• Title, Summary, Keyword: Annular illumination

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Modified Illumination with a Concentric Circular Grating at the Backside of a Photomask (마스크 뒷면에 동심원 격자를 사용한 변형조명 방법)

  • Oh, Yong-Ho;Go, Chun-Soo;Lim, Sungwoo;Lee, Jai-Cheol
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.3
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    • pp.212-215
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    • 2005
  • Modified illumination techniques have been used to enhance the resolution of the sub-wavelength lithography. But, since they shield the central part of incident light, the light efficiency is seriously degraded, which in turn reduces the throughput of a lithography process. In this research, we introduced an annular illumination structure that enhances the light efficiency with a concentric circular grating at the backside of a photomask. The efficiency of the structure was theoretically analyzed.

Off-Axis Illumination (패턴 분해능 및 초점심도 향상에 대한 사입사 조명)

  • 박정보;이성묵
    • Korean Journal of Optics and Photonics
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    • v.10 no.6
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    • pp.453-461
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    • 1999
  • In this paper, we have studied on the effects of annular and quadrupole illuminations by changing their conditions for enhancing the pattern resolution and depth of focus (OaF) in the optical lithography system using KrF Eximer laser 0.248$\mu$m and 0.65 NA. As a result, it is revealed that each illumination condition to optimize the resolution and the OaF for the mask containing the assistance pattern is different under the annular illumination. And in case of quadrupole illumination, we could ascertain that the resolution and the OaF would be enhanced through changing the arrangement of each pole from the conventional X type (45 degrees) to some proper type according to the main pattern direction. ction.

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Modified Illumination by Binary Phase Diffractive Patterns on the Backside of a Photomask (마스크 뒷면에 2 위상 회절 격자를 구현한 변형 조명 방법)

  • 이재철;오용호;고춘수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.7
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    • pp.697-700
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    • 2004
  • We propose a method that realizes the modified illumination by implementing a binary phase grating at the backside of a photomask. By modeling the relationship between the shape of a grating on the photomask and the light intensity at the pupil plane, we developed a program named MIDAS that finds the optimum grating pattern with a stochastic approach. After applying the program to several examples, we found that the program finds the grating pattern for the modified illumination that we want. By applying the grating at the backside of a photomask, the light efficiency of modified illumination may be improved.

Recent Trends of Lithographic Technology (반도체 공정용 리소그래피 기술의 최근 동향)

  • Chung, T.J.;You, J.J.
    • Electronics and Telecommunications Trends
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    • v.13 no.5
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    • pp.38-52
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    • 1998
  • Phase-shifting masks (PSM), optical proximity correction (OPC), off-axis illumination (OAI), annular illumination (AI)의 리소그래피 분해능 향상 기법과 deep ultraviolet photoresist의 개발 및 리소그래피의 최근 기술 동향을 요약 소개한다. DUV 리소그래피의 대안으로 관심을 끌고 있는 scattering with angular limitation projection electron-beam lithography (SCALPEL), extreme ultraviolet lithography (EUVL), X-ray lithography (XRL), ion projection lithography (IPL) 등의 새로운 리소그래피 기술들의 기본 원리와 최근 기술 동향도 소개하였다. 리소그래피는 반도체 공정에 있어서 가장 중요한 부분을 차지하기 때문에 리소그래피의 최근 기술 동향을 검토해 봄으로써 국내 리소그래피 장비 산업의 기술 개발을 위한 방향 설정에 도움이 될 것으로 생각한다.

Development of Annular Optics for the Inspection of Surface Defects on Screw Threads Using Ray Tracing Simulation (광선추적을 사용한 나사산 표면결함 검사용 환형 광학계 개발)

  • Lee, Jiwon;Lim, Yeong Eun;Park, Keun;Ra, Seung Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.6
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    • pp.491-497
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    • 2016
  • This study aims to develop a vision inspection system for screw threads. To inspect external defects in screw threads, the vision inspection system was developed using front light illumination from which bright images can be obtained. The front light system, however, requires multiple side images for inspection of the entire thread surface, which can be performed by omnidirectional optics. In this study, an omnidirectional optical system was designed to obtain annular images of screw threads using an image sensor and two reflection mirrors; one large concave mirror and one small convex mirror. Optical simulations using backward and forward ray tracing were performed to determine the dimensional parameters of the proposed optical system, so that an annular image of the screw threads could be obtained with high quality and resolution. Microscale surface defects on the screw threads could be successfully detected using the developed annular inspection system.

