• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.824-827
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• 2002

12inch 이상의 웨이퍼 성장에는 실리콘 용탕의 대류를 억제하여 웨이퍼의 순도를 높이기 위해 자기장 특히, 웨이퍼의 성장방향에 수직인 '수평자장'을 인가하는 방법이 사용된다. 현재 '자기장인가 방식', 특히 초전도를 사용한 자장인가 방식이 직경 1600mm에 이르는 용탕의 용액을 제어하는 유일한 방법으로 받아들여지고 있다. 본 논문에서는 12inch 실리콘 웨이퍼 성장용 초전도 마그네트 개발의 전단계로 개발중인 8inch 웨이퍼 성장용 수평자장형 초전도마그네트의 제작과정과 성능평가 결과에 대해 다루었다. 본 연구를 통해 액체헬륨의 증발을 최소화하기 위한 재응축형 극저온 용기에 대한 기술이 개발 되었으며, diode를 이용한 ��치보호부, HTS 전류리드의 ��치 protection부 등의 부속기술이 개발되었다. 초전도 마그네트는 내경 1400mm의 saddle type으로 이의 제작에 있어 많은 기술적 난재들을 경험해야 했다. 전체 시스템에 대한 성능평가 결과, 극저온용기 및 부속장치에 대한 결과는 만족스러웠으나, 코일부의 성능은 계획한 목표에 미치지 못했다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.306-306
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• 2012

사파이어 단결정은 LED 소자의 기판으로 널리 사용되고 있으며 현재 소재 수율을 향상시키기 위하여 6인치 이상의 대구경 웨이퍼를 만들기 위하여 많은 노력을 경주하고 있다. 단결정, 특히 반도체 단결정 웨이퍼에서($00{\cdot}1$), ($11{\cdot}0$) 등의 어떠한 결정학적인 방위(crystallographic orientation)가 표면과 이루는 각도, 즉 표면방위각(off-cut 또는 misorientation angle)의 크기와 방향은 제조된 LED 소자의 물성에 영향을 끼치므로 웨이퍼를 가공할 때 정확하게 컨트롤해야한다. 본 연구에서는 고분해능 X-선을 이용하여 표면이 결정학적 방향과 이루는 면방위각을 정밀하게 결정하는 측정법을 연구하였다. 본 연구에서는 기존의 ASTM 의 측정법과는 다른 원리를 이용하고 웨이퍼의 휨(bending)이나 측정고니오 회전축의 편심과 무관하게 표면방위각을 결정하는 새로운 이론적 모델을 제시하고 그 모델을 적용하여 표면의 수직축이 대구경 사파이어($00{\cdot}1$) 축과 이루는 표면방위각을 정확하게 측정 분석하였다. 그리고 이러한 측정방법의 장점을 이용하여 ASTM의 측정법과 면방위 측정 결과를 비교 분석 하였다. 150 mm 사파이어 웨이퍼를 ASTM의 방법으로 면방위를 측정하였을 때 고분해능 장비에서 회전축 ${\Phi}$의 기준을 다르게 설정함에 따라서 수직/수평 면방위 측정결과가 많은 차이를 보였다. 그러나 본 연구에서 사용한 측정법에서는 이러한 수직/수평 면방위의 값들이 거의 변화하지 않고 일정하게 나타나는 것을 확인 하였으며, 측정한150 mm 사파이어 웨이퍼의 표면방위각은 $0.21^{\circ}$이고 표면각이 나타나는 방향은 웨이퍼의 primary edge 방향으로부터 $1.2^{\circ}$벗어나 있는 방향이었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.321-326
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• 2021

