• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.727-730
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• 2003

Thin tin oxide film with nano-size particle was prepared on silicon substrate by hydrothermal synthetic method and successive sol-gel spin coating method. The fabrication method of tin oxide film with ultrafine nano-size crystalline structure was tried to be applied to fabrication of micro gas sensor array on silicon substrate. The tin oxide film on silicon substrate was well patterned by chemical etching upto 5${\mu}{\textrm}{m}$width and showed very uniform flatness. The tin oxide film preparation method and patterning method were successfully applied to newly proposed 2-dimensional micro sensor fabrication.

• The KSFM Journal of Fluid Machinery
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• v.9 no.2 s.35
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• pp.19-24
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• 2006

Nano fountain-pen is a novel device to make the constant patterning in micro process using new designed probe. Fountain-pen nanolithography (FPN) is applied for constant supply of liquid in conjunction of patterns and surface variation in the micro process. In this study, nuo fountain-pen is composed with reservoir, micro channels, tip and scondary chamber. Instead of traditional method only using capillary force, liquid can be definitely and exactly injected with membrane pumping by the repulse force of tip. It is dfficult to perform experiments in the micro range so that we carried out a numerical analysis for internal flow, using a commercial code, FlUENT, The velocity, pressure and flow rate are obtained under laminar, unsteady, three-dimensional incompressible flow with no-slip condition, and results are graphically described.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.395-400
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• 2005

Nano-scale fabrication of silicon substrate based on the use of atomic force microscopy (AFM) was demonstrated. A specially designed cantilever with diamond tip, allowing the formation of damaged layer on silicon substrate by a simple scratching process, has been applied instead of conventional silicon cantilever for scanning. A thin damaged layer forms in the substrate at the diamond tip-sample junction along scanning path of the tip. The damaged layer withstands against wet chemical etching in aqueous KOH solution. Diamond tip acts as a patterning tool like mask film for lithography process. Hence these sequential processes, called tribo-nanolithography, TNL, can fabricate 2D or 3D micro structures in nanometer range. This study demonstrates the novel fabrication processes of the micro cantilever and diamond tip as a tool for TNL using micro-patterning, wet chemical etching and CVD. The developed TNL tools show outstanding machinability against single crystal silicon wafer. Hence, they are expected to have a possibility for industrial applications as a micro-to-nano machining tool.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.39-46
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• 2006

Nano-scale fabrication of silicon substrate based on the use of atomic force microscopy (AFM) was demonstrated. A specially designed cantilever with diamond tip, allowing the formation of damaged layer on silicon substrate by a simple scratching process, has been applied instead of conventional silicon cantilever for scanning. A thin mask layer forms in the substrate at the diamond tip-sample junction along scanning path of the tip. The mask layer withstands against wet chemical etching in aqueous KOH solution. Diamond tip acts as a patterning tool like mask film for lithography process. Hence these sequential processes, called tribo-nanolithography, TNL, can fabricate 2D or 3D micro structures in nanometer range. This study demonstrates the novel fabrication processes of the micro cantilever and diamond tip as a tool for TNL using micro-patterning, wet chemical etching and CVD. The developed TNL tools show outstanding machinability against single crystal silicon wafer. Hence, they are expected to have a possibility for industrial applications as a micro-to-nano machining tool.

• Journal of Powder Materials
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• v.20 no.2
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• pp.120-124
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• 2013

This study is carried out to develop the new process for the fabrication of ultra-fine electrodes on the flexible substrates using superhydrophobic effect. A facile method was developed to form the ultra-fine trenches on the flexible substrates treated by plasma etching and to print the fine metal electrodes using conductive nano-ink. Various plasma etching conditions were investigated for the hydrophobic surface treatment of flexible polyimide (PI) films. The micro-trench on the hydrophobic PI film fabricated under optimized conditions was obtained by mechanical scratching, which gave the hydrophilic property only to the trench area. Finally, the patterning by selective deposition of ink materials was performed using the conductive silver nano-ink. The interface between the conductive nanoparticles and the flexible substrates were characterized by scanning electron microscope. The increase of the sintering temperature and metal concentration of ink caused the reduction of electrical resistance. The sintering temperature lower than $200^{\circ}C$ resulted in good interfacial bonding between Ag electrode and PI film substrate.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1806-1809
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• 2008

