In the present study, an optical system is proposed for maskless lithography using a digital micromirror device (DMD). The system consists of an illumination optical system, a DMD, and a projection lens system. The illumination optical system, developed for 95% uniformity, is composed of fly's eye l...
In the present study, an optical system is proposed for maskless lithography using a digital micromirror device (DMD). The system consists of an illumination optical system, a DMD, and a projection lens system. The illumination optical system, developed for 95% uniformity, is composed of fly's eye lens plates, a 405 nm narrow band pass filter (NBPF), condensing lenses, a field lens and a 250W halogen lamp. The projection lens system, composed of 8 optical elements, is developed for 4 ${\mu}m$ resolution. The proposed system plays a role of an optical engine for PCB and/or FPD maskless lithography. Furthermore, many problems arising from the presence of masks in a conventional lithography system, such as expense and time in fabricating the masks, contamination by masks, disposal of masks, and the alignment of masks, may be solved by the proposed system. The proposed system is verified by lithography experiments which produce a line pattern with the resolution of 4 ${\mu}m$ line width.
In the present study, an optical system is proposed for maskless lithography using a digital micromirror device (DMD). The system consists of an illumination optical system, a DMD, and a projection lens system. The illumination optical system, developed for 95% uniformity, is composed of fly's eye lens plates, a 405 nm narrow band pass filter (NBPF), condensing lenses, a field lens and a 250W halogen lamp. The projection lens system, composed of 8 optical elements, is developed for 4 ${\mu}m$ resolution. The proposed system plays a role of an optical engine for PCB and/or FPD maskless lithography. Furthermore, many problems arising from the presence of masks in a conventional lithography system, such as expense and time in fabricating the masks, contamination by masks, disposal of masks, and the alignment of masks, may be solved by the proposed system. The proposed system is verified by lithography experiments which produce a line pattern with the resolution of 4 ${\mu}m$ line width.
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문제 정의
This study is focused on the development of a 4 µm resolution optical system for high resolution maskless lithography using the DMD for PCB fabrication.
가설 설정
2) All five kinds of the third-order aberrations should be zero.
3) The telecentricity in image space should be zero.
5) The distance from the first surface to the last surface of the projection lens should be less than 140 mm.
6) The working distance from the substrate should be at least 30 mm.
제안 방법
To make these illumination beams uniformly illuminate the DMD surface and to let all of them again enter into the effective aperture of projection lens, we let all of them pass through a beam homogenizer consisted of condensing lenses, two fly’s eye lens plates, and a field lens.
대상 데이터
In the design, we used a 250W halogen lamp supplied by USHIO Co. and we used a NBPF to utilize the line width of 405nm ±2 nm.
The proposed system consists of an illumination optical system, a DMD, and a projection lens system. The illumination optical system composed of fly’s eye lens plates, a 405 nm NBPF, condensing lenses, a field lens and a 250W halogen lamp is developed to achieve 95% uniformity.
이론/모형
The program producing the initial solutions uses the optimization method which uses the damping least square method [19], and its algorithm is shown in Fig. 5.
성능/효과
For the 7 element system, the initial solutions were obtained either when a lens was added to the front of the stop or the back of the stop. As a result, it was confirmed that the third-order aberration was all eliminated for the initial solution and the amount of the residual fifth-order spherical aberration was 0.02 mm or more. In case of the 7 element system mentioned above, It had the residual spherical aberration larger than 20 µm, so it was considered to be a low-profile system that could not give the resolution of below 4 µm, and it was true when we optimized it.
참고문헌 (20)
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