• Journal of the Semiconductor & Display Technology
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• v.6 no.3
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• pp.25-33
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• 2007

A computationally efficient and accurate Monte Carlo (MC) simulator of electron beam lithography process, which is named SCNU-EBL, has been developed for semiconductor nanometer pattern design and fabrication. The simulator is composed of a MC simulation model of electron trajectory into solid targets, an Gaussian-beam exposure simulation model, and a development simulation model of photoresist using a string model. Especially for the trajectories of incident electrons into the solid targets, the inner-shell electron scattering of an target atom and its discrete energy loss with an incident electron is efficiently modeled for multi-layer resists and heterogeneous multi-layer targets. The simulator was newly applied to the development profile simulation of ZEP520 positive photoresist for NGL(Next-Generation Lithography). The simulation of ZEP520 for electron-beam nanolithography gave a reasonable agreement with the SEM experiments of ZEP520 photoresist.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.379-379
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• 2011

차세대 저항메모리(resistive switching random access memory; ReRAM)의 개발을 위해 다양한 산화 물질들의 저항 변화 특성이 연구되고 있다. 본 연구에서는 저항 변화 물질로 잘 알려진 ZnO 박막을 이용하여 저항 변화 특성을 평가하였다. ZnO 박막은 Pt/Ti/$SiO_2$/Si 기판 위에 스퍼터링 시스템을 이용하여 약 50 nm 두께로 증착되었다. 증착된 박막 위에 전극을 evaporator를 이용하여 패턴닝함으로써 전극-반도체-전극 구조의 소자를 만들고 이의 전기적 특성을 평가하였다. Compliance current를 설정하여 저항 변화 특성을 측정한 결과 가해진 전압의 극성에 관계 없이 저항이 변화하는, dielectric breakdown에 의해 박막내 전도성 필라멘트라 불리는 전도성 길이 생성되었다가 joule-heating에 의해 필라멘트가 파열되는, 전형적인 unipolar 저항 변화특성이 나타났다. 다기능성 소자 개발을 위해 위 소자 구조를 투명한 고분자 기판위에 형성하고 표면에 초발수성 ZnO 나노막대 구조를 합성하였다. 그 결과 투명하면서 유연하고, 수분에도 안정적인 다기능성 저항 변화 소자 특성을 평가할 수 있었다. 본 결과를 바탕으로 필라멘트 이론에 기초한 저항 변화 메커니즘을 설명하는 모델이 제시되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.329-329
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• 2008

Silver nanoparticles were synthesized by polyol process and its particle size observed with TEM is about 20nm. Silver nanoparticle ink with metal content of 30wt% was prepared using solvent of ethanol and has low viscosity of 5cps (10rpm). This ink was printed by as ink-jet printer on Al2O3 and Silicone substrate. The resistivity and morphology of the printed film was investigated as a function of sintering termperature.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.989-992
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• 2004

A new method is proposed to fabricate a reusable qualtz master with order of 100 nm dot pattern on its surface. Some fabrication conditions such as dose are investigated to find optimal condition. This reusable qualtz master is used directly as a stamper to injection mold the dot patterns. Polycarbonate and Polyoxymethylene are used as molding materials and the effect of the mold temperature is also investigated to see the moldabilty of the injection molding for very fine dot features.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.164-165
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• 2007

Si(중간층)/DLC(diamond-like carbon)막은 스퍼터와 이온소스(ion source)법에 의한 복합방식(hybrid method)을 이용하여 3mTorr의 반응가스 벤젠($C_6H_6$)분위기에서 Si wafer에 기판온도 $130^{\circ}C$로 180분간 증착하였다. 평가는 표면과 단면에 대해 주사전자현미경(scanning electron microscopy, SEM)과 투자전자현미경(trasmission electron microsope, TEM)으로 관찰하였다. 경도와 마찰계수는 나노인텐터(nanoindetor)와 마모시험기를 이용하였으며, 박막의 구조는 라만스펙트럼으로 분석하였다. 그 결과 박막의 두께는 약 $0.9{\mu}m$, 표면조도는 약 $0.34{\sim}1.64nm$로 평탄한 표면을 가지며 경도는 약 $35{\sim}37GPa$, 마찰계수는 약 $0.02{\sim}0.07$로 관찰되었다. 라만분광법과 전자회절패턴에 의해 IG/ID의 함량비는 $0.54{\sim}0.59$로 $sp^2$와 $sp^3$가 혼재된 전형적인 비정질 구조임을 확인하였다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.60-63
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• 2005

