• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.1
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• pp.23-30
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• 2021

Purpose: The aim of this study was to investigate effect of zirconia on osseointegration and Surface appearance by surface treatments using various acid solution. Materials and Methods: The prepared zirconia disks were treated with hydrofluoric acid solution and photo-assisted etching under various condition. The surface was analyzed by SEM and the surface roughness was analyzed by using surface profiler. The osteogenic effect of MC3T3-E1 cells was assessed via fluorescent staining observation and reverse transcriptase-polymerase chain reaction (RT-PCR). Results: Various roughness were obtained according to the surface treatment method. The surface roughness increased in the group treated with hydrofluoric acid solution, but that had week network structure. In the method using photo-assisted etching, the surface roughness increased in micro units. Cell reaction showed better results in the photo-assisted etching group than in the hydrofluoric acid-treated group (P < 0.05). And it showed even osteoblastic cell distribution in photo-assisted etching group. Conclusion: As a result, the photo-assisted etching method is more effective than the simple acid solution treatment for zirconia treatment for osseointegration.

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.57-62
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• 2022

The plasma resistance of multi-component glasses containing La, Gd, Ti, Zn, Y, Zr, Nb, and Ta was analyzed in this study. The plasma etching was performed via inductively coupled plasma-reactive ion etching (ICP-RIE) using CF₄/O₂/Ar mixed gas. After the reaction, the glass with a low fluoride sublimation temperature and high content of P, Si, and Ti elements showed a high etching rate. On the other hand, the glass containing a high fluoride sublimation temperature component such as Ca, La, Gd, Y, and Zr exhibited high plasma resistance because the etch rate was lower than that of sapphire. Glass with low plasma resistance increased surface roughness after etching or nanoholes were formed on the surface, but glass with high plasma resistance showed little change in surface microstructure. Thus, the results of this study demonstrate the potential for the development of plasma-resistant glasses (PRGs) with other compositions besides alumino-silicate glasses, which are conventionally referred to as plasma-resistant glasses.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.291-291
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• 2013

The wettability of TiO2 layers is controlled by forming highly ordered arrays of nanocones using nanopatterning, based on self-assembly and dry etching. Nanopatterning of TiO2 layers is achieved via formation of self-assembled monolayers of SiO2 spheres fabricated using the Langmuir-Blodgett technique, followed by dry etching. Compared to a thin film TiO2 layer, the nanopatterned TiO2 samples show a smaller static water contact angle, where the water contact angle decreases as the etching time increases, which is attributed to the Wenzel equation. When TiO2 layers are coated by 1H,1H,2H,2H-perfluorooctyltrichlorosilane, we observed the opposite behavior, exhibiting superhydrophobicity (up to contact angle of $155^{\circ}$) on the nanopatterned TiO2 layers. Self-assembled nanopatterning of the TiO2 layer may provide an advanced method for producing multifunctional transparent layers with self-cleaning properties.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3451-3455
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• 2013

Single-crystalline silicon nanowires (SiNWs) were fabricated by using an electroless metal-assisted etching of bulk silicon wafers with silver nanoparticles obtained by wet electroless deposition. The etching of SiNWs is based on sequential treatment in aqueous solutions of silver nitrate followed by hydrofluoric acid and hydrogen peroxide. SEM observation shows that well-aligned nanowire arrays perpendicular to the surface of the Si substrate were produced. Free-standing SiNWs were then obtained using ultrasono-method in toluene. Alkyl-derivatized SiNWs were prepared to prevent the aggregation of SiNWs and obtained from the reaction of SiNWs and dodecene via hydrosilylation. Optical characterizations of SiNWs were achieved by FT-IR spectroscopy and indicated that the surface of SiNWs is terminated with hydrogen for fresh SiNWs and with dodecyl group for dodecyl-derivatized SiNWs, respectively. The main structures of dodecyl-derivatized SiNWs are wires and rods and their thicknesses of rods and wire are typically 150-250 and 10-20 nm, respectively. The morphology and chemical state of dodecyl-derivatized SiNWs are characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.41-45
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• 1984

The production of high-quality epitaxial layers almost always involves an etching step of silicon substrates with HCl gas prior to epitaxy, In this work, an investigation has been made on the etch rate and the etch-pit formation as a function of HCl gas concentration and etch temperature at atmospheric pressure (1 atm.) and reduced pressure (0.1 atom.). As a result, it is found that the etch rate is proportional to the square of the HCI gas concentration (XHC12) and the apparent ativation energy is between 0 and 111 Kcal/mole for both ammospheric and reduced pressure operation. From these results, it is expected that the HCI etching of silicon in reduced pressure operation proceeds, as in atmospheric operation, via the reaction ; Si + 2HCl ↔ SiCl2 + H2.

