• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.78-78
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• 2007

In semiconductor devices, Cu has been used for the formation of multilevel metal interconnects by the damascene technique. Also lower dielectric constant materials is needed for the below 65 nm technology node. However, the low-k materials has porous structure and they can be easily damaged by high down pressure during conventional CMP. Also, Cu surface are vulnerable to have surface scratches by abrasive particles in CMP slurry. In order to overcome these technical difficulties in CMP, electro-chemical mechanical planarization (ECMP) has been introduced. ECMP uses abrasive free electrolyte, soft pad and low down-force. Especially, electrolyte is an important process factor in ECMP. The purpose of this study was to characterize KOH and $KNO_3$ based electrolytes on electro-chemical mechanical. planarization. Also, the effect of additives such as an organic acid and oxidizer on ECMP behavior was investigated. The removal rate and static etch rate were measured to evaluate the effect of electro chemical reaction.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.73-78
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• 2010

This research is about the drying and curing characteristic of conductivity metallic ink on-line curing device in order to improve the curing time for productivity in RFID Gravure printing. The curing process is carried out to increase the electric conductivity after the metallic ink is printed on the substrate. The metal ink is composed of nano-sized silver or copper particles. In this research, the combined IR and Hot air curing system is used and its results is compared with those of oven, IR and Hot Air type respectively. Generally the curing time in the past is about 3 minutes. But the combined system (IR+Hot Air) in this research shows that curing time is less than 30 seconds. These results is much faster than those of other system. This study can be help to make Roll-to-Roll drying and curing process for mass and continuous production on-line.

• 한국재료학회지
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• 제33권10호
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• pp.385-392
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• 2023

A solution combustion process for the synthesis of hollandite (BaAl₂Ti₆O₁₆) powders is described. SYNROC (synthetic rock) consists of four main titanate phases: perovskite, zirconolite, hollandite and rutile. Hollandite is one of the crystalline host matrices used for the disposal of high-level radioactive wastes because it immobilizes Sr and Lns elements by forming solid solutions. The solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between a nitrate and organic fuel, generates an exothermic reaction and that heat converts the precursors into their corresponding oxide products in air. The process has high energy efficiency, fast heating rates, short reaction times, and high compositional homogeneity. To confirm the combustion synthesis reaction, FT-IR analysis was conducted using glycine with a carboxyl group and an amine as fuel to observe its bonding with metal element in the nitrate. TG-DTA, X-ray diffraction analysis, SEM and EDS were performed to confirm the formed phases and morphology. Powders with an uncontrolled shape were obtained through a general oxide-route process, confirming hollandite powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using these methods.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.100-101
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• 2012

