Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Design and Analysis of a Receiver-Transmitter Optical System for a Displacement-Measuring Laser Interferometer

위치변위 레이저 간섭계용 송수신 광학계의 설계 및 분석

  • Yun, Seok-Jae (Department of Computer, Communications, and Unmanned Technology, Hannam University) ;
  • Rim, Cheon-Seog (Department of Computer, Communications, and Unmanned Technology, Hannam University)
  • 윤석재 (한남대학교 컴퓨터통신무인기술학과) ;
  • 임천석 (한남대학교 컴퓨터통신무인기술학과)
  • Received : 2017.02.06
  • Accepted : 2017.02.27
  • Published : 2017.04.25
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Abstract

We present a new type of receiver-transmitter optical system that can be adapted to the sensor head of a displacement-measuring interferometer. The interferometer is utilized to control positioning error and repetition accuracy of a wafer, down to the order of 1 nm, in a semiconductor manufacturing process. Currently, according to the tendency of scale-up of wafers, an interferometer is demanded to measure a wider range of displacement. To solve this technical problem, we suggest a new type of receiver-transmitter optical system consisting of a GRIN lens-Collimating lens-Afocal lens system, compared to conventional receiver-transmitter using a single collimating lens. By adapting this new technological optical structure, we can improve coupling efficiency up to about 100 times that of a single conventional collimating lens.

초정밀도를 요구하는 반도체 소자 공정에서 웨이퍼의 위치와 반복정밀도를 파장의 수백분의 일로 오차가 거의 없는 상태에서 제어하기 위해 위치변위 레이저 간섭계가 필요하다. 특히 제조공정에서는 생산단가의 인하압박으로 인해 웨이퍼의 대형화가 시도되고 있고 이에 따라 넓은 변위량을 측정하면서 나노미터 급의 위치 정밀도를 지닌 레이저 간섭계가 더욱 절실하게 요구된다. 이런 기술적인 문제를 해결하기 위해서 간섭계에 사용되는 송수신 광학계에도 특별한 광학적인 고안이 필요하게 된다. 본 논문에서는, 송수신 광학부로서 단순하게 콜리메이팅 렌즈만을 사용하는 기존의 방식 대신에, GRIN 렌즈-콜리메이팅 렌즈-무초점 광학계로 구성되는 새로운 형식의 조금 복잡한 형태의 광학구조를 제안하였고 이를 통해 반사된 후 되돌아와 간섭계로 결합되는 광신호의 효율을 약 100배 정도 높일 수 있었다.

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References

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