• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.114-114
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• 1999

Boron nitride (BN)는 매우 뛰어난 물리적, 화학적 성질을 가지고 있는 재료로 많은 연구가 진행되고 있다. hexagonal 형태의 hBN의 경우 큰 전기 저항과 열 전도도를 가지고 있고 열적 안정성을 가지고 있어 반도체 소자에서 절연층으로 쓰일 수 있다. 또한 X-ray와 가시광선을 투과시키기 때문에 X-ray와 가시광선을 투과시키기 때문에 X-ray lithography이 mask 기판으로 사용될 수 있다. Boron-carbon-nitrogen (BCN) 역시 뛰어난 기계적 성질과 투명성을 가지고 있어 보호 코팅이나 X-ray lithography에 이용될 수 있다. 또한 원자 조성이나 구성을 변화시켜 band gap을 조절할 수 있는 가능성을 가지고 있기 때문에 전기, 광소자의 재료로 이용될 수 있다. 본 연구에서는 여러 합성 조건 변화에 따른 hBN 막의 합성 거동을 관찰하고, 카본 농도변화에 따른 BCN 막의 기계적 성질과 구조의 변화, 그리고 실리콘 첨가에 의한 물성 변화를 관찰하였다. BN박막은 실리콘 (100) 기판 위에 r.f. plasma assisted CVD를 이용하여 합성하였다. 합성 압력 0.015 torr, 원료 가스로 BCl3 1.5 sccm, NH3 6sccm을 Ar 15 sccm을 사용하여 기판 bias (-300~-700V)와 합성온도 (상온~50$0^{\circ}C$)를 변화시켜 BN막을 합성하였다. BCN 박막은 상온에서 기판 bias를 -700V로 고정시킨 후 CH4 공급량과 Ar 가스의 첨가 유무를 변화시켜 합성하였다. 또한 SiH4 가스를 이용하여 실리콘을 함유하는 Si-BCN 막을 합성하였다. 합성된 BN 막의 경우, 기판 bias와 합성 온도가 증가할수록 증착속도는 감소하는 경향을 보여 주었다. 기판 bias와 합성온도에 따른 구조 변화를 SEM과 Xray로 분석하였다. 상온에서 합성한 경우는 표면형상이 비정질 형태를 나타내었고, X-ray peak이 거의 관찰되지 않았다. 합성온도가 증가하게 되면 hBN (100) peak이 나타나게 되고 이것은 합성된 막이 turbostratic BN (tBN) 형태를 가지고 있다는 것을 나타낸다. 50$0^{\circ}C$의 합성 온도에서 기판 bias가 -300V에서 hBN (002) peak이 관찰되었고, -500, -700 V에서는 hBN (100) peak만이 관찰되었다. 따라서 고온에서의 큰 ion bombardment는 합성되는 막의 결정성을 저해하는 요소로 작용한다는 것을 확인 할 수 있었다. 합성된 BN 막은 ball on disk type의 tribometer를 이용하여 마모 거동을 관찰한 결과 대부분 1이상의 매우 큰 friction coefficient를 나타내었고, nano-indenter로 측정한 BN막의 hardness는 매우 soft한 막에서부터 10 GPa 정도 까지의 값을 나타내었고, nano-indenter로 측정한 BN 막의 hardness는 매우 soft한 막에서부터 10GPa 정도 까지의 값을 가지며 변하였다. 합성된 BCN, Si-BCN 막은 FT-IR, Raman, S-ray, TEM 분석을 통하여 그 구조와 합성된 상에 관하여 분석하였다. FT-IR 분석을 통해 B-N 결합과 C-N 결합을 확인할 수 있었고, Raman 분석을 통하여 DLC의 특성을 분석하였다. 마모 거동에서는 BCN 막의 경우 0.6~0.8 정도의 friction coefficient를 나타내었고 Si-BCN 막은 0.3이하의 낮은 friction coefficient를 나타내었다. Hardness는 carbon의 함유량과 Ar 가스의 첨가 유무에 따라 각각을 측정하였고 이것은 BN 막 보다 향상된 값을 나타내었다.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.29-32
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• 2009

