• Journal of the Korean institute of surface engineering
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• v.47 no.3
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• pp.128-136
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• 2014

In the present study, we successfully developed an eco-friendly chemical etching solution and proper condition for plating on ABS material. The mechanism of forming Ni plating layer on ABS substrate is known as following. In general, the etching solution used for the etching process is a solution of chromic acid and sulfuric acid. The etching solution is given to the surface resulting in elution of butadiene group, so-called anchor effect. Such a rough surface can easily adsorb catalyst resulting in the increase of adhesion between ABS substrate and Ni plating layer. However a use of chromic acid is harmful to environment. It is, therefore, essential to develop a new alternative solution. In the present study, we proposed an eco-friendly etching solution composed of potassium permanganate, sulfuric acid and phosphoric acid. This solution was testified to observe the surface microstructure and the pore size of electrical Ni plating layer, and the adhesive correlation between deposited layers fabricated by electro Ni plating was confirmed. The result of the present study, the newly developed, eco-friendly etching solution, which is a mixture of potassium permanganate 25 g/L, sulfuric acid 650ml/L and phosphoric acid 250ml/L, has a similar etching effect and adhesion property, compared with the commercially used chromium acid solution in the condition at $70^{\circ}C$ for 5 min.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.72-73
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• 2012

Metal line을 형성하는 방법에는 그라비아 인쇄, 잉크젯 인쇄, photo 공정 후 박막 증착 공정 등을 많이 사용한다. 본 연구에서는 Micro-imprinting 공정과 DFR photo lithography 공정을 통해 음각의 미세한 pattern을 형성한 후 sputtering과 printing을 이용하여 pattern의 filling을 통해 metal line을 구현하는 것을 목표로 하였다. Pattern을 형성한 후 RIE 공정을 통해 기판 표면의 친수성 처리를 하고, SAM 공정을 통해 코팅 막의 소수성 처리를 하였다. Sputtering과 전면 프린팅 및 건조 후 strip 공정을 통해 metal line을 형성하고, 이에 대한 표면 특성과 전기적 특성을 분석하였다.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.69-76
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• 1982

The purpose of this study was to evaluate the color penetration of cavity margin with composite resin restorations in some Korean foods substance-soy sauce and hot bean paste. Fifty specimans which were extracted caries free third molar of young adults recently. All of the prepared 100 cavities were filled with two kinds of composite resin (Hipol$^{(R)}$and Restodent$^{(R)}$). The experimental specimans were divided into five groups by the following procedures. Group I : Filling of composite resin and polishing. Group II : Filling, polishing, etching of cavity and sealing. Group III : Etching, sealing, filling and polishing. Group IV : Etching, sealing, filling, polishing, and repeated of etching of cavity margin and sealing. Group V : Etching, sealing, filling, polishing, and sealing again without etching. Before examination, the restorated teeth were subjected to thermal cycling ($4^{\circ}C$ and $60^{\circ}C$). All the specimens were immersed in soy and 30% hot bean paste solution under $37^{\circ}C$ incubator during six weeks. Then, the specimens were sectioned bucco-lingually through the center of two restorations with diamond disk and examined under a. metallographic microscope. (Union 6617 U.S.A.) Thereafter, the degree of color penetration was calculated and analyzed. The obtained results were as follows: 1. The color penetration was the lowest in the procedure of Group III which was acid etching, sealing, composite resing filling, and polishing. 2. The color penetration occured in soy and hot bean paste, but the degree of penetration was not so significant statistically between them. 3. The degree of color penetration was not so significant statistically between Hipol$^{(R)}$ and Restondent$^{(R)}$.

• Journal of Integrative Natural Science
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• v.6 no.3
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• pp.170-175
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• 2013

Silicon nanowires were detached and obtained from silicon nanowire arrays on silicon substrate using a ultrasono-method. Silicon nanowire arrays on silicon substrate were prepared with an electroless metal assisted etching of p-type silicon. The etching solution was an aqueous HF solution containing silver nitrate. SEM observation shows that well-aligned nanowire arrays perpendicular to the surface of the silicon substrate were produced. After sonication of silicon nanowire array, an individual silicon nanowire was confirmed by FESEM. Optical characteristics of SiNWs were measured by FT-IR spectroscopy. The surface of SiNWs are terminated with hydrogen.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.45-50
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• 2022

The etching with high selectivity of silicon dioxide over silicon nitride is essential in semiconductor fabrication, and gas phase etch (GPE) can increase the competitiveness of the selective dielectric etch. In this work, GPE of plasma enhanced chemical vapor deposited SiO₂ was performed, and the effects of process parameters, such as temperature, partial pressure ratio, and gas supply cycle, are investigated in terms of etch rate and within wafer uniformity. Employing multiple regression analysis, the importance of each parameter elements is analyzed.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.514-521
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• 2009

The aim of this study was to evaluate the bonding ability of two self etch systems to human primary and permanent enamel and the effect of additional acid etching time. Exfoliated, caries free human primary molar(n=65) and permanent molar extracted (n=65) were used. prepared enamel specimens were randomly divided into 2 test groups and a control group. The control group(n=10) were treated with 35% phosphoric acid gel and Scotchbond Multi-purpose adhesive. Experimental groups(self-etching systems) were subdivided into 6 groups(each n=10) according to additional etching time(0s, 5s, 10s, 15s, 20s, 30s). The result were as follows : 1) The shear bond strengths of the self-etching adhesives(Clearfil SE Bond, Adper Prompt L-pop) without additional etching were lower than control group(Scotch Bond Multipurpose). 2) Between the same self-etch adhesive groups, additional etched groups showed higher shear bond strength 3) There was no significant difference between primary and permanent enamel. In conclusion, bond strength of self-etch adhesives to enamel could be increased with additional etching.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.12-16
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• 2001

