• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.146-152
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• 2006

In micro electrochemical machining (ECM), electrodes should be prevented from unfavorable oxide and Passive layer formation on the machined surface or overall corrosion of the entire surface. Generally, metal electrodes corrode, passivate or dissolve in the electrochemical cell according to the electrode potential. Therefore, each electrode must maintain its stable potential. Tn this paper, the stable electrode potentials of tool and workpiece were determined using the potentiodynamic polarization test and verified experimentally considering machining stability and surface quality. Stable workpiece electrode potentials of two different passive materials of 304 stainless steel and nickel were determined in the 0.1 M sulfuric acid. Experimental results show good machined surface and fast machining rate using the determined electrode potentials.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.7
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• pp.15-22
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• 1997

A 10Gbit/s limiting amplifier IC for optical transmission system was implemented with AlGaAs HBT (heterojunction bipolar transistor) technology. HBTs with 2x10.mu. $m^{2}$ and 6x20.mu. $m^{2}$ emitter size were used. The HBT structures are based on metal-organic chemical vapor deposition (MOCVD) epitxy and employ a mesa structure with self-aligned emitter/base and sidewall dielectric passivation. IC was designed to support differnetial input and output. Small signal performance of the packaged IC showed 26dB gain and $f_{3dB}$ of 8GHz. A single ouput has 800m $V_{p-p}$ swing with more than 26dB dynamic range. The performance of the limiting amplifier was verified through single mode fiber320km transmission link test.est.

• Journal of Industrial Technology
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• v.19
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• pp.101-105
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• 1999

Ultra thin $Ta_2O_5$ gate dielectrics were prepared by RTMOCVD (rapid thermal metal organic chemical vapor deposition) using Ta source $TaC_{12}H_{30}O_5N$ and $O_2$ gaseous mixtures. As a result, $Ta_2O_5$ thin films showed significantly low leakage current compared to $SiO_2$ of identical thickness, which was due to the stabilization of the interfacial layer by NO ($SiO_xN_y$) passivation layer. The conduction of leakage current in $Ta_2O_5$ thin films was described by the hopping mechanism of Poole-Frenkel (PF) type.

• Journal of Welding and Joining
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• v.15 no.5
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• pp.124-133
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• 1997

Corrosion behavior of welded SWS400 steel used for bridges was studied in a range of the acid-rain environment using immersion, potentiodynamic polartization, polarization resistance, and galvanic corrosion tests. The SWS400 steel exhibited active corrosion behavior in the range of acid-rain environment, i.e. no passivation. As the results of immersion corrosion test, Tafel extrapolation method, and polarization resistance measurement, the average corrosion rats of the steels were 0.31-0.72 mm/year in the pH of 4-5, and 0.17 mm/yera in the pH 6, respectively. The steel showed a resistance to corrosion in the pH 6. The observed active behavior of SWS400 steel in chloride-containing environment indicated that the chloride ions exerts a detrimental influence on the formation of passive films. Galvanic corrosion was observed between the weld and the base metals because the weld is anodic to the base metal.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.383-386
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• 1998

After etching Al-Cu alloy films using SiC1$_4$/Cl$_2$/He/CHF$_3$ plasma, a corrosion phenomenon on the metal surface has been studied with XPS (X-ray photoelectron spectroscopy) and SEM (Scanning electron microscopy). In Al-Cu alloy system, the corrosion occurs rapidly on the etched surface by residual chlorine atoms. To prevent the corrosion, CHF$_3$ plasma treatment subsequent to the etched has been carried out. A passivation layer is formed by fluorine-related compounds on the etched Al-Cu surface after CHF$_3$ and SF$_{6}$ treatment, and the layer supresses effectively the corrosion on the surface as the CHF$_3$ and SF$_{6}$ treatment pressure increases. The corrosion could be suppressed successfully with CHF$_3$ and SF6 treatment in the pressure of 300mTorr.orr.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.249-249
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• 2010

The effect of forming a passivation layer was investigated in superconformal Cu gap-filling of the nano-scale trench with atomic-layer deposited (ALD)-Ru glue layer. It was discovered that the nucleation and growth of Cu during metal-organic chemical vapor deposition (MOCVD) were affected by hydrogen plasma treatments. Specifically, as the plasma pretreatment time increased, Cu nucleation was suppressed proportionally. XPS and Thermal Desorption Spectroscopy indicated that hydrogen atoms passivate the Ru surface, which leads to suppression of Cu nucleation owing to prevention of adsorption of Cu precursor molecules. For gap-fill property, sub 60-nm ALD Ru trenches without the plasma pretreatment was blocked by overgrown Cu after the Cu deposition. With the plasma pretreatment, superconformal gap filling of the nano-scale trenches was achieved due to the suppression of Cu nucleation near the entrances of the trenches. Even the plasma pretreatment with bottom bias leads to the superconformal gap-filling.

• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.67-71
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• 2011

The cathodic active material of $Li/SO_2Cl_2$ battery is $SO_2Cl_2$, which is the solvent of an electrolyte. It is referred to as a catholyte, a compound word of cathode and electrolyte. As the battery discharges, the catholyte burns out. And thus, the characteristics of the $SO_2Cl_2$ in the battery determine the capacity. In addition, the transition minimum voltage (TMV) and the voltage delay deviation of $Li/SO_2Cl_2$ battery are due to the passivation film formed by the reaction between an electrolyte and Li. Impurities in the electrolyte, such as moisture or heavy metal ions, will accelerate the growth of the passivation film. Therefore, a technology must be established to purify an electrolyte and to ensure the effectiveness of the purification method. In this research, $LiAlCl_4/SO_2Cl_2$ was manufactured using $AlCl_3$ and LiCl. Its concentration, the amount of moisture, and the metal amount were evaluated using an ionic conductivity meter, a colorimeter, and FT-IR.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.6-11
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• 1999

Dialkylamine (di-)nitrobenzoates as vapor corrosion inhibitor were synthesized with dialkylamines and (di-)nitrobenzoic acids. The compounds were analyzed by elemental analyzer, FT-IR and $^1H$-NMR spectrophotometer. Corrosion inhibition of synthetic compounds and additives [$(NH_4)_2CO_3$, $NaHCO_3$] against ferrous and non-ferrous metal was investigated by potentiostatic method [1% (w/v) corrosion inhibitor in 1M $Na_2SO_4$ aqueous solution] respectively. For corrosion inhibition of ferrous metal, dialkylamine 4-nitrobenzoates were better inhibitor than dialkylamine 3, 5-dinitrobenzoates, the passivating current density ($i_p$) of dialkylamine 4-nitrobenzoate was shown $4.78mA/cm^2$. While, for non-ferrous metal, dialkylamine 3, 5-dinitrobenzoates were better, those of dipropylamine 3, 5-dinitrobenzoate and hexamethyleneimine 3, 5-dinitrobenzoate were shown 36 and $37mA/cm^2$. Additive effect of $(NH_4)_2CO_3$ and $NaHCO_3$ for corrosion inhibition of ferrous metal was excellent but that of non-ferrous metal was not. Optimum ratios of diethylamine 4-nitrobenzoate with $(NH_4)_2CO_3$ and $NaHCO_3$ were 4 : 6 and 5 : 5 (V/V), and passivating current densities ($i_p$) of the mixtures were shown 0.26 and $0.85mA/cm^2$, respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.449-457
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• 2012

The program/erase (P/E) cyclic endurances including bias temperature instability (BTI) behaviors of Metal-$Al_2O_3$-Nitride-Oxide-Semiconductor (MANOS) memories are investigated in comparison with those of Semiconductor-Oxide-Nitride-Oxide-Semiconductor (SONOS) memories. In terms of BTI behaviors, the SONOS power-law exponent n is ~0.3 independent of the P/E cycle and the temperature in the case of programmed cell, and 0.36~0.66 sensitive to the temperature in case of erased cell. Physical mechanisms are observed with thermally activated $h^*$ diffusion-induced Si/$SiO_2$ interface trap ($N_{IT}$) curing and Poole-Frenkel emission of holes trapped in border trap in the bottom oxide ($N_{OT}$). In terms of the BTI behavior in MANOS memory cells, the power-law exponent is n=0.4~0.9 in the programmed cell and n=0.65~1.2 in the erased cell, which means that the power law is strong function of the number of P/E cycles, not of the temperature. Related mechanism is can be explained by the competition between the cycle-induced degradation of P/E efficiency and the temperature-controlled $h^*$ diffusion followed by $N_{IT}$ passivation.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.291-296
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• 2007

The corrosion of metals and alloys in flowing liquids can be classified into uniform corrosion and localized corrosion which may be categorized as follows. (1) Localized corrosion of the erosion-corrosion type: the protective oxide layer is assumed to be removed from the metal surface by shear stress or turbulence of the fluid flow. A macro-cell may be defined as a situation in which the bare surface is the macro-anode and the other surface covered with the oxide layer is the macro-cathode. (2) Localized corrosion of the differential flow-velocity corrosion type: at a location of lower fluid velocity, a thin and coarse oxide layer with poor protective qualities may be produced because of an insufficient supply of oxygen. A macro-cell may be defined as a situation in which this surface is the macro-anode and the other surface covered with a dense and stable oxide layer is the macro-cathode. (3) Localized corrosion of the active/passive-cell type: on a metal surface a macro-cell may be defined as a situation in which a part of it is in a passivation state and another in an active dissolution state. This situation may arise from differences in temperature as well as in the supply of the dissolved oxygen. Compared to uniform corrosion, localized corrosion tends to involve a higher wall thinning rate (corrosion rate) due to the macro-cell current as well as to the ratio of the surface area of the macro-anode to that of the macro-cathode, which may be rationalized using potential vs. current density diagrams. The three types of localized corrosion described above can be reproduced in a Jet-in-slit test by changing the flow direction of the test liquid and arranging environmental conditions in an appropriate manner.