• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.274-279
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• 2007

This study focuses on the enhancement of maskless photolithography as well as the peptide synthesis application with single crystalline silicon micromirrors. A single crystalline silicon micromirror array has been designed and fabricated in order to improve its application to the peptide synthesis. A micromirror rotates about ${\pm}\;9^{\circ}$ at the pull-in voltage, which can range from 90.7 V to 115.1 V. A $210\;{\mu}m-by-210\;{\mu}m$ micromirror device with $270\;{\mu}m$ mirror pitch meets the requirements of an adequately precise separation for peptide synthesis. Synthetic 16 by 16 peptide array corresponds to the same number of micromirrors. The large size of peptide pattern and the separation facilitate biochip experiments using fluorescence assay. The peptide pattern has been synthesized on the GPTS-PEG200 surface with BSA-blocking and thereupon the background was acetylated to reject non-specific bindings. Hence, an averaged slope at the pattern edge has been distinguishably improved in comparison to patterning results from an aluminum micromirror.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.12
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• pp.177-184
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• 2001

C3M(chemical mechanical micro machining) is applied for diminishing the size of burr and fabricating the massless patterning for aluminium wafer(thickness of 1${\mu}m$). It is difficult to perform the micro size machining with the radically increased shear stress. While the miniaturization and function-orientation of parts has been needed in the many field such as electronics, optics and medicine. etc., it is not enough to satisfy the industry needs in the machining technology. In this paper feasibility test of diminishing burr and fabricating maskless pattern was experimented and analyzed. In the experiment oxide layer was farmed on the aluminium with chemical reaction by ${HNO_3}$(10wt%), then the surface was grooved with tungsten carbide tool for the different condition such as the load and fred rate. The result was compared with the conventional machining to show the improvement of C3M with SEM for burr diminish and XPS for atomic existence, AFM for more precise image.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.143-145
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• 1996

A new method of fabricating 3-dimensional patterns on single crystal silicon is presented in this paper. The method utlizes both chemical and mechanical reactions to make patterns with dimensions of few microns in width and submicron in height. The primaryadvantage ofthis new method over conventional methods of making patterns on silicon lies in its cost effectiveness and speed. The process introduced in this paper is a maskless process and does not reauire expensive capital investment. It is expected that this method can be employed for flexible and cost effective fabrication of micro-machine components in MEMS application.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.631-631
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• 2013

Battery has major drawbacks including its size and life expectancy, and environmental problem. As an alternative, energy harvesting is emerging as a potential solution to replace battery along with more energy-efficient IT devices. The idea of harnessing energy from our living environment is sustainable, semi-permanent, and eco-friendly. Also, unlike battery, energy harvester does not require much space to store energy. Therefore, energy harvesting can provide a better source of power for small, portable, and wireless devices. Among various ways of harvesting energy from our surroundings, triboelectricity is chosen due to its potential to be miniaturized, and efficient. Triboelectric effect occurs as two different materials with different polarity of charge separation come into contact through friction, and then become separated so that electric potential difference is achieved. In this research, such characteristic of triboelectricity is used as a way to convert ambient mechanical energy into electric energy.Series of recent researches have shown promising results that the triboelectric energy harvester can be simple and cost effective. However, sufficient electricity level required to operate mobile devices has not yet been achieved.In this research, our group focuses on the design and optimization of triboelectric energy harvesting device to enhance its output. By using maskless lithography to pattern Kapton film and silicon substrate, which is used as a mold for PDMS thin layer, and sputtering metal electrodes on each side, we fabricate and demonstrate different designs of triboelectric energy harvester that utilizes the contact electrification between a polymer thin film and a metal thin foil. In order to achieve optimized result, the output voltage and current are measured under diverse conditions, which include different surface structure and pattern, material, and the gap between layers.

• Laser Solutions
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• v.6 no.1
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• pp.9-16
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• 2003

Micromachining using the DPSS 3rd Harmonic Laser (355nm) has outstanding advantages as a UV source in comparison with Excimer lasers in various aspects such as maintenance cost, maskless machining, high repetition rate and so on. It also has the greater absorptivity of many materials in contrast to other IR sources. In this paper, the process for micro-drilling of blind hole in Cu/PI/Cu substrate with the DPSS UV laser and the scanning device is investigated by the experimental methods. It is known that there is a large gap between the ablation threshold of copper and that of PI. We use the Archimedes spiral path for the blind hole with different energy densities to ablate the different material. Finally, the blind via hole of diameter 100$\mu\textrm{m}$ and 50$\mu\textrm{m}$ was drilled.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.448-451
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• 2003

This study describes a new maskless nano-fabrication technique of Si (100) using the combination of nanometer-scale mechanical forming by nano-indenter XP and KOH wet etching. First the surface of a Si (100) specimen was machined by using the nano-machining system, which utilizes the mechanism of the nano-indenter XP. Next, the specimen was etched by KOH solution. After the etching process, the convex structure or deeper hole is made because of masking or promotion effect of the affected layer generated by nano-machining. On the basis of this interesting fact, some sample structures were fabricated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.177-177
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• 2003

GaN 에피층을 성장에 있어서 가장 문제가 되는 통과 전위를 줄이기 위한 방법 이 여러 가지로 진행되고 있다. 그중에서도 PE(Pendeo Epitaxy) 방법으로 많은 연구가 이루어 졌는데 이경우에 열적인 요인으로 인해 발생하는 스트레스와 마스크 물질로 인하여 그러한 물질들이 서로 반응하거나 성장시 악영향을 끼쳐 결국은 성장되는 GaN층의 결정학적 기울기의 원인이 된다는 것이 밝혀졌다. 따라서 이러한 마스크를 제거하여 PE GaN에서 마스크와 수평으로 자라나는 GaN층사이의 간섭이 사라져서 결정학적 기울기가 감소시킬 수 있게 되었다. 이 연구에서 우리는 위에서 언급했던 마스크를 사용하지 않은 PE GaN의 미세구조적인 특성과 전위들의 거동을 투과전자현미경, 주사 전자현미경 그리고 HRXRD(High Resolution X-Ray diffraction)결과를 이용하여 살펴보았다.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.886-888
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• 1998

By irradiating photoresist on Si or glass with $Ar^+$ (${\lambda}$=514 nm, CW) and Nd:YAG (${\lambda}$=266 and 532nm, pulse) laser beam, the photoresist was etched masklessly in air. Using a fourth harmonic Nd:YAG laser beam, the etching threshold of energy fluence was $25\;J/cm^2$ and the damage of substrate was appeared over $40\;J/cm^2$.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.762-765
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• 2014

We fabricated a periodically poled lithium niobate (PPLN) by direct laser-writing of a quasi-phase-matching (QPM) structure in photolithographic process. Because we do not need to prepare a photomask by electron-beam writing, the "maskless" process shortens the fabrication time and significantly reduces the cost. We evaluated the poling quality of the direct laser-written PPLN by measuring the diffraction noise from the surface relief pattern of the fabricated QPM grating and comparing the results to those from a conventional PPLN made with a photomask. The quality of the PPLN fabricated by direct laser-writing was shown to be equivalent to that fabricated by the conventional method.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.11
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• pp.496-500
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to significantly impact terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (RIE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi-Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7% efficiency of mono-crystalline silicon solar cell and 10.2% multi-crystalline silicon solar cell.