• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.192-197
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• 1993

반도체 기억소자의 급격한 발전추세에 대응하기 위해서는 노광(exposure) 장비의 증첩정밀도 (overlay accuracy)가 같이 개선되어야 한다. 본 연구에서는 64M ERAM 제조를 목적으로개발된 스텝 퍼(stepper) 시스템의 성능평가 항목 중에서 증첩정밀도에대한 측정방법 및 현재까지의 연구결과를 기술하였다. 제작된 웨이퍼 정렬계는 off-axis 및 TTL 광학계와 이들 정렬신호에 따라 움직이는 웨이 퍼 구동계로 구성되어 있다. off-axis 광학계는 화상처리와 회절의 두 가지 방식이 가능하도록 설계 제작되었으며, TTL 광학계는 dual beam interferometric method를 이용하였다. 본 실험의 결과는 웨이퍼 정렬계의 특성을 평가한 것으로서, 현재까지 off-axis 정렬 방법만으로 얻은 증첩정밀도는 0.26-0.29$\mu$m (m+3 $\sigma$ )이다. 따라서 여기에 이미 제작되어 있는 TLL 정렬광학계를 추가로 사용하면 0.1 $\mu$m 이하의 정밀도에 이를 것으로 예측된다.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.412-418
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• 2009

This study aims to develop a system that enables 20 to 25 wafers to be automatically aligned at the position of the corresponding serial number and facilitates the checkout of wafer processing by sensing them before and after semiconductor processing. It also suggests compensation algorithm and stepper motor control algorithm that carefully align notches. This study minimizes the rate of occurrence by adopting materials of which the surface has proper coefficient of friction when wafers are rotating and that do not rarely produce particles. This study completed the development of a slip resistance apparatus and carried out performance tests through mathematical verification. This system is expected to improve semiconductor yield due to anti-pollution technology in semiconductor processing and can be selectively applied to a large size wafer over 450mm in the future.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.3
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• pp.71-74
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• 2013

In this study, the effects of wafer warpage on the misalignment during wafer stacking process were investigated. The wafer with $45{\mu}m$ bow height warpage was purposely fabricated by depositing Cu thin film on a silicon wafer and the bonding misalignment after bonding was observed to range from $6{\mu}m$ to $15{\mu}m$. This misalignment could be explained by a combination of $5{\mu}m$ radial expansion and $10{\mu}m$ linear slip. The wafer warpage seemed to be responsible for the slip-induced misalignment instead of radial expansion misalignment.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.3
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• pp.14-20
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• 2011

This study aims at aligning multiple wafers to reduce wafer handling time in wafer processes. We designed a multilevel structure for a prealigner which can handle multiple wafer simultaneously in a system. The system consists of gripping parts, kinematic parts, vacuum chucks, pneumatic units, hall sensors and a DSP controller. Aligning procedure has two steps: mechanical gripping and notch finding. In the first step, a wafer is aligned in XY directions using 4-point mechanical contact. The rotational error can be found by detecting a signal in a notch using hall sensors. A dual prealigner was designed for 300mm wafers and constructed for a performance test. The accuracy was monitored by checking the movement of a notch in a machine vision. The result shows that the dual prealigner has enough performance as commercial products.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.12
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• pp.105-114
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• 2003

In this study, a dicing machine with vision system was built and an algorithm for automatic alignment was developed for dual camera system. The system had a macro and a micro inspection tool. The algorithm was formulated from geometric relations. When a wafer was put on the cutting stage within certain range, it was inspected by vision system and compared with a standard pattern. The difference between the patterns was analyzed and evaluated. Then, the stage was moved by x, y, $\theta$ axes to compensate these differences. The amount of compensation was calculated from the result of the vision inspection through the automatic alignment algorithm. The stage was moved to the compensated position and was inspected by vision for checking its result again. Accuracy and validity of the algorithm was discussed from these data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.410-413
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• 2009

Wafer pre-alignment is to find the center and the orientation of a wafer and to move the wafer to the desired position and orientation. In this paper, an area camera based pre-aligning method is presented that captures 8 wafer images regularly during 360 degrees rotation. From the images, wafer edge positions are extracted and used to estimate the wafer's center and orientation using least square circle fitting. These information are utilized for the proper alignment of the wafer.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.150-156
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• 1994