This paper presents a technique to minimize damaged wafers during loading. A thin wafer used in solar cells and semiconductors can be damaged easily. This makes it difficult to separate the wafer due to surface tension between the loaded wafers. A technique for minimizing damaged wafers is to supply compressed air to the wafer and simultaneously apply a small horizontal movement mechanism. The main experimental factors used in this study were the supply speed of wafers, the nozzle pressure of the compressed air, and the suction time of a vacuum head. A higher supply speed of the wafer under the same nozzle pressure and lower nozzle pressure under the same supply speed resulted in a higher failure rate. Furthermore, the damage rate, according to the wafer supply speed, was unaffected by the suction time to grip a wafer. The optimal experiment conditions within the experimental range of this study are the wafer supply speed of 600 ea/hr, nozzle air pressure of 0.55 MPa, and suction time of 0.9 sec at the vacuum head. In addition, the technology improved by the repeatability performance tests can minimize the damaged wafer rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.222-222
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• 2010

수평성장 방식을 이용하여 다결정 실리콘 리본을 제조하였으며, 제조된 리본의 미세구조 및 결함을 분석하였다. 기존 잉곳 성장 및 절단 공정을 통해 제조된 실리콘 웨이퍼는 절단 중 실리콘의 손살 때문에 단가를 상승 시킨다. 따라서 실리콘 용탕으로부터 직접 웨이퍼를 제조하는 리본 기술이 활발히 연구되고 있다. 본 연구에서는 수명 성장 법을 이용하여 용융 실리콘으로부터 다결정 실리콘 리본을 제조 하였다. 제조 된 리본의 크기$50{\times}50$ mm였으며 두께는 $375{\pm}50{\mu}m$ 이었다. 또한, 미세구조 분석 결과 결정들의 형상이 불규칙적 이었으며, 바닥에서부터 윗부분까지 한 방향으로 성장되었다. 수직성장된 결정들의 평균 입경은 $50.2{\mu}m$ 이었다. 전위 (dislocations ), 이중(twins), 그리고 기공 (pores) 같은 구조적 결점들과 SiC, 탄소, 그러고 산소와 같은 불순물 결함 등이 관찰 되었다. 본 연구를 통해 제조된 다결정 실리콘 리본은 태양전지용 웨이퍼로 응용 가능 할 것으로 판단된다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.175-183
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• 1994

To investigate thermophoretic effect on particle deposition, average deposition velocity toward a horizontal wafer surface in vertical airflow is measured keeping the wafer surface temperature different from the surrounding air temperature. In the present measurement, the temperature difference is maintained in the range from -10 to $4^{\circ}$ C Polystyrene latex (PSL) spheres of diameter between 0.3 and 0.8 .mu.m are used for the experiment. The number of particles deposited on a wafer surface is estimated from the measurements using a wafer surface scanner (PMS SAS-3600). Experimental data are compared with prediction model results.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.215-215
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• 2012

Sillicon Wafer는 순도 99.9999999%의 단결정 규소를 사용하여 만들어진다. 웨이퍼의 표면은 결함이나 오염이 없어야 하고 회로의 정밀도에 영향을 미치기 때문에 고도의 평탄도와 정밀도를 요구한다. 특히 실리콘의 순도는 효율성에 영향을 주는 주요 원인으로 금속의 오염은 실리콘 웨이퍼의 수명을 단축시켜 효율성을 떨어뜨린다. 표면에 흡착된 구리와 니켈은 Silicon 오염의 주요인 중 하나로 알려져 있다. 이 연구는 Silicon Wafer 표면에 흡착된 구리가 내부로 확산되는 메커니즘을 규명하는 것을 목표로 한다. 표면에 구리가 흡착된 상태는 AES 및 LEED로 관찰하였다. 표면에 흡착된 구리의 표면(수평)및 내부(수직)확산은 SIMS를 이용하여 연구하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1715-1721
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• 2002

