• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1631-1636
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• 2010

In this study, we demonstrate a nano-scale lithograph obtained on localized (100) silicon (p-type) surface using by modified AFM (Atomic force microscope) apparatuses and by adopting controlling methods. AFM-based experimental apparatuses are connected to a customized pulse generator that supplies electricity between the conductive tip and the silicon surface, while maintaining a constant humidity throughout the lithography process. The pulse durations are controlled according to various experimental conditions. The electrochemical reaction induced by the pulses occurs in the gap between the conductive tip and silicon surface and result in the formation of nanoscale oxide particles. Oxide particles with various heights and widths can be created by AFM surface modification; the size of the oxide particle depends on the pulse durations and the applied electrical conditions under a humid environment.

• Journal of the Korean Magnetics Society
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• v.23 no.4
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• pp.126-129
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• 2013

We have fabricated an ordered Ni nanodot structure using an alumina mask prepared via 2-step anodization technique under phosphoric acid. We have formed a porous structure with average pore size of 279 nm on $2{\mu}m$ thick alumina film and the thermal deposition of thin Ni film though the mask led to the formation of ordered Ni nanodot structure with an average dot size of 293 nm, following the pore structure on the mask. We further investigated the magnetic properties of the nanodot structure by measuring the hysteresis curve at room temperature. When compared to the magnetic properties of a continuous Ni film, we observed the decrease in the squareness and the increase in coercivity along the magnetization easy axis, due to the isolated nanodot structure. Our study suggests that the ordered nanodot structure can be easiy fabricated with thin film deposition technique using anodized alumina mask as a mask.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1099-1103
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• 2007

TFT's have been intensively researched for possible electronic and display applications. Through tremendous engineering and scientific efforts, a-Si:H TFT fabrication process was greatly improved. In this paper, the reason on defects occurring at a-Si:H TFT fabrication process is analyzed and solved, so a-Si:H TFT's yield is increased and reliability is improved. The a-Si:H TFT of this paper is inverted staggered type TFT. The gate electrode is formed by patterning with length of $8{\mu}m{\sim}16{\mu}m$ and width of $80{\sim}200{\mu}m$ after depositing with gate electrode (Cr). We have fabricated a-SiN:H, conductor, etch-stopper and photo-resistor on gate electrode in sequence, respectively. We have deposited n+a-Si:H, NPR(Negative Photo Resister) layer after forming pattern of Cr gate electrode by etch-slower pattern. The NPR layer by inverting pattern of upper Sate electrode is patterned and the n+a-Si:H layer is etched by the NPR pattern. The NPR layer is removed. After Cr layer is deposited and patterned, the source-drain electrode is formed. The a-Si:H TFT made like this has problems at photo-lithography process caused by remains of PR. When sample is cleaned, this remains of PR makes thin chemical film on surface and damages device. Therefor, in order to improve this problem we added ashing process and cleaning process was enforced strictly. We can estimate that this method stabilizes fabrication process and makes to increase a-Si:H TFT's yield.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.1
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• pp.47-54
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• 2021

For the bonding of smaller PCB solder bumps of less than 100 microns, an experiment was performed to make up a tin plating solution and find plating conditions in order to produce a bump pattern through tin electroplating, replacing the previous PCB solder bumps process by microballs. After SR patterning, a Cu seed layer was formed, and then, through DFR patterning, a pattern in which Sn can be selectively plated only within the SR pattern was formed on the PCB substrate. The tin plating solution was made based on methanesulfonic acid, and hydroquinone was used as an antioxidant to prevent oxidation of divalent tin ions. Triton X-100 was used as a surfactant, and gelatin was used as a grain refiner. By measuring the electrochemical polarization curve, the characteristics of organic additives in Triton X-100 and gelatin were compared. It was confirmed that the addition of Triton X-100 suppressed hydrogen generation up to -1 V vs. NHE, whereas gelatin inhibited hydrogen generation up to -0.7 V vs. NHE. As the current density increased, there was a general tendency that the grain size became finer, and it was observed that it became finer when gelatin was added.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.105-112
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• 2018