To meet the process requirement of semiconductor device manufacturing, it is necessary to improve the alignment accuracy in exposure equipments. We developed the excimer laser stepper and will describe the methodology for alignment measurement and experimental results. Our wafer alignment system consists of off-axis optics, TTL(Through The Lens) optics and high precision stage. Off-axis alignment utilizes the image processing and /or diffraction from thealign marks of off-centered chip area. On the other hand, TTL alignment can be used for the die-by-die alignment using dual beam interferometry. When only off-axis alignment was used, the experimental alignment error(lml+3 .sigma. ) was 0.26-0.29 .mu. m, and will be reduced down to 0.15 .mu. m by adding TTL alignment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.141-141
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• 2003

• Korean Journal of Optics and Photonics
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• v.4 no.1
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• pp.15-21
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• 1993

This paper describes the design and development of a KrF excimer laser stepper and discusses the detailed system parameters and characterization data obtained from the performance test. We have developed a deep UV step-and-repeat system, operating at 248 nm, by retrofitting a commercial modules such as KrF excimer laser, precision wafer stage and fused silica illumination and 5X projection optics of numerical aperture 0.42. What we have developed, to the basic structure, are wafer alignment optics, reticle alignment system, autofocusing/leveling mechanisms and environment chamber. Finally, all these subsystem were integrated under the control of microprocessor-based controllers and computer. The wafer alignment system comprises the OFF-AXIS and the TTL alignment. The OFF-AXIS alignment system was realized with two kinds of optics. One is the magnification system with the image processing technique and the other is He-Ne laser diffraction type system using the alignment grating on the wafer. 'The TTL alignment system employs a dual beam inteferometric method, which takes advantages of higher diffraction efficiency compared with other TTL type alignment systems. As the results, alignment accuracy for OFF-AXIS and TTL alignment system were obtained within 0.1 $\mu\textrm{m}$/ 3 $\sigma$ for the various substrate on the wafers. The wafer focusing and leveling system is modified version of the conventional systems using position sensitive detectors (PSD). This type of detection method showed focusing and leveling accuracies of about $\pm$ 0.1 $\mu\textrm{m}$ and $\pm$ 0.5 arcsec, respectively. From the CD measurement, we obtained 0.4 $\mu\textrm{m}$ resolution features over the full field with routine use, and 0.3 $\mu\textrm{m}$ resolution was attainable under more strict conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.514-514
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• 2007

1차원 구조를 갖는 나노 와이어들은 나노 소자를 구현하기 위한 building-block으로 많은 과학자들의 주목을 받고 있고 또한 연구되고 있다. 하지만 그것을 정확하게 위치시키고 일정한 간격으로 정렬시키기 위한 기술 개발은 아직도 해결해야 할 큰 과제로 남아 있다. 이 논문에서, 우리는 ahsing 기술과 표면 패터닝 기술을 이용하여 대면적의 실리콘웨이퍼 위에 DNA(deoxyribonucleic acid)를 기반으로 한 금 나노 와이어를 정확하게 위치시키고 일정한 간격으로 정렬시킬 수 있는 새로운 제어 기술을 제안한다. 먼저 우리는 포토 리소그래피 공정과 $O_2$ 플라즈마 ashing 기술을 이용하여 선폭을 100 nm로 감소 시켰다. 그리고 자기조립단분자막 (self-assembled monolayers; SAMs) 방법과 lift-off 공정을 반복함으로서 1-octadecyltrichlorosilane(OTS) 층과 aminopropylethoxysilane(APS) 층을 형성하였다. 마지막으로 DNA 용액을 샘플 표면 위에 도포하고 분자 빗질 방법으로 DNA를 한 방향으로 정렬 시켰고 금 나노입자 용액을 처리하였다. 그 결과 금 나노 와이어는 $10{\mu}m$ 간격으로 일정하게 정열 되었고, APS 층에만 정확하게 정렬되었다. 우리는 금 나노 와이어를 관찰하기 위하여 원자간력 현미경 (Atomic Force Microscope AFM)을 사용하였다.