• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.600-602
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• 1995

Using the $O_2$ RIE process, 20{\mu}m$-height polyimide microstructures are fabricated. In LIGA-like process, metal microstructure can be formed by the electroplating using these polyimide microstructures as a plating mould. Reactive ion Etching technique using oxygen gas is used for the patterning of polyimide. The etching rate of the polyimide is increased with increased pressure and RF power. The anisotropic vertical sidewall can be obtained at low pressure, but the etched surface state is not so good yet. "Micrograss", which is formed during the RIE and disturbs uniform electroplating, can be removed effectively by the wet itching of the chromium sacrificial layer. More studies about the improvement of an etched surface state and the removal of microsgrass are needed.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1713-1717
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• 2008

We have developed a nanoparticle focusing mask which can generate particle arrays directly on the large area with high resolution. Using this mask, nanomaterials are precisely deposited onto desired positions on a substrate surface. We obtained various sizes of arrays ranging from 80 nm to 6 ${\mu}m$ with silver and copper nanoparticles that are generated by a spark discharge and an evaporation-condensation method. The feather size is much smaller than that of mask openings due to the focusing effects, like electrostatic lens, caused by charge or electric potential on insulator mask surface, which also prevent a mask clogging. The particle array size depends on the size of mask open patterns and focusing effects near the mask relate to ion flow rate and electric potential. We have demonstrated that diverse size of arrays with high resolution could be obtained repeatedly using the same sized mask in atmosphere.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.869-875
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• 1996

In this article the effects of process parameters of inductively coupled plasma etching with $SF_6$ /$N_2$/Ar mixture gas and mask materials on the etched profile of W were investigated. While the etched profile was improved by $N_2$-addition, low working presure, and reduced $SF_6$ flow rate, the etching selectity (W against SAL resist) was decreased. Due to the difficulty of W etching with single layer resist, sputter deposited $Al_2O_3$ film was used as a hardmask. Reduction of required EB resist thickness through $Al_2O_3$ mask application could reduce proximity effect during e-beam patterning, but the etch anisotropy was degraded by decreased sidewall passiviation effect.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.65-69
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• 2017

This paper presents a Technology-CAD (TCAD) simulation of the characteristics of crystalline Si pillar array solar cells. The junction depth and the surface concentration of the solar cells were optimized to obtain the targeted sheet resistance of the emitter region. The diffusion model was determined by calibrating the emitter doping profile of the microscale silicon pillars. The dimension parameters determining the pillar shape, such as width, height, and spacing were varied within a simulation window from ${\sim}2{\mu}m$ to $5{\mu}m$. The simulation showed that increasing pillar width (or diameter) and spacing resulted in the decrease of current density due to surface area loss, light trapping loss, and high reflectance. Although increasing pillar height might improve the chances of light trapping, the recombination loss due to the increase in the carrier's transfer length canceled out the positive effect to the photo-generation component of the current. The silicon pillars were experimentally formed by photoresist patterning and electroless etching. The laboratory results of a fabricated Si pillar solar cell showed the efficiency and the fill factor to be close to the simulation results.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1122-1124
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• 2009

Organic thin-film transistors (OTFTs) were fabricated by using the transfer patterning method. In order to remove Au pattern easily, UV-curable polymer mold was surface treated. Au source/drain (S/D) pattern was transferred to insulator-coated substrate surface. Fabricated OTFTs were compared to OTFTs using vacuum-deposited Au S/D. Additionally, transistor diodes were characterized.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.142.1-142.1
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• 2013

The patterning and doping technique enables graphene to replace the metal electrode as a charge injection layer in the pentacene based thin film transistor. However, it is known that pentacene molecules form lying-down coordination on the graphene surface. Pentacene thin film showed that the highly occupied molecular orbital is 0.2~0.4 eV lower in the standing up coordination than in the lying down coordination. Here, we report the formation of standing-up coordination and lowered HOMO level of the pentacene layer grown on the graphene layer doped with CYTOP.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.168-168
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• 2009

핸드폰, 노트북과 같이 최신경량 전자재료로 만들어지는 전자제품의 수요가 급증함에 따라 반도체 배선의 폭이 점점 작아지고, 이로 인해 프린팅공정을 이용한 미세 배선기술이 활발히 개발되고 있다. 이에 본 연구는 미세배선에 높은 전기전도도를 부여하기 위하여 전기도금을 실시하였으며, 균일한 도금층을 얻기 위하여 첨가제에 따른 분극거동을 분석하고 이를 바탕으로 양극 및 음극 형상에 따른 구리의 성장 거동을 시뮬레이션을 통하여 분석하였다. 균일한 증착을 위해서는 첨가제의 역할도 중요하지만 양극과 음극의 형상에 따라서도 구리성장 거동에 영향을 미치는 것을 알 수 있었다.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.362-367
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• 2014

We report the design, fabrication of a $Si_3N_4$ probe and calculation of its mechanical properties for DPN(dip pen nanolithography), which consists of dual tips. Concept of dual tip probe is to employ individual tips on probe as either an AFM tip for imaging or a writing tip for nano patterning. For this, the dual tip probe is fabricated using low residual stress $Si_3N_4$ material with LPCVD deposition and MEMS fabrication process. On the basis of FEM analysis we show that the functionality of dual tip probe for imaging is dependent on the dimensions of dual tip probe, and high ratio of widths of beam areas is preferred to minimize curvature variation on probe.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.75-80
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• 2016

Ink-jet printing has become a widespread technology with the society's increase in aesthetic awareness. Especially, ink-jet printing using glazed ceramic ink can offer huge advantages including high quality decoration, continuous processing, glaze patterning, and direct reproduction of high resolution images. Recently, ceramic ink-jet printing has been rapidly introduced to decorate the porcelain product and the ceramic tiles. In this study, we provide an effective method to apply ceramic ink-jet decorations on the glass substrates using a oleophobic coating with perfluorooctyl trichlorosilane. The ink-jet printed patterns were much clearer on the oleophobically coated glass surface than the bare glass surface. The contact angle of the ceramic ink was maximized to the value of $64.0^{\circ}$ on the glass surface, when it was treated with 1 vol% PFTS solution for 1 min. The effects of the printing conditions and firing process on the ink-jet printed patterns on the oleophobically coated glass were also investigated.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.25-29
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• 2008

We introduce a new fabrication process for antireflective structured surfaces. A 4-inch silicon wafer was dipped in a suspension of 300-nm-diameter silica particles dispersed in a toluene solution. When the wafer was drawn out of the suspension, a hexagonally packed monolayer structure of particles self-assembled on almost the complete wafer surface. Due to the simple process, this could be applied to micro- and nano-patterning. The self-assembled silica particles worked as a mask for the subsequent reactive ion etching. An array of nanometer-sized pits could be fabricated since the regions that correspond to the small gaps between particles were selectively etched off. As etching progressed, the pits became deeper and combined with neighboring pits due to side-etching to produce an array of cone-like structures. We investigated the effect of etching conditions on antireflection properties, and the optimum shape was a nano-cone with height and spacing of 500 nm and 300 nm, respectively. This nano-structured surface was prepared on a $30\;{\times}\;10-mm$ area. The reflectivity of the surface was reduced 97% for wavelengths in the range 400-700 nm.