• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.45-52
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• 2009

The research on miniature devices based on non-silicon materials, in particular polymeric materials has been attracting more and more attention in the research field of the micro/nano fabrication in recent years. Lost of applications and many literatures have been reported. However, the study on the micro thermal imprint process of glassy polymer is still not systematic and inadequate. The aim of this research I to obtain a numerical material model for an amorphous glassy polymer, polycarbonate (PC), which can be used in finite element analysis (FEA) of the micro thermal imprint process near the glass transition temperature (Tg). An understanding of the deformation behavior of the PC specimens was acquired by performing tensile stress relaxation tests. The viscoelastic material model based on generalized Maxwell model was introduced for the material near Tg to establish the FE model based on the commercial FEA code ABAQUS/Standard with a suitable set of parameters obtained for this material model form the test data. As a result, the feasibility of the established viscoelastic model for PC near Tg was confirmed and this material model can be used in FE analysis for the prediction and improvement of the micro thermal imprint process for pattern replication.

• Macromolecular Research
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• v.17 no.3
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• pp.181-186
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• 2009

We fabricated ordered micro/nano patterns induced by controlled dewetting on the topographically patterned PS/P4VP bilayer thin film. The method is based on utilizing microimprinting lithography to induce a topographically heterogeneous bilayer film that allows the controlled dewetting upon subsequent thermal annealing. The dewetting that was initiated strictly at the boundary of the thicker and thinner regions was guided by the presence of the topographic structure. The dewetting front velocity of the microdomains in the confined regions was linearly proportional to the measurement time, which enabled us to control the size of the dewet domain with annealing time. In particular, the submicron sized dot arrays between lines were generated with ease when the dewetting was confined into geometry with a few microns in size. The kinetically driven, non-lithographical pattern structures accompanied the pattern reduction to 400%. The pattern arrays on a transparent glass substrate were especially useful for non-circular microlens arrays where the focal length of the lens was easily tunable by controlling the thermal annealing.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.18-23
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• 2024

Nanoimprint lithography (NIL) is widely used to form structures ranging from micro to nanoscale due to its advantage of generating high-resolution patterns at a low process cost. However, most NIL processes require the use of imprint resists and external elements such as ultraviolet light or heat, necessitating additional post-processes like etching or metal deposition to pattern the target material. Furthermore, patterning on flexible and/or non-planar films presents significant challenges. This study introduces an extreme pressure imprint lithography (EPIL) process that can form micro-/nano-scale patterns on the surface of a flexible rubber magnet composite (RMC) film at room temperature without an etching process. The EPIL technique can form ultrafine structures over large areas through the plastic deformation of various materials, including metals, polymers, and ceramics. In this study, we demonstrate the process and outcomes of creating a variety of periodic structures with diverse pattern sizes and shapes on the surface of a flexible RMC composed of strontium ferrite and chlorinated polyethylene. The EPIL process, which allows for the precise patterning on the surface of RMC materials, is expected to find broad applications in the production of advanced electromagnetic device components that require fine control and changes in magnetic orientation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.326-329
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• 2005

As a flexible method to fabricate sub-micrometer patterns, Focused Ion Beam (FIB) instrument and Self-Assembled Monolayer (SAM) resist are introduced in this work. FIB instrument is known to be a very precise processing machine that is able to fabricate micro-scale structures or patterns, and SAM is known as a good etch resistance resist material. If SAM is applied as a resist in FIB processing fur fabricating nano-scale patterns, there will be much benefit. For instance, low energy ion beam is only needed for machining SAM material selectively, since ultra thin SAM is very sensitive to $Ga^+$ ion beam irradiation. Also, minimized beam spot radius (sub-tens nanometer) can be applied to FIB processing. With the ultimate goal of optimizing nano-scale pattern fabrication process, interaction between SAM coated specimen and $Ga^+$ ion dose during FIB processing was observed. From the experimental results, adequate ion dose for machining SAM material was identified.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.19-24
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• 2012

We demonstrate the desert beetle back mimicking hybrid superhydrophilic/superhydrophobic patterned surface by using the combination method of colloidal lithography and gravure offset printing for nano and micro patterning, respectively. The two methods are cost-effective and industrially available techniques compared to the other nano/micro patterning methods. To verify the water collecting function of the hybrid surface, the water condensation behavior is investigated on the chilled surface in ambient temperature and high humidity. Due to the synergetic effect of drop and film wise condensation, the hybrid superhydrophobic/superhydrophilic surface shows the higher efficiency than one of single wettability surfaces. The work is underway to get the good patterns of hybrid surfaces for water collecting from the dew or fog.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.638-643
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• 2013

Laser beam machining (LBM) is fast, contactless and able to machine various materials. So it is used to cut metal, drill holes, weld or pattern the imprinted surface. However, after LBM, there still leave burrs and recast layers around the machined area. In order to remove these unwanted parts, LBM process often uses electrochemical etching (ECE). But, the total thickness of workpiece is reduced because the etching process removes not only burrs and recast layers, but also the entire surface. In this paper, surface coating was performed using enamel after LBM on metal. The recast layer can be selectively removed without decreasing total thickness. Comparing with LBM process only, the surface quality of enamel coating process was better than that. And edge shape was also maintained after ECE.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.989-992
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• 2008

X-ray lithography is one of the most powerful processes in the fabrication of nano/micro structures with a high aspect ratio. This process enables the fabrication of ultra-thin barrier ribs for PDP using X-ray sensitive paste. In this paper, organic material including photo-monomers, photo-oligomers, binder polymer and additives as well as inorganic powders with different size were optimized to fabricate high aspect ratio barrier rib pattern for PDP.

• Journal of the Korean Society of Visualization
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• v.9 no.1
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• pp.17-19
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• 2011

The bubble oscillations play an important role in ultrasonic cleaning processes. In the ultrasonic cleaning of semiconductor wafers, the cleaning process often damages micro/nano scale patterns while removing contaminant particles. However, the understanding of how patterns in semiconductor wafers are damaged during ultrasonic cleaning is far from complete yet. Here, we report the observations of the motion of bubbles that induce solid wall damage under 26 kHz continuous ultrasonic waves. We classified the motions into the four types, i.e. volume motion, shape motion, splitting or jetting motion and chaotic motion. Our experimental results show that bubble oscillations get unstable and nonlinear as the ultrasonic amplitude increases, which may exert a large stress on a solid surface raising the possibility of damaging microstructures.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.15.1-15.1
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• 2009

Nano transfer printing and micro contact printing is well known printing method based on soft lithography which uses conformal soft elastomer with designed surface relief structures. Here I introduce another class of novel 3D nanofabrication technique by using the same elastomer but in a different manner. The approach, which we refer to as proximity field nanopatterning, uses the surface-reliefed elastomers as phase masks to pattern thick layers of transparent, photosensitive materials. Aspects of the optics, the materials, and the physical chemistry associated with this method are outlined. A range of 3D structures illustrate its capabilities, and several application examples demonstrate possible areas of use in technologies ranging from microfluidics to photonic materials to density gradient structures for chemical release and high-energy density science.