• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.118-122
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• 2007

Phase-change wet-etching technology using GeSbTe phase-change films is developed. Selective etching between an amorphous and a crystalline phase can be carried out with an alkaline etchant of NaOH. Etching selectivity is dependent not only on the concentration of the alkaline etchant but also on the film structure. Specifically, metal films for heat control cause marked effects on the etching properties of GeSbTe film. Surviving amorphous pits can be obtained with Al metal layer, however etched amorphous pits are seen with Ag metal layer. An opposite selective etching behavior can be observed between samples with two different metal layers.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.1
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• pp.73-83
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• 1992

Now composite resin restoration is clinically accepted in the repair of fractured PFM case, many mechanical surface treatment methods are performed to increase retentive force. The main purpose of this study was to compare the retentive force among the possible surface treatments and to insure the best method for the clinical application to the fractures porecelain and the exposed metal surface. To compare and to analyze the retentive force of repair resin, porcelain specimen were divided into 2 groups, etching group and non-etching group, and etching group were treated with 37% $H_3PO_4$, 1.23% APF, 10% HF and non-etching groups were treated with diamond bur, micro-sandblasasting. Also, metal specimens were divided by 2 groups : one was non-precious metal group which was treated with diamond bur, micro-sandblasting and tin plating and electrolytic etching, the other was precious metal group which was composed of micro-sandblasting treatment only and tin plating treatment with micro-sandblasting. Each specimen had been restored for 48 hours and the bond strength of each specimen was calculated with Universal testing machine. The results were as follows : 1. Porcelain specimen had higher bonding strength than metal specimen for the repair resin(P<0.01). 2. In porcelain specimen, 10% HF etching group had the highest bonding strength among etching and non-etching group. 3. Metal specimen treated with micro-sandblasting had highest bonding strength among the non-sandblasting had hightest bonding strength among the non-precious group, tin plating group had higher bonding strength than micro-sandblasting group between the precious metal groups. 4. Bonding strength of tin plating was increased in precious metal group only.

• Journal of the Korean Electrochemical Society
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• v.16 no.1
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• pp.1-8
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• 2013

This review article summarizes metal-assisted chemical etching (MAC etch or MACE), an anisotropic etching method for Si, and describes principles, main factors, and recent achievements in literature. In 1990, it was discovered that, with metal catalyst on surface and $H_2O_2$/HF as etchant, Si substrate can be etched anisotropically, in even in solution. In contrast to high-cost vacuum-based dry etching methods, MAC etch enables to fabricate a variety of high aspect ratio nanostructures through wet etching process.

• Journal of the Korean Electrochemical Society
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• v.14 no.4
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• pp.191-195
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• 2011

Wet chemical etching methods were utilized to conduct Si surface texturing, which could enhance photoelectrochemical hydrogen generation rate. Two different etching methods tested, which were anisotropic metal-catalyzed electroless etching and isotropic etching. The Si nano-texture that was fabricated by the anisotropic etching showed ~25% increase in photocurrent for H2 generation. The photocurrent enhancement was attributed to the reduced reflection loss at the nano-textured Si surface, which provided a layer of intermediate density between water and the Si substrate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.278-278
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• 2009

A photovoltaic device consisting of arrays of radial p-n junction wires enables a decoupling of the requirements for light absorption and carrier extraction into orthogonal spatial directions. Each individual p-n junction wire in the cell is long in the direction of incident light, allowing for effective light absorption, but thin in orthogonal direction, allowing for effective carrier collection. To fabricate radial p-n junction solar cells, p or n-type vertical Si wire cores need to be produced. The majority of Si wires are produced by the vapor-liquid-solid (VLS) method. But contamination of the Si wires by metallic impurities such as Au, which is used for metal catalyst in the VLS technique, results in reduction of conversion efficiency of solar cells. To overcome impurity issue, top-down methods like noble metal catalytic etching is an excellent candidate. We used noble metal catalytic etching methods to make Si wire arrays. The used noble metal is two; Au and Pt. The method is noble metal deposition on photolithographycally defined Si surface by sputtering and then etching in various BOE and $H_2O_2$ solutions. The Si substrates were p-type ($10{\sim}20ohm{\cdot}cm$). The areas that noble metal was not deposited due to photo resist covering were not etched in noble metal catalytic etching. The Si wires of several tens of ${\mu}m$ in height were formed in uncovered areas by photo resist. The side surface of Si wires was very rough. When the distance of Si wires is longer than diameter of that Si nanowires are formed between Si wires. Theses Si nanowires can be removed by immersing the specimen in KOH solution. The optimum noble metal thickness exists for Si wires fabrication. The thicker or the thinner noble metal than the optimum thickness could not show well defined Si wire arrays. The solution composition observed in the highest etching rate was BOE(16.3ml)/$H_2O_2$(0.44M) in Au assisted chemical etching method. The morphology difference was compared between Au and Pt metal assisted chemical etching. The efficiencies of radial p-n junction solar Cells made of the Si wire arrays were also measured.

