Current Optics and Photonics

  • 제1권5호
  • /
  • Pages.505-513
  • /
  • 2017
  • /
  • 2508-7266(pISSN)
  • /
  • 2508-7274(eISSN)
한국광학회 (Optical Society of Korea)
권호 표지
DOI QR코드

DOI QR Code

Thickness Measurement of a Transparent Thin Film Using Phase Change in White-Light Phase-Shift Interferometry

  • Kim, Jaeho (School of Mechanical and Aerospace Engineering, Seoul National University) ;
  • Kim, Kwangrak (SNU Precision Co., Ltd.) ;
  • Pahk, Heui Jae (School of Mechanical and Aerospace Engineering, Seoul National University)
  • 투고 : 2017.05.18
  • 심사 : 2017.08.30
  • 발행 : 2017.10.25
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

Measuring the thickness of thin films is strongly required in the display industry. In recent years, as the size of a pattern has become smaller, the substrate has become larger. Consequently, measuring the thickness of the thin film over a wide area with low spatial sampling size has become a key technique of manufacturing-yield management. Interferometry is a well-known metrology technique that offers low spatial sampling size and the ability to measure a wide area; however, there are some limitations in measuring the thickness of the thin film. This paper proposes a method to calculate the thickness of the thin film in the following two steps: first, pre-estimation of the thickness with the phase at the peak position of the interferogram at the bottom surface of the thin film, using white-light phase-shift interferometry; second, accurate correction of the measurement by fitting the interferogram with the theoretical pattern through the estimated thickness. Feasibility and accuracy of the method has been verified by comparing measured values of photoresist pattern samples, manufactured with the halftone display process, to those measured by AFM. As a result, an area of $880{\times}640$ pixels could be measured in 3 seconds, with a measurement error of less than 12%.

키워드

참고문헌

  1. P. A. Flourney, R. W. McClure, and G. Wyntjes, "White-light interferometric thickness gauge," Appl. Opt. 11, 1907-1915 (1972). https://doi.org/10.1364/AO.11.001907
  2. H. Maruyama, S. Inoue, T. Mitsuyama, M. Ohmi, and M. Haruna, "Low-coherence interferometer system for the simultaneous measurement of refractive index and thickness," Appl. Opt. 41, 1315-1322 (2002). https://doi.org/10.1364/AO.41.001315
  3. P. Hlubina, D. Ciprian, J. Lunacek, and M. Lesnak, "Dispersive white-light spectral interferometry with absolute phase retrieval to measure thin film," Opt. Express 14, 7678-7685 (2006). https://doi.org/10.1364/OE.14.007678
  4. S. K. Debnath, M. P. Kothiyal, J. Schmit, and P. Hariharan, "Spectrally resolved white- light phase-shifting interference microscopy for thickness profile measurement of transparent thin-film layers on patterned substrates," Opt. Express 14, 4662-4667 (2006). https://doi.org/10.1364/OE.14.004662
  5. P. Hlubina, J. Lunacek, and D. Ciprian, "White-light spectral interferometric technique to measure a nonlinear phase function of a thin-film structure," Opt. Commun. 283, 4877-4881 (2010). https://doi.org/10.1016/j.optcom.2010.07.038
  6. Y. S. Ghim and S. W. Kim, "Spectrally resolved white-light interferometry for 3D inspection of a thin-film layer structure," Appl. Opt. 41, 799-803 (2009).
  7. S. W. Kim and G. H. Kim, "Thickness-profile measurement of transparent thin-film layers by white-light scanning interferometry," Appl. Opt. 38, 5968-5973 (1999). https://doi.org/10.1364/AO.38.005968
  8. Y. M. Hwang, S. W. Yoon, J. H. Kim, S. Kim, and H. Pahk "Thin-film thickness profile measurement using wavelet transform in wavelength-scanning interferometry," Opt. Lasers Eng. 46, 179-184 (2008). https://doi.org/10.1016/j.optlaseng.2007.07.005
  9. D. Mansfield, "The distorted helix: thin film extraction from scanning white light interferometry," Proc. SPIE 6186, 61860O (2006).
  10. D. Mansfield, "Extraction of film interface surfaces from scanning white light interferometry," Proc. SPIE 7101, 797978 (2008).
  11. B. Maniscalco, P. M. Kaminski, and J. Walls, "Thin film thickness measurements using scanning white light interferometry," Thin Solid Films 550, 10-16 (2014). https://doi.org/10.1016/j.tsf.2013.10.005
  12. D. S. Kim and S. H. Kim, "Fast thickness profile measurement using a peak detection method based on an acousto-optic tunable filter," Meas. Sci. Technol. 13, L1-L5 (2002). https://doi.org/10.1088/0957-0233/13/7/101
  13. J. W. You, S. Kim, and D. Kim, "High speed volumetric thickness profile measurement based on full-field wavelength scanning interferometer," Opt. Express 16, 21022-21031 (2008). https://doi.org/10.1364/OE.16.021022
  14. T. Jo, K. Kim, S. R. Kim, and H. J. Pahk, "Thickness and surface measurement of transparent thin-film layers using white light scanning interferometry combined with reflectometry," J. Opt. Soc. Korea 18, 236-243 (2014). https://doi.org/10.3807/JOSK.2014.18.3.236
  15. H. G. Tompkins and W. A. McGahan, Spectroscopic ellipsometry and reflectometry: a user's guide, (John Wiley & Sons INC, New York, 1999), pp. 8-21.
  16. K. G. Larkin, "Efficient nonlinear algorithm for envelope detection in white light interferometry," J. Opt. Soc. Am. A. 13, 832-843 (1996). https://doi.org/10.1364/JOSAA.13.000832
  17. P. de Groot and L. Deck, "Three-dimensional imaging by sub Nyquist sampling of white -light interferograms," Opt. Lett. 18, 1462-1464 (1993). https://doi.org/10.1364/OL.18.001462
  18. J. Schwider, R. Burow, K.-E. Elssner, J. Grzanna, R. Spolaczyk, and K. Merkel, "Digital wave-front measuring interferometry: some systematic error sources," Appl. Opt. 22, 3421-3432 (1983). https://doi.org/10.1364/AO.22.003421
  19. K. Itoh, "Analysis of the phase unwrapping problem," Appl. Opt. 21, 2470-2470 (1982). https://doi.org/10.1364/AO.21.002470
  20. S. R. Kim, J. H. Kim, and H. J. Pahk, "Fringe-order determination method in white-light phase-shifting interferometry for the compensation of the phase delay and the suppression of excessive phase unwrapping," J. Opt. Soc. Korea 17, 415-422 (2013). https://doi.org/10.3807/JOSK.2013.17.5.415