In this paper, we investigated the possibility of replicating patterned media by nano-injection molding process with a metallic nano-stamper. The original nano-master was fabricated by E-beam lithography and ICP etching process. The metallic nano-stamper was fabricated using a nanoimprint lithography and nano-electroforming process. Finally, the nano-patterned substrate was replicated using a nano-injection molding process without additional etching process. The replicated patterns using nano-injection molding process were as small as 50 nm in diameter, 150 nm in pitch, and 50 nm in depth.

• Transactions of Materials Processing
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• v.33 no.4
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• pp.291-300
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• 2024

To compare the lubrication performance improvement of different laser texturing surface treatment patterns, ring-shaped specimens were prepared by processing line and dot patterns using a fiber laser device. Ring compression tests were conducted to compare the reduction rates of the inner diameter corresponding to the same height reduction of the specimens. Laser processing conditions were set to create patterns with a depth of 9㎛ and a width of 45㎛. Ring specimens were processed with varying spacings between dots and lines. The forging lubricant TECTYL FORM CF 351S was uniformly applied to the upper and lower compression tools, and the rings were compressed by 40% using a hydraulic press, after which the inner diameter was measured. The comparison of inner diameter reduction rates indicated that pattern processing improves lubrication performance, with line patterns being more effective than dot patterns in enhancing lubrication performance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.96-101
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• 2017

We have developed a compact desktop-sized nanopatterning system driven by the Roll-to-Roll (R2R) nanoimprinting (NIL) principle. The system realizes the continuous and high-speed stamping of various nanoscale patterns on a large-area flexible substrate without resorting to ponderous and complicated instruments. We first lay out the process principle based on continuous NIL on a UV-curable resin layer using a flexible nanopatterned mold. We then create conceptual and specific designs for the system by focusing on two key processes, imprinting and UV curing, which are performed in a continuous R2R fashion. We build a system with essential components and optimized modules for imprinting, UV curing, and R2R conveying to enable simple but effective nanopatterning within the desktop volume. Finally, we demonstrate several nanopatterning results such as nanolines and nanodots, which are obtained by operating the built desktop R2R NIL system on transparent and flexible substrates. Our system may be further utilized in the scalable fabrication of diverse flexible nanopatterns for many functional applications in optics, photonics, sensors, and energy harvesters.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.3
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• pp.83-90
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• 2019

In this paper, Mg-doped AlN epilayers for power semiconductor devices are grown by mixed-source hydride vapor phase epitaxy. Magnesium is used as p-type dopant material in the grown AlN epilayer. The AlN epilayers on the GaN-templated sapphire substrate and GaN-templated-patterned sapphire substrate (PSS), respectively, as the base substrates for device application, were selectively grown. The surface and the crystal structures of the AlN epilayers were investigated by field emission scanning electron microscopy (FE-SEM) and high-resolution-X-ray diffraction (HR-XRD). From the X-ray photoelectron spectroscopy (XPS) and Raman spectra results, the p-type AlN epilayers grown by using the mixed-source HVPE method could be applied to power devices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.6
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• pp.226-231
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• 2020

Polyvinyl pyrrolidone nanofibers including nickel, zinc, and iron precursors were fabricated via the electrospinning method. To convert as-spun nanofibers to Ni0.5Zn0.5Fe2O4 oxide nanof ibers which is capable of shielding an electromagnetic wave, heat treatment conditions were optimized. To obtain the heat treatment condition that can exclude amorphous carbon black and secondary crystal phase, samples were taken at each temperature while the calcination process and analyzed. According to the X-ray diffraction (XRD) analysis, the Ni0.5Zn0.5Fe2O4 crystal phase started to appear from 300℃, but it was confirmed through energy dispersive spectroscopy (EDS) analysis that heat treatment of 500℃ or more was required to remove most of the carbon black. When the calcination temperature exceeds 650℃, crystal nuclei starts to grow and the fiber surface condition becomes rough, so it was confirmed that the heat treatment conditions should be selectively determined according to the application field.