We investigated the etching characteristics of $YMnO_3$ thin films in high-density plasma etching system. In this study. $YMnO_3$ thin films were etched with $CF_{4}/Ar$ gas chemistries in inductively coupled plasma (ICP). Etch rates of $YMnO_3$ were measured according to gas mixing ratios. The maximum etch rate of $YMnO_3$ is 18 nm/min at $CF_{4}/(CF_{4}+Ar)$ of 20%. In optical emission spectroscopy (OES) analysis, F radical and Ar* ions in plasma at various gas chemistries decreased with increasing $CF_4$ content. Chemical states of $YMnO_3$ films exposed in plasma were investigated with x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). There is a chemical reaction between metal (Y, Mn) and F and metal-fluorides were removed effectively by Ar ion sputtering. $YF_x$, $MnF_x$ such as YF, $YF_2$, $YF_3$ and $MnF_3$ Were detected using SIMS analysis. The etch slope is about $65^{\circ}C$ and free of residues.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.75-79
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• 2003

We studied InP etch results in high density planar inductively coupled $BCl_3$ and $BCl_3$/Ar plasmas. The investigated process parameters were ICP source power, RIE chuck power, chamber pressure and $BCl_3$/Ar gas composition. It was found that increase of ICP source power and RIE chuck power raised etch rate of InP, while that of chamber pressure decreased etch rate. Etched InP surface was clean and smooth (RMS roughness < 2 nm) with a moderate etch rate ($300\;{\sim}\;500\;{\AA}/min$) after the planar $BCl_3/Ar$ ICP etching. It may make it possible to open a new regime of InP etching with $CH_4/H_2$ - free plasma chemistry. Some amount of Ar addition (< 50%) also improved etch rates of InP, while too much Ar addition reduced etch rates of InP.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.149-158
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• 2002

Recently, the minimum line width shows a tendency to decrease and the multi-level increases in semiconductor. Therefore, a planarization technique is needed and chemical mechanical polishing(CMP) is considered as one of the most suitable process. CMP accomplishes a high polishing performance and a global planarization of high quality. However there are several defects in CMF, such as micro-scratches, abrasive contaminations and non-uniformity of polished wafer edges. Wet etching process including spin-etching can eliminate the defects of CMP. It uses abrasive-free chemical solution instead of slurry. On this study, ILD(Interlayer-Dielectric) was removed by CMP and wet etching process using DHF(Diluted HF) in order to investigate the possibility of planrization by wet etching mechanism. In the thin film wafer, the results were evaluated from the viewpoint of material removal rate(MRR) and within wafer non-uniformity(WIWNU). And the pattern step heights were also compared for the purpose of planarity characterization of the patterned wafer. Moreover, Chemical polishing process which is the wet etching process with mechanical energy was introduced and evaluated for examining the characteristics of planarization.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.391-392
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• 2012

In these days, the desire for the precise and tiny displays in mobile application has been increased strongly. Currently, laser displays ranging from large-size laser TV to mobile projectors, are commercially available or due to appear on the market [1]. In order to achieve a mobile projectors, the semiconductor laser diodes should be used as a laser source due to their size and weight. In this presentation, the continuous etch characteristics of Pd and AlGaN/GaN superlattice for the fabrication of blue laser diodes were investigated by using inductively coupled $CHF_3$ and $Cl_2$ -based plasma. The GaN laser diode samples were grown on the sapphire (0001) substrate using a metal organic chemical vapor deposition system. A Si-doped GaN layer was grown on the substrate, followed by growth of LD structures, including the active layers of InGaN/GaN quantum well and barriers layer, as shown in other literature [2], and the palladium was used as a p-type ohmic contact metal. The etch rate of AlGaN/GaN superlattice (2.5/2.5 nm for 100 periods) and n-GaN by using $Cl_2$ (90%)/Ar (10%) and $Cl_2$ (50%)/$CHF_3$ (50%) plasma chemistry, respectively. While when the $Cl_2$/Ar plasma were used, the etch rate of AlGaN/GaN superlattice shows a similar etch rate as that of n-GaN, the $Cl_2/CHF_3$ plasma shows decreased etch rate, compared with that of $Cl_2$/Ar plasma, especially for AlGaN/GaN superlattice. Furthermore, it was also found that the Pd which is deposited on top of the superlattice couldn't be etched with $Cl_2$/Ar plasma. It was indicating that the etching step should be separated into 2 steps for the Pd etching and the superlattice etching, respectively. The etched surface of stacked Pd/superlattice as a result of 2-step etching process including Pd etching ($Cl_2/CHF_3$) and SLs ($Cl_2$/Ar) etching, respectively. EDX results shows that the etched surface is a GaN waveguide free from the Al, indicating the SLs were fully removed by etching. Furthermore, the optical and electrical properties will be also investigated in this presentation. In summary, Pd/AlGaN/GaN SLs were successfully etched exploiting noble 2-step etching processes.