器 46
5.1 研究動機 46
5.2 奈米壓印技術 47
5.2.1 文獻回顧 47
5.2.2 機台介紹 48
5.2.3 實驗母膜與軟膜製備 48
5.2.4 熱壓式奈米壓印 50
5.3 光電量測方法與架構 56
5.3.1 光電量測系統 56
5.4 週期性矩形溝槽結構 57
5.4.1 製程方式 57
5.4.2 結果與討論 58
5.5 週期性楔形溝槽結構 64
5.5.1 製程方式 64
5.5.2 結果與討論 65
Chapter 6 實驗總結與未來展望 71
6.1 實驗總結 71
6.2 未來展望 72
參考文獻 73

1.劉. 譯. 松本正一 角田市良 合著, 液晶之基礎與應用 (1996).
2.E. Lueder, Liquid crystal displays : addressing schemes and electro-optical effects (2001).
3.Tsvetkov, Acta Physicochim. USSR 16, 132 (1942).
4.鄭. 紀國鐘, 液晶顯示器技術手冊 (2002).
5.M. H. Kohki Takatoh , Mitsuhiro Koden , Nobuyuki Itoh , Ray Hasegawa , Masanori Sakamoto, Alignment technologies and applications of liquid crystal devices (2005).
6.D. W. Berreman, Solid surface shape and the alignment of an adjacent nematic liquid crystal, Physical Review Letters 28, 1683 (1972).
7.D. W. Berreman, Alignment of liquid crystals by grooved surfaces, Molecular Crystals and Liquid Crystals 23, 215-231 (1973).
8.J. Fukuda, M. Yoneya, and H. Yokoyama, Surface-Groove-induced azimuthal anchoring of a nematic liquid crystal: Berreman's model reexamined, Physical Review Letters 8, 187803 (2007).
9.K. Ichimura, Photoalignment of Liquid-Crystal Systems, Chemical Reviews 100, 1847-1874 (2000).
10.W. Y. Chou, Z. Y. Ho, F. C. Tang, Y. S. Mai, T. Y. Wu, H. L. Cheng, C. R. Sheu, C. C. Liao, and K. H. Liu, Ion-beam-processed SiO2 film for homogeneous liquid crystal alignment, Japanese Journal of Applied Physics 44, 876-878 (2005).
11.J. B. Kim, J. R. Lim, J. S. Park, H. J. Ahn, M. J. Lee, S. J. Jo, M. Kim, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, The directional peeling effect of nanostructured rigiflex molds on liquid-crystal devices: Liquid-crystal alignment and optical properties, Advanced Functional Materials 18, 1340-1347 (2008).
12.T. C. Lin, S. C. Yu, P. S. Chen, K. Y. Chi, H. C. Pan, and C. Y. Chao, Fabrication of alignment layer free flexible liquid crystal cells using thermal nanoimprint lithography, Current Applied Physics 9, 610-612 (2009).
13.H. J. Kim, J. G. Lee, H. G. Kim, S.-W. Choi, and S. S. Kim, Liquid Crystal Device with Nanopatterned Indium-Zinc-Oxide Layer, Japanese Journal of Applied Physics 49, 024207 (2010).
14.C. Y. Chen, and Y. L. Lo, Feasibility study on twisted nematic liquid-crystal cell with two cross-embedded wire-grid polarizers as alignment and electrode for projection displays, Appl. Optics 48, 6558-6566 (2009).
15.Y. W. Lim, C. H. Kwak, and S. D. Lee, Anisotropic Nano-Imprinting Technique for Fabricating a Patterned Optical Film of a Liquid Crystalline Polymer, Journal of Nanoscience and Nanotechnology 8, 4775-4778 (2008).
16.Y. W. Lim, D. W. Kim, and S. D. Lee, Polymeric optical films as patterned retarders and alignment layers for transflective liquid crystal displays, Molecular Crystals and Liquid Crystals 489, 183-193 (2008).
17.J. S. Gwag, M. Oh-e, K.-R. Kim, S.-H. Cho, M. Yoneya, H. Yokoyama, H. Satou, and S. Itami, A functionally separated nanoimprinting material tailored for homeotropic liquid crystal alignment, Nanotechnology 19, 395301 (2008).
18.FUJITSU, High-Image-Quality MVA Premium Liquid Crystal Display, FIND 20, 12~17 (2002).
19.S. H. Lee, S. M. Kim, and S.-T. Wu, Emerging vertical-alignment liquid-crystal technology associated with surface modification using UV-curable monomer, Journal of the Society for Information Display 17, 551-559 (2009).
20.Y. N. Xia, and G. M. Whitesides, Soft lithography, Annual Review of Materials Science 28, 153-184 (1998).
21.L. T. Creagh, and A. R. Kmetz, Mechanism of surface alignment in nematic liquid crystals, Molecular Crystals and Liquid Crystals 24, 59-68 (1973).
22.J. B. Kim, C. J. Choi, J. S. Park, S. J. Jo, B. H. Hwang, M. K. Jo, D. Kang, S. J. Lee, Y. S. Kim, and H. K. Baik, Orientational transition of liquid crystal molecules by a photoinduced transformation process into a recovery-free silicon oxide layer, Advanced Materials 20, 3073-3078 (2008).
23.S. H. Kim, Y. Cui, M. J. Lee, S.-W. Nam, D. Oh, S. H. Kang, Y. S. Kim, and S. Park, Simple fabrication of hydrophilic nanochannels using the chemical bonding between activated ultrathin PDMS layer and cover glass by oxygen plasma, Lab on a Chip 11, 348-353 (2011).
24.P. Hubert, and Y. Galerne, Surface tensions and anchoring transitions of nematic liquid crystals on gradually oxidized substrates, Applied Physics Letters 71, 1050-1052 (1997).
25.D. K. Owens, and R. C. Wendt, Estimation of the Surface Free Energy of Polymers, Journal of Applied Polymer Science 13, 1741-1747 (1969).
26.J. A. Wigenius, M. Hamedi, and O. Inganas, Limits to nanopatterning of fluids on surfaces in soft lithography, Advanced Functional Materials 18, 2563-2571 (2008).
27.Y. Ding, S. Garland, M. Howland, A. Revzin, and T. Pan, Universal Nanopatternable Interfacial Bonding, Advanced Materials 23, 5551-5556 (2011).
28.J.-H. Kim, H.-S. Hwang, S.-W. Hahm, and D.-Y. Khang, Hydrophobically Recovered and Contact Printed Siloxane Oligomers for General-Purpose Surface Patterning, Langmuir 26, 13015-13019 (2010).
29.S. Y. Chou, P. R. Krauss, and P. J. Renstrom, Nanoimprint lithography, Journal of Vacuum Science ＆ Technology B 14, 4129-4133 (1996).
30.S. Y. Chou, P. R. Krauss, and P. J. Renstrom, Imprint lithography with 25-nanometer resolution, Science 272, 85-87 (1996).
31.C.-H. Lin, H.-H. Lin, W.-Y. Chen, and T.-C. Cheng, Direct imprinting on a polycarbonate substrate with a compressed air press for polarizer applications, Microelectronic Engineering 88, 2026-2029 (2011).
32.D.-R. Chiou, L.-J. Chen, and C.-D. Lee, Pretilt angle of liquid crystals and liquid-crystal alignment on microgrooved polyimide surfaces fabricated by soft embossing method, Langmuir 22, 9403-9408 (2006).
33.H. Hah, S.-J. Sung, M. Han, S. Lee, and J.-K. Park, Effect of the shape of imprinted alignment layer on the molecular orientation of liquid crystal, Materials Science and Engineering: C 27, 798-801 (2007).