한국광학회지 (Korean Journal of Optics and Photonics)

  • 제34권2호
  • /
  • Pages.53-60
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  • 2023
  • /
  • 1225-6285(pISSN)
  • /
  • 2287-321X(eISSN)
한국광학회 (Optical Society of Korea)
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이중 파장 심자외선 카타디옵트릭 NA 0.6 대물렌즈 광학 설계

Catadioptric NA 0.6 Objective Design in 193 nm with 266 nm Autofocus

  • 김도희 (공주대학교 광공학과) ;
  • 주석영 (공주대학교 광공학과) ;
  • 이준호 (공주대학교 광공학과) ;
  • 김학용 (한국표준과학연구원 첨단측정장비연구소 우주광학팀) ;
  • 양호순 (한국표준과학연구원 첨단측정장비연구소 우주광학팀)
  • Do Hee Kim (Department of Optical Engineering, Kongju National University) ;
  • Seok Young Ju (Department of Optical Engineering, Kongju National University) ;
  • Jun Ho Lee (Department of Optical Engineering, Kongju National University) ;
  • Hagyong Kihm (Advanced Instrumentation Institute, Korea Research Institute of Standards and Science) ;
  • Ho-Soon Yang (Advanced Instrumentation Institute, Korea Research Institute of Standards and Science)
  • 투고 : 2023.03.06
  • 심사 : 2023.03.21
  • 발행 : 2023.04.25
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초록

193 nm에서 반도체 전공정 검사 장치에 적용될 수 있는 반사 굴절 혼합 형식(카타디옵트릭)의 수치 구경(numerical aperture, NA) 0.6 대물렌즈를 설계하였다. 200 nm 공간 분해능 및 0.15 mm 이상의 시야를 확보하기 위하여, 먼저 렌즈 전체 배치를 포커싱 렌즈 그룹, 필드 렌즈 그룹 및 NA 변환 그룹으로 구성하였으며, 선행 그룹에 포커싱된 빔의 수치 구경 값을 필요 값, 즉 0.6으로 변환하는 기능을 수행한다. 총 11매의 광학 소자로 구성된 최종 설계는 모든 관측 시야에 대하여 λ/80 이하의 RMS 파면 수차를 만족하였다. 또한 고분해능 대물렌즈의 높은 환경 민감도로 인한 온도 변화에 따른 광학계 성능 해석 결과, ±0.1 ℃의 온도 변화에서도 목표 성능 이하로의 성능 저하가 확인되어 온도 변화에 따른 광학 보상이 반드시 필요하였다. 이에 초점면 이동을 보상자로 적용할 경우, 20 ± 1.2 ℃까지 RMS 파면 수차 변화량이 λ/30 이하로 목표 성능을 만족하여 실제 반도체 공정 환경에서도 이용이 가능함을 확인하였다.

We designed a catadioptric objective lens with a 0.6 numerical aperture (NA) for semiconductor inspection at 193 nm. The objective lens meets major requirements such as a spatial resolution of 200 nm and a field of view (FOV) of 0.15 mm or more. We selected a wavelength of 266 nm for autofocus based on the availability of the light source. First, we built the objective lenses of three lens groups: a focusing lens group, a field-lens group, and an NA conversion group. In particular, the NA conversion group is a group of catadioptric lenses that convert the numerical aperture of the beam focused by the prior groups to the required value, i.e., 0.6. The last design comprises 11 optical elements with root-mean-squared (RMS) wavefront aberrations less than λ/80 over the entire field of view. We also achieved the athermalization of the objective lens with focus-shift alone satisfying the performance of RMS wavefront aberration below λ/30 at a temperature range of 20 ± 1.2 ℃.

키워드

과제정보

이 논문은 과학기술정보통신부 재원으로 한국연구재단-나노·소재기술개발사업(2021M3H4A3A01055840, "초정밀 고분해능 자외선 광학결정 렌즈 원천기술 개발") 및 산업통상자원부 재원으로 한국산업기술평가관리원(No. 1415177869, "patterned wafer의 초미세 불량 분석 검출 장비 개발")의 지원을 받아 수행된 연구임.

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