224
Design and Analysis of a Laser Lift-Off System using an Excimer Laser
Bo Young Kim
1, Joon Ha Kim
1, Jin A Byeon
1, Jun Ho Lee
1† , Jong Hyun Seo
2, and Jong Moo Lee
31
Geometrical Optics Lab, Kongju National University, Kong-ju 314-701, Korea
2
Laser Total Solution co,. Ltd., Ojeon-dong, Uiwang 437-817, Korea
3
Electronics and Telecommunications Research Institute, Yuseong-gu, Daejeon 305-700, Korea
(Received July 31, 2013; Revised manuscript September 23, 2013; Accepted September 24, 2013)
Laser Lift-Off (LLO) is a process that removes a GaN or AIN thin layer from a sapphire wafer to manufacture vertical-type LEDs. It consists of a light source, an attenuator, a mask, a projection lens and a beam homogenizer. In this paper, we design an attenuator and a projection lens. We use the ‘ZEMAX’ optical design software for analysis of depth of focus and for a projection lens design which makes 7×7 mm
2beam size by projecting a beam on a wafer. Using the ‘LightTools’ lighting design software, we analyze the size and uniformity of the beam projected by the projection lens on the wafer. The performance analysis found that the size of the square-shaped beam is 6.97×6.96 mm
2, with 91.8 % uniformity and ±30 μm focus depth. In addition, this study performs dielectric coating using the ‘Essential Macleod’ to increase the transmittance of an attenuator. As a result, for 23 layers of thin films, the transmittance total has 10-96% at angle of incidence 45-60° in S-polarization.
Keywords: Projection lens, Depth of focus, Attenuator, Laser lift-off
OCIS codes: (220.0220) optical design and fabrication; (080.3620) lens system design
엑시머 레이저를 사용한 LLO 시스템 설계 및 분석
김보영
1ㆍ김준하
1ㆍ변진아
1ㆍ이준호
1† ㆍ서종현
2ㆍ이종무
31
국립 공주대학교 대학원 광공학과
우
314-701 충청남도 공주시 신관동 182
2
( 주)엘티에스 전략제품기술부
우437-817 경기도 의왕시 오전동 38-13
3
한국전자통신연구원
우