• Transactions on Electrical and Electronic Materials
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• v.16 no.6
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• pp.312-316
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• 2015

Through silicon via (TSV) technology holds the promise of chip-to-chip or chip-to-package interconnections for higher performance with reduced signal delay and power consumption. It includes high aspect ratio silicon etching, insulation liner deposition, and seamless metal filling. The desired etch profile should be straightforward, but high aspect ratio silicon etching is still a challenge. In this paper, we investigate the use of etch hard mask for finer TSVs etching to have clear definition of etched via pattern. Conventionally employed photoresist methods were initially evaluated as reference processes, and oxide and metal hard mask were investigated. We admit that pure metal mask is rarely employed in industry, but the etch result of metal mask support why hard mask are more realistic for finer TSV etching than conventional photoresist and oxide mask.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.6
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• pp.1465-1468
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• 2010

The wet etching is a process using chemical solution and occurring chemical reaction on substrate surface. when we do wet etching process, we have to consider stoichiometry, etching time and temperature of etchant for good resolution. In this experiment, we used Cr, Al andIndium-tin-oxide (ITO) metal and we deposited them with DC sputtering machine. The Cr thin film metal thickness is about $1300{\AA}$, ITO films show a low electrical resistance and high transmittance in the visible range of an optical spectrum and Ai film is used for signal line. We measured and analysed wet etching properties on the metal thin films.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1252-1254
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• 2005

Recently, PDP barrier ribs require the formation of complex structure so that they are usually formed by etching method. For producing the fine ribs structure, during the etching process the metal ions of matrix (glass) of barrier materials should be understood on the etching mechanism with etching condition. We analyzed the quantity of Pb, Si, and B ions from the etch solution as a function of etching time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.859-862
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• 2001

This study describes a selective Ag etching solution for use with pattern on the surface of copper. This etching solution uses potassium iodide and potassium sulfate as the ligand that coordinates to the metal ions and ferricyanide as the oxidant. The etching rate was depended on the concentration of co-ligands and time. But the etching rate wasn't depended on the pH(2∼6), and oxidant(K$_3$Fe(CN)$\_$6/). Complete etching of silver can be achieved rapidly within 90sec for 4.46${\mu}$m thick metal films when aqueous solutions containing K$_3$Fe(CN)$\_$6/, K$_2$S$_2$O$\_$8/ and KI was used. This etching solution was characteristic of anisotropic etching.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.5
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• pp.196-201
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• 2014

We investigated defects and surface polarity in AlN and GaN by using wet chemical etching. Therefore, the effectiveness and reliability of estimating the single crystals by defect selective etching in NaOH/KOH eutectic alloy have been successfully demonstrated. High-quality AlN and GaN single crystals were etched in molten NaOH/KOH eutectic alloy. The etching characteristics and surface morphologies were carried out by scanning electron microscope (SEM) and atomic force microscope (AFM). The etch rates of AlN and GaN surface were calculated by etching depth as a function of etching time. As a result, two-types of etch pits with different sizes were revealed on AlN and GaN surface, respectively. Etching produced hexagonal pits on the metal-face (Al, Ga) (0001) plane, while hexagonal hillocks formed on the N-face. On etching rate calibration, it was found that N-face had approximately 109 and 15 times higher etch rate than the metal-face of AlN and GaN, respectively. The size of etch pits increased with an increase of the etching time and they tend to merge together with a neighbouring etch pits. Also, the chemical mechanism of each etching process was discussed. It was found that hydroxide ion ($OH^-$) and the dangling bond of nitrogen play an important role in the selective etching of the metal-face and N-face.