Numerical analysis was conducted to characterize the gas flow field and particle deposition on a horizontal freestanding semiconductor wafer under the laminar flow field at vacuum environment. In order to calculate the properties of gas, the gas was assumed to obey the ideal gas law. The particle transport mechanisms considered were convection, Brownian diffusion and gravitational settling. The averaged particle deposition velocities and their radial distributions fnr the upper surface of the wafer were calculated from the particle concentration equation in an Eulerian frame of reference for system pressures of 1 mbar~1 atm and particle sizes of 2nm~10$^4$ nm(10 ${\mu}{\textrm}{m}$). It was observed that as the system pressure decreases, the boundary layer of gas flow becomes thicker and the deposition velocities are increased over the whole range of particle size. One thing to be noted here is that the deposition velocities are increased in the diffusion dominant particle size range with decreasing system pressure, whereas the thickness of the boundary layer is larger. This contradiction is attributed to the increase of particle mechanical mobility and the consequent increase of Brownian diffusion with decreasing the system pressure. The present numerical results showed good agreement with the results of the approximate model and the available experimental data.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.10
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• pp.1284-1293
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• 1997

The electrostatic effect on particle deposition onto a heated, Horizontal free-standing wafer surface was investigated numerically. The deposition mechanisms considered were convection, Brownian and turbulent diffusion, sedimentation, thermophoresis and electrostatic force. The electric charge on particle needed to calculate the electrostatic migration velocity induced by the local electric field was assumed to be the Boltzmann equilibrium charge. The electrostatic forces acted upon the particle included the Coulombic, image, dielectrophoretic and dipole-dipole forces based on the assumption that the particle and wafer surface are conducting. The electric potential distribution needed to calculate the local electric field around the wafer was calculated from the Laplace equation. The averaged and local deposition velocities were obtained for a temperature difference of 0-10 K and an applied voltage of 0-1000 v.The numerical results were then compared with those of the present suggested approximate model and the available experimental data. The comparison showed relatively good agreement between them.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.350-355
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• 2000

The fabrication of sapphire wafer in C plane has been developed by horizontal Bridgeman method and GaN based semiconductor epitaxial growth has been carried out in metal organic chemical vapour deposition. The single crystalline ingot of sapphire has been utilized for 2 inch sapphire wafers and wafer slicing and lapping machines were designed. These several steps of lapping processes provided the mirror-like surface of sapphire wafer. The measurements of the surface flatness and the roughness were carried out by the atomic force microscope. The GaN thin film growth on the developed wafer was confirmed the wafer quality and applicability to blue light emitting devices.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.5
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• pp.1319-1332
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• 1995

Numerical analysis was performed to characterize the particle deposition behavior on a horizontal free-standing wafer with thermophoretic effect under the turbulent flow field. A low Reynolds number k-.epsilon. turbulence model was used to analyze the turbulent flow field around the wafer, and the temperature field for the calculation of the thermophoretic effect was predicted from the energy equation introducing the eddy diffusivity concept. The deposition mechanisms considered were convection, diffusion, sedimentation, turbulence and thermophoresis. For both the upper and lower surfaces of the wafer, the averaged particle deposition velocities and their radial distributions were calculated and compared with the laminar flow results and available experimental data. It was shown by the calculated averaged particle deposition velocities on the upper surface of the wafer that the deposition-free zone, where the deposition velocite is lower than 10$^{-5}$ cm/s, exists between 0.096 .mu.m and 1.6 .mu.m through the influence of thermophoresis with positive temperature difference of 10 K between the wafer and the ambient air. As for the calsulated local deposition velocities, for small particle sizes d$_{p}$<0.05 .mu.m, the deposition velocity is higher at the center of the wafer than at the wafer edge, whereas for particle size of d$_{p}$ = 2.0 .mu.m the deposition takes place mainly on the inside area of the wafer. Finally, an approximate model for calculating the deposition velocities was recommended and the calculated deposition velocity results were compared with the present numerical solutions, those of Schmidt et al.'s model and the experimental data of Opiolka et al.. It is shown by the comparison that the results of the recommended model agree better with the numerical solutions and Opiolka et al.'s data than those of Schmidt's simple model.