Study that form micro pattern by direct ink jet printing method is getting attention recently. Direct ink jet printing spout fine droplet including nano metal particle by force or air pressure. There is reason which ink jet printing method is profitable especially in a various micro-patterning technology. It can embody patterns directly without complex process such as mask manufacture or screen-printing for existent lithography. In this study, research of a technology that ejects fine droplet form of Pico liter and forms metal micro pattern was carried with inkjet head of piezoelectricity drive system. Droplet established pattern while ejecting consecutively and move on the surface at the fixed speed. Patterns formed in ink are mixed with organic solvent and polymer that act as binder. So added thermal hardening process after evaporate organic solvent at isothermal after printing. I executed high frequency special quality estimation of CPW transmission line to confirm electrical property of manufactured circuit board. We tried a large area printing to confirm application possibility of an ink jet technology.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.913-918
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• 2005

It is expected that the inkjet technology offers prospect for reliable and low cost manufacturing of FPD (Flat Panel Display). This inkjet technology also offers a more simplified manufacturing process for various part of the FPD than conventional process. For example, recently the novel manufacturing processes of color filter (C/F) in LCD, or RGB patterning in OLED by inkjet printing method have been developed. This elaborates will be considered as the precious point of manufacturing process for the mass production of enlarged-display panel with a low price. On this point of view, we would like to review the status of inkjet technology in FPD, with some results on forming micro line by inkjet patterning of suspension type silver nano ink as below. We have studied the inkjet patterning of synthesized aqueous silver nano-sol on interface-controlled ITO glass substrate. Furthermore, we designed the conductive ink for direct inkjet patterning on bare ITO glass substrate. The first, the highly concentrated polymeric dispersant-assisted silver nano sol was prepared. The high concentration of batch-synthesized silver nano sol was possible to 40 wt%. At the same time the particle size of silver nanoparticles was below $10{\sim}20nm$. The second, the synthesized silver nano sol was inkjet - patterned on ITO glass substrate. The connectivity and width of fine line depended largely on the wettability of silver nano sol on ITO glass substrate, which was controlled by surfactant. The relationship was understood by wetting angle. The line of silver electrode as fine as $50{\sim}100\;{\mu}m$ was successfully formed on ITO glass substrate. The last, the direct inkjet-patternable silver nano sol on bare ITO glass substrate was designed also.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.272-273
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• 2013

Some living thingsuse micro- or nano- structures for living in nature. Scientists and engineers made efforts to mimic them, and they succeeded in making new types of applications. They used 'Namib desert beetle' to self-filling device by moisture harvesting and 'lotus leaf' to self-cleaning device by water repelling. 'Namib desert beetle' and lotus leaf have micro-patterns on their surface, which consists of hydrophobic or hydrophilic materials [1]. Moreover, micro-patterns on the surface make self-filling or self-cleaning property enhanced because of the surface roughness. Surface roughness enhances wettability [2]. Micro-pattern is a significant factor to make the surface be functional, so we want to make new types of functional surface by micro-patterning. In this work,we make several functional micro-patterns (radial, line, and dot arrays) using maskless lithography and analyze the characteristics of each micro-pattern. In order to analyze and understand surface characteristics, micro-patterns with varying sizes are investigated. All experiments are proceeded on mr-DWL5 photo resists coated on silicon wafers in same condition. All the experiments have demonstrated good performances about hydrophobic or hydrophilic property corresponding to their material and structural combinations. In radial micro-pattern, although the surface is flat, water drops on hydrophilic radial pattern can be convergent to a middle point and water drops on hydrophobic radial pattern can be divergent from the middle point. In line array micro-pattern, water drops can roll off along only one direction in parallel with the line arrays. Such phenomena might be mainly caused by the local change of surface roughness. From these results, controlling the movement and direction of water drops is made feasible without introducing a slope, which can potentially be used for new types of applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1118-1121
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• 2009

We have fabricated inverted staggered pentacene Thin Film Transistor (TFT) with 1-${\mu}m$ channel length by micro contact printing (${\mu}$-CP) method. Patterning of micro-scale source/drain electrodes without etching was successfully achieved using silver nano particle ink, Polydimethylsiloxane (PDMS) stamp and FC-150 flip chip aligner-bonder. Sheet resistance of the printed Ag nano particle films were effectively reduced by two step annealing at $180^{\circ}C$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.922-929
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• 2006

In this study, flow characteristics of the FPN (Fountain Pen Nano-Lithography) using active membrane pumping are investigated. This FPN has integrated chamber, micro channel, and high capacity reservoir for continuous ink feed. The most important aspect in this probe provided control of fluid injection using active membrane pumping in chamber. The flow rates in channel by capillary force are theoretically analyzed, including the control of mass flow rates by deflection of membrane. The above results are compared with numerical simulations that calculated by commercial code, FLUENT. The velocity of fluid in micro channel shows linear behaviors. And the mass flows are proportional to the second order function of pumping pressure that is imposed to membrane.