• Transactions of Materials Processing
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• v.18 no.3
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• pp.268-273
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• 2009

Ultraviolet nanoimprint lithography (UV-NIL), which is performed at a low pressure and at room temperature, is known as a low cost method for the fabrication of nano-scale patterns. In the patterning process, maintaining the uniformity of the residual layer is critical as the pattern transfer of features to the substrate must include the timed etch of the residual layer prior to the etching of the transfer layer. In pursuit of a thin and uniform residual layer thickness, the initial volume and the position of each droplet both need to be optimized. However, the monomer mixtures of resin had a tendency to evaporate. The evaporation rate depends on not only time, but also the initial volume of the monomer droplet. In order to decide the initial volume of each droplet, the accurate prediction of evaporation behavior is required. In this study, the theoretical model of the evaporation behavior of resin droplets was developed and compared with the available experimental data in the literature. It is confirmed that the evaporation rate of a droplet is not proportional to the area of its free surface, but to the length of its contact line. Finally, the parameter of the developed theoretical model was calculated by curve fitting to decide the initial volume of resin droplets.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.2
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• pp.132-139
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• 2000

This paper reports a novel micromachining process based on UV-LIGA process and (110) silicon anisotropic etching for fabrication of a high-aspect-ratio comb actuator. The comb electrodes are fabricated by (110) SILICON comb structure considering the etch-rate-ratio between (110) and (111) planes and lateral etch rate of a beam-type structure. The fabricated structure was$ 400\mum \; thick\; and\; 18\mum$ wide comb electrodes separated by $7\mim$ so that the height-gap ratio was about 57. Also considering resonant frequency of the comb actuator and the frequency-matching between sensing and driving mode for gyroscope application, we designed the number, width, height and length of the spring structures. Electroplated gold springs on both sides of the seismic mass were $15\mum\; wide,\; 14\mum\; thick\; and \; 500\mum$ long. The fabricated comb actuator had resonant frequency ay 1430Hz, which was calculated to be 1441Hz. The proposed fabrication process can be applicable to the fabrication of a high-aspect-ratio comb actuator for a large displacement actuator and precision sensors. Moreover, this combined process enables to fabricate a more complex structure which cannot be fabricate only by surface or bulk micromachining.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.199-206
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• 2005

Mask manufacturing is a high COC and COO process in developing of semiconductor devices because of mask production tool with high resolution. Direct writing has been thought to be the one of the patterning method to cope with development or small-lot production of the device. This study consists two categories. One is the additional process of the direct and maskless patterning generation using SLA for easy and convenient application and the other is a removal process using wet-etching process. In this study, cured status of epoxy pattern is most important parameter because of the beer-lambert law according to the diffusion of UV light. In order to improve the contact force between patterns and substrate, prime process was performed and to remove the semi-cured resin which makes a bad effects to the pattern, spin cleaning process using TPM was also performed. At a removal process, contact force between photo-curable resin as an etching mask and Si wafer is important parameter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.129-129
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• 2006

인쇄회로를 제작하기 위하여 기판상에 에칭 레지스트, 도금막, 절연재료, 솔더 마스크 등을 패터닝 하게 되는데, 일반적으로 이러한 유기체 막들은 대부분 액상이나 고형의 필름 형태로 패턴을 형성하게 된다. 형성된 패턴과 동박과의 접착력 향상이 가장 주요한 문제점 중의 하나이다. 상대적으로 편평한 동박면과 유기체 막과의 접착력을 향상시키기 위해 일반적으로 접촉 면적을 증가시키기 위한 표면개질을 하게 된다. 기계적 브러싱이나 스크러빙에 의해서도 기판상의 동박의 surface topography 를 개선하기 위한 노력이 시도 되고 있지만, 본 연구에서는 microetching 방법에 의해서 화학적으로 동박 표면상에 최대한 요철을 많이 형성하여 에칭 레지스트와 동박 간의 접착력을 증대시키기 위한 연구를 수행하였다.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.130-136
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• 2000