• Journal of the Korean institute of surface engineering
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• v.50 no.5
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• pp.315-321
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• 2017

Antireflective pyramid arrays can be readily obtained via anisotropic etching in alkaline solution (KOH, NaOH), which is widely used in crystalline-Si (c-Si) solar cells. The periodic inverted pyramid arrays show even lower light reflectivity because of their superior light-trapping characteristics. Since this inverted pyramidal structures are mostly achieved using very complex techniques such as photolithograpy and laser processes requiring extra costs, here, we demonstrate the Cu-nanoparticle assisted chemical etching processes to make the inverted pyramidal arrays without the need of photolithography. We have mainly controlled the concentration of $Cu(NO_3)_2$, HF, $H_2O_2$ and temperature as well as time factors that affecting the reaction. Optimal inverted pyramid structure was obtained through reaction parameters control. The reflectance of inverted pyramid arrays showed < 10% over 400 to 1100 nm wavelength range while showing 15~20% in random pyramid arrays.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.90.2-90.2
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• 2013

Vertically-aligned silicon nanostructure arrays (SNAs) have been drawing much attention due to their useful electrical properties, large surface area, and quantum confinement effect. SNAs are typically fabricated by chemical vapor deposition, reactive ion etching, or wet chemical etching. Recently, metal-assisted chemical etching process, which is relatively simple and cost-effective, in combination with nanosphere lithography was recently demonstrated for vertical SNA fabrication with controlled SNA diameters, lengths, and densities. However, this method exhibits limitations in terms of large-area preparation of unperiodic nanostructures and SNA geometry tuning independent of inter-structure separation. In this work, we introduced the layerby- layer deposition of polyelectrolytes for holding uniformly dispersed polystyrene beads as mask and demonstrated the fabrication of well-dispersed vertical SNAs with controlled geometric parameters on large substrates. Additionally, we present a new means of building in vitro neuronal networks using vertical nanowire arrays. Primary culture of rat hippocampal neurons were deposited on the bare and conducting polymer-coated SNAs and maintained for several weeks while their viability remains for several weeks. Combined with the recently-developed transfection method via nanowire internalization, the patterned vertical nanostructures will contribute to understanding how synaptic connectivity and site-specific perturbation will affect global neuronal network function in an extant in vitro neuronal circuit.

• Journal of the Semiconductor & Display Technology
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• v.18 no.4
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• pp.96-99
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• 2019

Atomic layer etching (ALE) is one of the most promising techniques in the semiconductor industry. Since ALE has to be precisely controlled on the angstrom scale to achieve ideal results, an in-situ analysis of the processes is highly required. In this regard, we found during ALE experiments with in-situ monitoring with an ellipsometer that changes in the substrate temperature affected the refractive index of a material, leading to changes in measured film thickness. In addition, more ideal ALE results could be achieved by keeping the substrate temperature constant.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.141-141
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• 2012

고종횡비 10:1 비아를 Si wafer 상에 형성하기 위해 $7{\mu}m$ 직경의 마스크로 포토작업하여 Cr층을 100nm 스퍼터링하여 PR(photo resistor) 대신의 에칭 barrier 막으로 사용하였다. 얼라인, 노광, 현상을 거쳐 Cr에칭, PR 제거후 ICP(inductively coupled plasma) 공정으로 Si deep etching하여 via 직경 $10.16{\mu}m$, 깊이 $102.5{\mu}m$의 고종횡비 비아를 형성하였다. 구리필링도금을 위해서 필수적인 seed layer는 단층 또는 다층의 금속막을 스퍼터링 법으로 형성하였다. 형성된 seed layer 단면을 FE-SEM(Field emission scanning electron microscope)으로 관찰하여 내부에 seed 층의 형성 유무를 확인하였다.

• 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.