Dense and periodic arrays of nano-sized holes were patterned in oxide thin film on GaAs substrate. To obtain the nano-size patterns, self-assembling diblock copolymer was used to produce thin film of uniformly distributed parallel cylinders of polymethylmethacrylate (PMMA) in polystyrene (PS) matrix. The PMMA cylinders were removed with UV expose and acetic acid rinse to produce PS nanotemplate. By reactive ion etching, pattern of the PS template was transferred to under laid silicon oxide layer. Transferred patterns were reached to the GaAs substrate by controlling the dry etching time. We confirmed the achievement of etching through the removing oxide layer and observation of GaAs substrate surface. Optimized etching time was 90 to 100 sec. Pore sizes of the nanopattern in the silicon oxide layer were 20~22 nm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.379-382
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• 2007

The MEMS (Micro Electro Mechanical Systems) process is used in a micro/nano pattern manufacturing method. This method is based on the lithography technology. But the MEMS process has some problems such as complicated process, long processing time and high production costs. Many researchers are doing research in substitute manufacturing method to work out a solution to these problems. In this paper, we apply a dieless incremental forming technology to a substitute method of MEMS process. This dieless forming technology is using in the commercial scale sheet forming such as a prototype of automobile sheet parts. 5-axes CNC (Computerized Numeric Control) method are applied in this system to get a micro-scale dieless forming results. These 5-axes system are composed of precision AC servo motor stages (4-axes) and PZT actuator (1-axis). A PZT actuator is used in a precision actuating axis because it can be operated in the nano scale stroke resolution. This micro dieless incremental forming system has the advantage of minimization in manipulating distance and working space. As equipment and tools become smaller in size, minute inertia force and high natural frequency can be obtained. Therefore, high precision forming performance can be obtained. This allows the factory to quickly provide the customer with goods because the manufacturing system and process are reduced. To construct this micro manufacturing system, many technologies are necessary such as high stiffness frame, high precision actuating part, structural analysis, high precision tools and system control. To achieve the optimal forming quality, the micro dieless forming system is designed and made with high stiffness characteristic.

• Journal of IKEEE
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• v.13 no.2
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• pp.126-131
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• 2009

To overcome short channel effects, wrap-around field effect transistors have drawn a great deal of attention for their superior electrostatic coupling between the channel and the surrounding gate electrode. In this paper, we introduce a bottom-up technique to fabricate a wrap-around field effect transistor using silicon nanowires as the conduction channel. Device fabrication was consisted mainly of electron-beam lithography, dielectrophoresis to accurately align the nanowires, and the formation of gate electrode using electrochemical deposition. The electrolyte for electrochemical deposition was made up of non-toxic organic-based solution and liquid nitrogen was used as a method of maintaining the shape of polymethyl methacrylate(PMMA) during the process of electrochemical deposition. Patterned PMMA can be used as a nano-template to produce wrap-around gate nano-structures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.875-881
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• 2004

Fundamental results obtained from an atomic force microscope (AFM) chemically-induced direct nano-lithography process are presented, which is regarded as a simple method for fabrication nm-scale devices such as superconducting flux flow transistors (SFFTs) and single electron tunneling transistors (SETs). Si cantilevers with Pt coating and with 30 nm thick TiO coating were used as conducting AFM tips in this study. We observed the surfaces of superconducting strip lines modified by AFM anodization' process. First, superconducting strip lines with scan size 2 ${\mu}{\textrm}{m}$${\times}$2 ${\mu}{\textrm}{m}$ have been anodized by AFM technology. The surface roughness was increased with the number of AFM scanning, The roughness variation was higher in case of the AFM tip with a positive voltage than with a negative voltage in respect of the strip surface. Second, we have patterned nm-scale oxide lines on ${YBa}-2{Cu}_3{O}_{7-x}$ superconducting microstrip surfaces by AFM conductive cantilever with a negative bias voltage. The ${YBa}-2{Cu}_3{O}_{7-x}$ oxide lines could be patterned by anodization technique. This research showed that the critical characteristics of superconducting thin films were be controlled by AFM anodization process technique. The AFM technique was expected to be used as a promising anodization technique for fabrication of an SFFT with nano-channel.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.4
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• pp.385-390
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• 2011

In this study, we developed a micromixer based on the non-equilibrium electrokinetics at the junction of a microchannel and nanochannel. Two fluid streams were mixed by an electro-osmotic flow and a vortex flow created as a result of the non-equilibrium electrokinetics at the junction of the microchannel and nanochannel. Initially, the microchannel was fabricated using Polydimethylsiloxane (PDMS) by the general soft lithography process and the nanochannel was created at a specific position on the microchannel by applying a high voltage. To evaluate the mixing performance of the micromixer, fluorescent distribution was analyzed by using the fluorescent dye, Rhodamine B. About 90% mixing was achieved with this novel micromixer, and this micromixer can be used in microsystems for biochemical sample analysis.