This paper proposes a method for fabricating heatable glass using the conduction characteristics of metal thin films deposited on the surface of Low-e(Low emissivity) glass. The heating value of Low-e glass depends on the Joule heat caused by Low-e glass sheet resistance. Hence, its prediction and design are possible by measuring the sheet resistance of the material. In this study, silver electrodes were placed at 50 mm intervals on a soft Low-e glass sample with a low emissivity layer of 11 nm. This study measured the sheet resistance using a 4-point probe, predicted the power consumption and heating value of the Low-e glass, and confirmed the heating performance through fabrication and experience. There are two conventional methods for manufacturing heatable glass. One is a method of inserting nichrome heating wire into normal glass, and the other is a method of depositing a conductive transparent thin film on normal glass. The method of inserting nichrome heating wire is excellent in terms of the heating performance, but it damages the transparency of the glass. The method for depositing a conductive transparent thin film is good in terms of transparency, but its practicality is low because of its complicated process. This paper proposes a method for manufacturing heatable glass with the desired heating performance using Low-e glass, which is used mainly to improve the insulation performance of a building. That is by emitting a laser beam to the conductive metal film coated on the entire surface of the Low-e glass. The proposed method is superior in terms of transparency to the conventional method of inserting nichrome heating wire, and the manufacturing process is simpler than the method of depositing a conductive transparent thin film. In addition, the heat characteristics were compared according to the patterning of the surface thin film of the Low-e glass by an emitting laser and the laser output conditions suitable for Low-e glass.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.738-742
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• 2012

Here, we develop a new nanofilter device for the rapid and efficient separation of nanoparticles and biomolecules, exploiting the use of AAO mebrane with ordered nanopores in the range from 20 nm to 200 nm. Briefly, the chip comprises of a series of the upper and lower PDMS channels containing embedded inlet and outlet ports, and $50{\mu}m$ width microfluidic channel, and AAO membrane to be made the filtering zone. After assembling these components, the acrylate plastic plates were used to fix the device on the top and bottom side. When introducing the samples into the inlet ports of the upper PDMS channel, we were able to separate and concentrate the nanoparticles and target molecules at the filtering zone, and to elute the solutions containing the unwanted materials toward the lower PDMS channels normal to the direction of AAO membrane. To demonstrate the usefulness of the device we apply it to the SERS detection of nucleic acid sequences associated with Dengue virus serotype 2. We report a limit of detection for Dengue sequences of 300 nM and show excellent enhancement of Raman signals from the filter zone of the nanofilter device.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.23-27
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• 2004

The $Al_xTa_{1-x} (x=0.0{\~}1.0)$ alloy thin films were deposited by RF-magnetron sputtering system, and the crystal quality, surface morphology, and electrical properties were examined using XRD, AFM, 4-point probe techniques in this study. The thin films were grown according to the alloy compositions first, and the effects of film thickness and mask patterns were investigated afterwards. Also, the heating characteristics were examined by heat controller. The obtained results showed that the high electrical resistivity was obtained for Al content $x=6.63at\%$, and the even higher resistivity was accomplished for the samples with smaller thickness and narrower width. The heating temperature demonstrated the identical trend to the electrical properties, and the highest heating temperature ($400^{\circ}C$) and output power ($12.6W/cm^2$) were obtained for the sample with Al content $x=6.63\%$, film thickness d=500 nm, film width w=1.5 mm.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.81.1-81.1
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• 2012

나노임프린트 리소그라피(Nano-Imprint Lithography, NIL) 기술은 기판위의 resin을 나노구조물이 각인된 스탬프로 눌러서 나노구조물을 형성하는 기술로, 경제적이고 효과적으로 나노구조물을 제작할 수 있는 기술이다. 그중에서도 UV 기반의 나노임프린트(UV-NIL) 기술은 resin을 투명한 스탬프로 누른뒤 UV로 경화시켜 나노구조물을 형성하는 기술로써 고온, 고압($140{\sim}180^{\circ}C$, 10~30bar)이 필요한 가열식 나노임프린트 기술에 비해 상온, 상압($20^{\circ}C$, 1bar)에서도 구조물 형성이 가능하여 다층구조 형성에 적합하다. 연속적인 임프린팅 공정에 의해 resin이 quarz 스탬프에 잔류하여 패터닝에 결함을 유발하게 되므로 오염물을 제거하기 위한 세정공정이 필요하다. 하지만 UV에 의해 경화된 resin은 cross-linking을 형성하여 화학적인 내성이 증가하게 되므로 제거하기가 어렵다. 현재는 resin 제거를 위한 세정공정으로 SPM($H_2SO_4/H_2O_2$) 세정이 사용되고 있는데 세정시간이 길고 세정 후에 입자 또는 황 잔유물이 남으며 많은 유해용액 사용의 문제점이 있어 효과적으로 resin을 제거할 세정공정이 필요한 상황이다. 본 연구에서는 친환경적인 UV 세정 및 오존수 세정공정을 적용하여 경화된 resin을 제거하는 연구를 진행하였다. 실험샘플은 약 100nm 두께의 resin을 증착한 $1.5cm{\times}1.5cm$ $SiO_2$ 쿠폰 wafer를 사용하였으며, UV 및 오존수의 처리시간을 달리하여 resin 제거효율을 평가하였다. ATR-FTIR 장비를 사용하여 시간에 따른 resin의 두께를 측정한 결과, UV 세정으로 100nm 높이의 resin중에 80nm의 bulk resin이 단시간에 제거가 되었고 나머지 20nm의 resin thin film은 오존수 세정으로 쉽게 제거되는 것을 확인 하였다. 또한 표면에 남은 resin residue와 particle을 제거하기 위해서 SC-1 세정을 진행하였고 contact angle과 optical microscope 장비를 사용하여 resin이 모두 제거된 것을 확인하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.51.2-51.2
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• 2009