Generally, the build-up printed circuit board manufactured by the sequential process with etching, plating, drilling etc. requires many types of equipments and lead time. Etching process is suitable for mass production, however, it is not adequate for manufacturing prototype in the developing stage. In this study, we introduce a screen printing technology to prototyping a build-up printed circuit board. As for the material, photo/thermal curable resin and conductive paste are used for the formation of dielectric and conductor. The build-up structure is made by subsequent processes such as the formation of liquid resin thin layer, the solidification by UV/IR light, and via filling with conductive paste. By use of photo curable resin, productivity is greatly enhanced compared with thermal curable resin. Finally, the basic concept and the possibility of build-up printed circuit board prototyping are proposed in comparison with to the conventional process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.30-35
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• 2013

In order to increase cell efficiency in crystalline silicon solar cell, reduction of light reflection is one of the essential problem. Until now silicon wafer was textured by wet etching process which has random patterns along crystal orientation. In this study, high aspect ratio patterns are manufactured by nano imprint process and reflectance could be minimized under 1%. After that, screen printed solar cell was fabricated on the textured wafer and I-V characteristics was measured by solar simulator. Consequently cell efficiency of solar cell fabricated using the wafer textured by nano imprint process increased 1.15% than reference solar cell textured by wet etching. Internal quantum efficiency was increased in the range of IR wave length but decreased in the UV wavelength. In spite of improved result, optimization between nano imprinted pattern and solar cell process should be followed.

• Journal of Integrative Natural Science
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• v.3 no.1
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• pp.24-27
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• 2010

Multi-functionalized rugate porous silicon (PSi) for biosensor was developed by hydrosilylation with silole and its further reaction with biotin groups. PSi was generated by an electrochemical etching of silicon wafer in aqueous ethanolic HF solution PSi prepared by using etching conditions showed that many sharp spectral lines can be obtained in the optical reflectivity spectrum. 1,1-hydrovinyl-2,3,4,5-tetraphenylsilole was obtained from the reaction of 1,1-dilithio-2,3,4,5-tetraphenyl-1,3-butadiene with dichlorovinylsilane. Multi-functionalized PSi with silole and biotin groups was characterized by UV-vis absorption spectroscopy, Ocean optics 2000 spectrometer, and fluorescence spectroscopy. Optical characteristics such as reflectivity and photoluminescence (PL) were observed. An increase of the reflection wavelength in the reflectivity spectrum by 20 nm was observed, indicative of a change in refractive indices induced by hydrosilylation of the silole and biotin groups to the rugate PSi. This red-shift was attributed to the replacement of some of the Si-H group of fresh rugate PSi with silole and biotin group.

• Journal of Integrative Natural Science
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• v.14 no.4
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• pp.147-154
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• 2021

A luminescent porous silicon sensor, whose surface was passivated with organic molecule via hydrosilylation under various conditions, has been researched to measure the photoluminescence (PL) stability of porous silicon (PSi). Photoluminescent PSi were synthesized by an electrochemical etching of n-type silicon wafer under the illumination with a 300 W tungsten filament bulb during the etching process. The PL of PSi displayed at 650 nm, which is due to the quantum confinement of silicon quantum dots in the PSi. To stabilized the photoluminescence of PSi, the hydrosilylation of PSi with silole molecule containg vinyl group was performed. Surface morphologies of fresh PSi and surface-modified PSi were obtained with a cold FE-SEM. Optical characterization of red photoluminescent silicon quantum dots was investigated by UV-vis and fluorescence spectrometer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.3
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• pp.299-305
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• 1995

Visible photoluminescing (PL) silicon at room temperature has been prepared by a dry technique, that is, by spark processing, contrary to anodically etched porous silicon. PL peak maximum of photoluminescing spark processed Si was shifted to blue 520 nm. The stability of spark processed Si towards degradation upon UV radiation was found to be extremely high. Results from high resolution TEM, XRD and XPS studies suggest that spark processed silicon involves minute nanocrystalline (polycrystalline) particles which are imbedded in an amorphous matrix, preferably $SiO_2$.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1497_1498
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• 2009

This paper presents the simulation of micro-lens arrays based on dry and wet etching technique. Code V (Optical Research Associates Ltd) simulation was performed to extract optimal design parameters of a Micro-Lens Array(MLA). Thickness of UV adhesive, wavelength of laser source, curvature, and shape of lens surface were chosen for the design parameters. The simulation results showed that focal length of a MLA decreased with the increase of UV adhesive thickness. And the focal length depended on shape of lens surface and length of laser source.