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.107-112
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• 2016

In this paper, the hydrophobic rough surfaces were prepared by employing a conventional nano-imprint lithography technique, and the effects of surface parameter, ratio of the top surface to the flat unit cell, on the impingement behaviors of liquid droplet were investigated to improve robustness of hydrophobic functionality. The critical height defined for the transition from rebound to fragmentation is measured by droplet impingement test in order to study dynamic behavior of an impinged droplet. It showed the critical height decreased with high surface parameter while it increased with low surface parameter. However, the critical height decreased again as surface parameter decreased further. Observed results suggest that the optimized surface pattern should be designed for the increased critical height.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.633-642
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• 2008

It's important to measure quantitative properties about thermal-nano behavior of polymer for producing high quality components using Nanoimprint lithography process. Nanoscale indents can be used to make the cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, formability of polymethylmetacrylate(PMMA) and polycarbonate(PC) were characterized Polymer has extreme variation in thermo mechanical variation during forming high temperature. Because of heating the polymer, it becomes softer than at room temperature. In this case it is particularly important to study high temperature-induced mechanical properties of polymer. Nanoindenter XP(MTS) was used to measure thermo mechanical properties of PMMA and PC. Polymer was heated by using the heating stage on NanoXP. At CSM(Continuous Stiffness Method) mode test, heating temperature was $110^{\circ}C,120^{\circ}C,130^{\circ}C,140^{\circ}C$ and $150^{\circ}C$ for PMMA, $140^{\circ}C,150^{\circ}C,160^{\circ}C,170^{\circ}C$ and $180^{\circ}C$ for PC, respectively. Maximum indentation depth was 2000nm. At basic mode test, heating temperature was $90^{\circ}C$ and $110^{\circ}C$ for PMMA, $140^{\circ}C,160^{\circ}C$ for PC. Maximum load was 10mN, 20mN and 40mN. Also indented pattern was observed by using SEM and AFM. Mechanical properties of PMMA and PC decreased when temperature increased. Decrease of mechanical properties from PMMA went down rapidly than that of PC.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.25-29
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• 2012

The properties of carbon nanotube-metal hybrid nanostructures are critically dependent on the structure and chemistry of the metal-carbon nanotube interface. In this study, the interface between nickel and multi-walled carbon nanotubes (CNTs) has been investigated using physical vapor-deposited (sputter-deposited) nickel onto the surface of freestanding carbon nanotube arrays processed by nano-imprint lithography (NIL). These interfaces have been characterized by transmission electron microscopy and 3D atom probe tomography. In the nickel nanocrystals growing on the CNT surface, a metastable hexagonal $Ni_3C$-types phase appears to be stabilized. The structural stability of the nickel-CNT interface is also discussed and related to potential implications for the properties of these nanocomposites.

• Journal of Biomedical Engineering Research
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• v.40 no.5
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• pp.165-170
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• 2019

Cancer cells are different from normal cells in terms of life cycle, behavior, and growth patterns. Cancer cells can migrate freely in the body through blood vessels and lymph nodes. The cancer cells easily interact with various substrates including extracellular matrix and vessels and they can differentiate in the new environment. However, it is not well known about the adhesion preference of cancer cells on the substrate and the mechanism of their interaction. In this study, we prepared the nano-, micro-patterned substrates using E-beam lithography techniques. MCF-7 cells were tested on the substrates to find out their adhesion preference. The substrates were made by polydimethylsiloxane (PDMS) with specific patterns including pillars with a diameter of 500 nm, 700 nm, $3{\mu}m$ and $5{\mu}m$. MCF-7 cells were seeded on the substrates and incubated for 24 hours. As a result, this study clearly demonstrated that the MCF-7 cells preferred 700 nm patterning.