Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Absolute Test for a 4-inch Flat and Its Measurement Uncertainty

4인치 평면의 절대 측정 및 측정불확도 계산

  • Kim, Su-Young (Department of Science of Measurement, University of Science and Technology) ;
  • Song, Jae-Bong (Korea Research Institute of Standards and Science) ;
  • Yang, Ho-Soon (Department of Science of Measurement, University of Science and Technology) ;
  • Rhee, Hyug-Gyo (Department of Science of Measurement, University of Science and Technology)
  • 김수영 (과학기술연합대학원대학교 측정과학과) ;
  • 송재봉 (한국표준과학연구원) ;
  • 양호순 (과학기술연합대학원대학교 측정과학과) ;
  • 이혁교 (과학기술연합대학원대학교 측정과학과)
  • Received : 2017.09.26
  • Accepted : 2017.11.09
  • Published : 2017.12.25
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Abstract

The flatness of a reference flat plays an important role, from the calibration of an interferometer to the reference for a semiconductor or flat-panel display, etc. Especially if we order the flatness measurement outside Korea, we may spend more time and money. In this paper, we measured the flatness of a reference flat using a three-flat test, which is one of the absolute measurement methods, and calculated its measurement uncertainty. In the three-flat test we adopted, each flat is tested against another flat, with three unknown flats, using an interferometer. Among several three-flat tests, we adopted Griesmann's method which has a low measurement uncertainty and is less dependent on the experimental equipment. As a result, the measurement uncertainty was found to be less than 0.5 nm rms, which is very accurate for high-tech industrial applications.

기준 평면의 평면도는 간섭계 교정에서부터 반도체, 플랫 패널 디스플레이, 실리콘 기판에 필요한 기준면 제공 등에 매우 중요한 역할을 한다. 특히 기준 평면의 평면도 측정을 해외에서 수행해 올 경우 시간적인 지연과 함께 금전적인 손해가 크므로 국내에서 측정 기술을 구축할 필요가 있다. 본 논문에서는 국내에서 처음으로 절대 측정 방법인 three-flat test 방법을 사용해 기준 평면의 평면도를 정확하게 구하고 측정불확도를 계산하였다. Three-flat test는 간섭계를 사용하여 세 개의 기준 평면을 상호 비교 측정하여 얻은 결과에서 각 평면의 평면도를 정확하게 구하는 방법이다. Three-flat test 방법들 중 실험실에 구축된 장비로 실험 가능하며 간단한 계산 과정으로 낮은 측정불확도를 얻을 수 있는 Griesmann 방법을 적용하여 실험하였다. 그 결과, 세 광학 평면에 대한 평면도를 얻을 수 있었고, 측정불확도는 각 광학 평면에 대해 0.5 nm rms 이내의 신뢰 수준임을 확인하여 높은 수준으로 자체 평면도 측정이 가능함을 확인하였다.

Keywords

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