본 실험에서는 레이저 간섭 리소그래피를 이용한 2차원 나노 패턴을 형성하였고, 수열합성법을 이용하여 90 도에서 ZnO 나노 기둥을 ZnO/Si 기판 상에 제작 하였다. ZnO 버퍼층은 스퍼터를 이용하여 200도, Ar 분위기에서 증착 하였으며, 레이저 간섭 리소그래피를 이용하여 두 번의 노광을 통해 2차원 나노 패턴을 형성하였다. 먼저, 최적화된 포토레지스트를 ZnO/Si 기판 위에 도포하고, 2500rpm에서 30초간 스핀코팅 한 후, 첫번째 노광을 실시 하였고, ZnO/Si 기판을 회전시켜 첫번째 노광과 교차 시킨 다음 두 번째 노광을 통해 교차하는 부분만 현상되도록 하였다. 기판의 회전 및 기판과 입사 레이저 사이의 각도를 조절하여 제작된 나노 패턴의 종류는 square lattice, centered rectangular lattice, oblique lattice, hexagonal lattice, rectangular lattice, 5가지로, 2차원의 모든 격자를 제작 하였다. 저온 수열합성법에서는 Na citrate를 형상제어제 (surfactant ions)로 사용하여 ZnO 나노 기둥을 형성하였다. $NH_4OH$를 이용하여 용액의 pH를 조절하였고, Zn nitrate hexahydrate를 Zn의 원료 물질로 사용하였다. 2차원 나노 패턴의 3차원 형태는 Atomic force microscopy (AFM, Veeco instruments, USA)를 이용하여 접촉 모드에서 관찰하였고, ZnO 나노 구조는 주사 전자 현미경 (FE-SEM, Model: JSM-6701F, Tokyo, Japan) 를 통하여 분석 하였다. 나노 패턴의 AFM 분석 결과 ZnO/Si 기판상에 포토레지스트가 주기적인 배열을 가지는 것을 확인하였고, ZnO/Si 기판상에 포토레지스트가 완전히 현상된 부분이 일정한 배열을 가지는 것을 확인하였다. 포토레지스트가 현상되어 기판의 표면이 드러난 부분의 크기는 약 250nm로 측정되었다. ZnO 나노 구조의 FE-SEM 분석 결과, 각각의 나노 구조가 나노패턴 중 완전히 현상된 부분만을 통하여 성장되었다는 것을 확인하였고, 형상 제어제로 사용된 Na citrate의 첨가 여부에 따라 나노 구조의 모양이 변화되었다는 것을 알 수 있었다. Na citrate 가 첨가된 나노 기둥의 경우 약 500nm의 길이를 가지는 하나의 기둥 형태로 성장하였다는 것을 확인하였다.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.223-228
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• 2016

In this study, we described a simple and facile method to generate uniform microwells poly(dimethyl siloxane) (PDMS) microstamps through micro-molding for efficient, rapid and reliable cell patterning of adipocyte differentiation. In contrast to the conventional methods, the microstamp technologies are low expensive, non-toxic, and using a small amount of solution. Recently, Orlistat known as tetrahydrolipstatin is a prescription drug designed to treat obesity which is used to aid in weight loss and help to reduce overweight obesity. Here, 3T3-L1 cells were treated under various concentration manners of Orlistat $0.2{\mu}M{\sim}5.0{\mu}M$. and it was confirmed maximum 26.5% inhibition activity compared to control. Thus, we elucidated this platform can be used for the real-time analyzing of cell proliferation, adipocyte differentiation for evaluation of anti-obesity agents on cell chip. Furthermore, we except that this platform technology designed here might be readily be expanded to discover a wider variety of anti-obesity agents.