Calculation for the pattern degradation of the parabolic reflector caused by both the surface roughness of the reflector and the structural misalignment (반사판의 표면거칠기와 구조의 오정렬에 의한 파라볼라 반사판 안테나 패턴 일그러짐 계산)

  • 김주완;김병성;남상욱;이충웅
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.32A no.1
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    • pp.36-44
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    • 1995
  • For a parabolic reflector antenna, a simple method is presented for computing efficiently the average power pattern degradations caused by the surface roughness of the reflector and misalignments between the reflector and the feed. In this procedure, both nonuniform surface errors and nonuniform illuminations are employed. The assumptions to derive the expressions are that in each annular region of the antenna, the rms value of the surface roughness is known, and in a zone in a annular region, the phase error by misalignments is constant, and can be taken to its value at the center of the zone. Detailed parametric studies are performed with derived expressions to determine the effects of those errors and illumination tapers on parameters such as gain and sidelobe levels.

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Research on the optimization of off-axis illumination condition and sub-resolution pattern size for the $0.1{\mu}m$ rule dense pattern formation ($0.1{\mu}m$급 dense 패턴 형성을 위한 사입사 조명 조건과 OPC 보조 패턴 크기의 최적 조건에 관한 연구)

  • 박정보;이재봉;이성묵
    • Korean Journal of Optics and Photonics
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    • v.12 no.3
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    • pp.190-199
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    • 2001
  • In this paper, we have researched the depth of focus (DOF) and cutoff intensity of the $0.1{\mu}m$rule dense line'||'&'||'space pattern according to the various off-axis illumination (OAl) conditions in the optical system of 0.65 NA using ArF excimer laser (193 nm). We have also studied the variation of the DOF and cutoff intensity according to the sub-resolution pattern (hammer head type) size for optical proximity correction (OPC) applied to the capacitor pattern and the various OAl conditions in the same optical system. As a result, it is revealed that the cross type quadrupole or annular illumination is preferred to the conventional X type quadrupole for printing the $0.1{\mu}m$ rule dense pattern. Also, we can investigate the optimal illumination condition and the size of ope sub-resolution pattern to keep a consistent DGF and cutoff intensity trends.

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Heterogeneous Photocatalytic Decomposition of Organics in Water Phase ($TiO_2$ 광촉매를 활용한 수용액 내의 유기물질의 광분해반응)

  • Lee, Tai-K.;Kim, Dong-H.;Kim, Kyung-N.;Auh, P. Chung-Moo
    • Solar Energy
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    • v.15 no.2
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    • pp.65-75
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    • 1995
  • We have summarised some important aspects of our recent basic and applied studies in the area of photocatalytic detoxifcation with Degussa P25 titanium dioxide($TiO_2$) being the photocatalyst. Heterogeneousphotocatalytic decompositions of two components such as TCE-chloroform, TCE-phenol and TCE-benzene as well as single component organic, TCE, chloroform and $CCl_4$ were carried out to investigate the effect of additional compound on the TCE decomposition rate. In laboratory experiments, the optimum flow rate of TCE solution was $200cm^3/min$ with annular photoreactor in the presence of 0.1 wt% $TiO_2$ powder under illumination. It was observed that the second compound such as $CHCl_3$, phenol and benzene has a negative effect on the TCE decomposition rate. Result presented that TCE decomposition ratio was increased at low pH in the TCE-phenol two component solution. It could be shown that the photocatalytic reactor exhibits technical feasibility of detoxifying the multicomponent under proper experimental conditions.

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Treatment of Waste Air Containing Malodor and VOC: 2. Effect of Light-intensity on the Photocatalytic Removal Efficiency of Malodor and VOC of Waste Air (악취 및 VOC를 함유한 폐가스의 광촉매 처리: 2. 광도의 폐가스 처리효율에 대한 영향)

  • Lee, Eun Ju;Lim, Kwang-Hee
    • Korean Chemical Engineering Research
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    • v.50 no.6
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    • pp.952-959
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    • 2012
  • The photocatalytic reactor was designed to have improved efficiency by enhancing a light intensity of photocatalytic reactor using a reflector coated on the surface at the outer radius of annular shaped photocatalytic reactor. The improved photocatalytic reactor performed to treat waste air containing malodor and VOC with the enhanced light intensity, of which the effect on their removal efficiency was investigated. The intensities of illumination of the improved photocatalytic reactor filled with porous silica-based media and nonporous glass bead media carrying photocatalyst were observed to increase by 28.5% and 30.1%, respectively, compared to those of photocatalytic reactor without any reflector. Using the improved photocatalytic reactor filled with porous silica-based media and nonporous glass bead media carrying photocatalyst, the removal efficiencies were enhanced by 2~3% and insignificantly, respectively. The removal efficiencies of the optimized photocatalytic reactor with reflectors, filled with porous silica-based media carrying photocatalyst, were observed to increase by 26% and 60%, compared to those of photocatalytic reactor (i.e., 19% and 53%), without any reflector, filled with nonporous glass bead media carrying photocatalyst, for hydrogen sulfide and toluene, respectively. The roughness of used reflector surface was measured to be ca. four times as big as that of a commercial mirror. However, their removal efficiencies are expected to be enhanced by increasing an light intensity resulting from lowering the roughness of used reflector coated on the improved photocatalytic reactor in the future.