DOI QR코드

DOI QR Code

Precise Measurement of Ultra Small Retardation of Rubbed Polyimide Alignment Layer Using an Improved Transmission Ellipsometer

개선된 투과형 타원계를 사용한 러빙된 Polyimide 배향막의 초미세 위상지연 정밀 측정

  • Lyum, Kyoung Hun (Department of Molecular Science and Technology, Ajou University) ;
  • Park, Sang Uk (Ellipso Technology Co., Ltd.) ;
  • Yang, Seong Mo (Department of Molecular Science and Technology, Ajou University) ;
  • Yoon, Hee Kyu (Department of Molecular Science and Technology, Ajou University) ;
  • Kim, Sang Youl (Department of Molecular Science and Technology, Ajou University)
  • 염경훈 (아주대학교 분자과학기술학과) ;
  • 박상욱 ((주)엘립소테크놀러지) ;
  • 양성모 (아주대학교 분자과학기술학과) ;
  • 윤희규 (아주대학교 분자과학기술학과) ;
  • 김상열 (아주대학교 분자과학기술학과)
  • Received : 2013.02.13
  • Accepted : 2013.03.28
  • Published : 2013.04.25

Abstract

The precision of retardation measurement has been improved upto $3{\sigma}$ <0.005 nm after improvements are made to the conventional transmission ellipsometer. Improvements are made such that, i) the polarizer module instead of the sample stage is rotated, ii) the light source is replaced, iii) the starting points of two rotating modules are accurately synchronized, and iv) the fine background retardation is compensated. Together with the newly introduced RVD (Retardation Vector Difference) method, the improved instrument is successfully applied to characterize the ultra small optical birefringence of the rubbed polyimide alignment layer, after the residual retardation due to glass substrate whose magnitude is about 1.0 nm is properly subtracted. It is verified that the net retardation of the alignment layer ranges from 0.05 nm to 0.15 nm.

시료를 회전시키는 기존의 시료회전형 타원계에서 시료를 고정시키고 편광자모듈을 회전시키는 모듈회전형 타원계로 구조를 변경하고 광원교체와 회전모듈 동기화, 배경 미세이방성 보정 등을 통해서 위상지연값 측정정밀도를 $3{\sigma}$ <0.005 nm 까지 향상시켰다. 개선된 모듈회전형 타원계를 사용하고 RVD(Retardation Vector Difference) 방법을 도입함으로써 1.0 nm 정도의 잔류이방성을 가지는 유리기층의 효과를 배제한 러빙된 Polyimide 배향막의 순수 배향효과만에 의한 초미세 광학이방성을 정밀하게 측정하는 방법을 제시하였다. 순수 러빙으로 인한 배향막의 위상지연값은 0.05 nm 에서 0.15 nm 정도의 크기를 가짐을 확인하였다.

Keywords

References

  1. C. Benecke, H. Seiberle, and M. Schadt, "Determination of director distribution in liquid crystal polymer-films by means of generalized anisotropic ellipsometry," Jpn. J. Appl. Phys. 39, 525-531 (2000). https://doi.org/10.1143/JJAP.39.525
  2. J. A. Ekhoff, M. J. Farrow, D. M. Walba, and K. L. Rowlen, "Molecular orientation of a model liquid crystal alignment layer," Talanta 60, 801-808 (2003). https://doi.org/10.1016/S0039-9140(03)00141-3
  3. J. W. Ryu, S. Y. Kim, and Y. K. Kim, "Determination of the optic axis distribution of a hybridly aligned discotic material for wide-view films," J. Korean Phys. Soc. 57, 233-239 (2010). https://doi.org/10.3938/jkps.57.233
  4. C. Yu, J. Bae, C. M. Keum, and S. D. Lee, "Optical anisotropy of aligned pentacene molecules on a rubbed polymer corresponding to the electrical anisotropy," Current Applied Physics 10, 64-67 (2010). https://doi.org/10.1016/j.cap.2009.04.013
  5. M. Yamahara, M. Nakamura, N. Koide, and T. Sasaki, "Influence of rubbing conditions of polyimide alignment layer on optical anisotropy of immobilized liquid crystal film," Liquid Crystals 34, 381-387 (2007). https://doi.org/10.1080/02678290601097334
  6. F. Yang, G. Zoriniants, L. Ruan, and J. R. Sambles, "Optical anisotropy and liquid-crystal alignment properties of rubbed polyimide layers," Liquid Crystals 34, 1433-1441 (2007). https://doi.org/10.1080/02678290701732970
  7. K. Ichimura, Y. Susuki, T. Seki, A. Hosoki, and K. Aoki, "Reversible change in alignment mode of nematic liquid crystals regulated photochemically by command surfaces modified with an azobenzene monolayer," Langmuir 4, 1214-1216 (1988). https://doi.org/10.1021/la00083a030
  8. K. Miyachi, N. Kimura, Y. Yamada, and S. Mizushima, "The UV2A technology for large size LCD-TV panels," in Proc. The 17th International Display Workshops (Fukuoka, Japan, Dec. 2010), LCT1-1.
  9. S.-H. Kang, K. Kim, J. Lee, B. Jeon, J. Yeom, and S.-R. Cho, "Method of forming alignment layer and fabrication method of liquid crystal display using the same," Patent KR-20120301983 (2012).
  10. S.-Y. Kim, "The study of photo-sensitive polyimide containing methoxy cinnamate derivatives on photoalignment of liquid crystal," M.S. Thesis, Hongik University, Seoul (2011).
  11. S. U. Park, S. Y. Kim, and K. H. Lyum, "Precise measurement of ultra small optical anisotropy and substrate effect to LCD alignment layer versus rubbing strength by using transmission ellipsometry," IMID 2011 Program, 51-3.
  12. http://www.ellipsotech.com/Ellipsometer_02.html.
  13. G. Fang, J. Maclennan, and N. Clark, "High extinction polarimeter for the precision measurement of the in-plane optical anisotropy of molecular monolayers," Langmuir 26, 11686-11689 (2010). https://doi.org/10.1021/la101117n
  14. H. R. Kim and S. Y. Kim, "Precise measurement of optical anisotropy of rubbed polyimide on patterned glass and its nanoscale variation," Korean J. Opt. Photon. (Hankook Kwanghak Hoeji) 20, 281-287 (2009). https://doi.org/10.3807/KJOP.2009.20.5.281
  15. J. W. Ryu and S. Y. Kim, "Analysis of effective optic axis and equivalent retardation of composite optically anisotropic film by using transmission ellipsometry," Korean J. Opt. Photon. (Hankook Kwanghak Hoeji) 20, 288-293 (2009). https://doi.org/10.3807/KJOP.2009.20.5.288

Cited by

  1. Ellipsometric Expressions of Multilayered Substrate Coated with a Uniaxially Anisotropic Alignment Layer vol.24, pp.5, 2013, https://doi.org/10.3807/KJOP.2013.24.5.271
  2. Ellipsometric Expressions for a Sample Coated with Uniaxially Anisotropic Layers vol.26, pp.5, 2015, https://doi.org/10.3807/KJOP.2015.26.5.275
  3. Study of Ultra-Small Optical Anisotropy Profile of Rubbed Polyimide Film by using Transmission Ellipsometry vol.18, pp.2, 2014, https://doi.org/10.3807/JOSK.2014.18.2.156