The plasma damage free and room temperature processedthin film deposition technology is essential for realization of various next generation organic microelectronic devices such as flexible AMOLED display, flexible OLED lighting, and organic photovoltaic cells because characteristics of fragile organic materials in the plasma process and low glass transition temperatures (Tg) of polymer substrate. In case of directly deposition of metal oxide thin films (including transparent conductive oxide (TCO) and amorphous oxide semiconductor (AOS)) on the organic layers, plasma damages against to the organic materials is fatal. This damage is believed to be originated mainly from high energy energetic particles during the sputtering process such as negative oxygen ions, reflected neutrals by reflection of plasma background gas at the target surface, sputtered atoms, bulk plasma ions, and secondary electrons. To solve this problem, we developed the NBAS (Neutral Beam Assisted Sputtering) process as a plasma damage free and room temperature processed sputtering technology. As a result, electro-optical properties of NBAS processed ITO thin film showed resistivity of $4.0{\times}10^{-4}{\Omega}{\cdot}m$ and high transmittance (>90% at 550 nm) with nano- crystalline structure at room temperature process. Furthermore, in the experiment result of directly deposition of TCO top anode on the inverted structure OLED cell, it is verified that NBAS TCO deposition process does not damages to the underlying organic layers. In case of deposition of transparent conductive oxide (TCO) thin film on the plastic polymer substrate, the room temperature processed sputtering coating of high quality TCO thin film is required. During the sputtering process with higher density plasma, the energetic particles contribute self supplying of activation & crystallization energy without any additional heating and post-annealing and forminga high quality TCO thin film. However, negative oxygen ions which generated from sputteringtarget surface by electron attachment are accelerated to high energy by induced cathode self-bias. Thus the high energy negative oxygen ions can lead to critical physical bombardment damages to forming oxide thin film and this effect does not recover in room temperature process without post thermal annealing. To salve the inherent limitation of plasma sputtering, we have been developed the Magnetic Field Shielded Sputtering (MFSS) process as the high quality oxide thin film deposition process at room temperature. The MFSS process is effectively eliminate or suppress the negative oxygen ions bombardment damage by the plasma limiter which composed permanent magnet array. As a result, electro-optical properties of MFSS processed ITO thin film (resistivity $3.9{\times}10^{-4}{\Omega}{\cdot}cm$, transmittance 95% at 550 nm) have approachedthose of a high temperature DC magnetron sputtering (DMS) ITO thin film were. Also, AOS (a-IGZO) TFTs fabricated by MFSS process without higher temperature post annealing showed very comparable electrical performance with those by DMS process with $400^{\circ}C$ post annealing. They are important to note that the bombardment of a negative oxygen ion which is accelerated by dc self-bias during rf sputtering could degrade the electrical performance of ITO electrodes and a-IGZO TFTs. Finally, we found that reduction of damage from the high energy negative oxygen ions bombardment drives improvement of crystalline structure in the ITO thin film and suppression of the sub-gab states in a-IGZO semiconductor thin film. For realization of organic flexible electronic devices based on plastic substrates, gas barrier coatings are required to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency flexible AMOLEDs needs an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}gm^{-2}day^{-1}$. The key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required (under ${\sim}10^{-6}gm^{-2}day^{-1}$) is the suppression of nano-sized defect sites and gas diffusion pathways among the grain boundaries. For formation of high quality single inorganic gas barrier layer, we developed high density nano-structured Al2O3 single gas barrier layer usinga NBAS process. The NBAS process can continuously change crystalline structures from an amorphous phase to a nano- crystalline phase with various grain sizes in a single inorganic thin film. As a result, the water vapor transmission rates (WVTR) of the NBAS processed $Al_2O_3$ gas barrier film have improved order of magnitude compared with that of conventional $Al_2O_3$ layers made by the RF magnetron sputteringprocess under the same sputtering conditions; the WVTR of the NBAS processed $Al_2O_3$ gas barrier film was about $5{\times}10^{-6}g/m^2/day$ by just single layer.

• 한국결정성장학회지
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• 제19권5호
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• pp.251-255
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• 2009

나노사이즈의 귀금속을 $TiO_2$ 매트릭스에 균질하게 분산 시킨 구조는 염료감응형 태양전지의 유망한 광전극 특성을 나타내는 것으로 보고되고 있다. 이와 같은 금 및 백금 나노미립자를 균질하게 분산된 구조의 광전극을 제작하기 위하여 석영 및 ITO 기판위에 동시스퍼터법에 의하여 박막을 합성 하였다. XRD분석을 통하여 상분석을 수행 한 결과 합성된 나노컴포지트는 Rutile상이 지배적인 결정 구조를 나타냈으며 열처리를 $600^{\circ}C$까지 진행함에 따라 $TiO_2$ 결정성의 향상 및 귀금속인 금 및 백금의 나노미립자가 증가 하는 결과를 나타내었다. 귀금속인 금 및 백금이 분산된 $TiO_2$ 광전극에서는 자외선(UV) 영역을 포함하여 가시광(VIS) 영역의 빛의 조사에 광전류 응답 특성을 발현 하였다. 가시광선 영역에서 발현된 광전류 응답 특성은 나노사이즈로 분산된 금 및 백금 금속과 $TiO_2$와의 계면 준위에 기인 한 것으로 판명 되었다.

• 한국재료학회지
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• 제22권5호
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• pp.243-248
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• 2012

ZrN nanoparticles were prepared by an exothermic reduction of $ZrCl_4$ with $NaN_3$ in the presence of NaCl flux in a nitrogen atmosphere. Using a solid-state combustion approach, we have demonstrated that the zirconium nitride nanoparticles synthesis process can be completed in only several minutes compared with a few hours for previous synthesis approaches. The chemistry of the combustion process is not complex and is based on a metathesis reaction between $ZrCl_4$ and $NaN_3$. Because of the low melting and boiling points of the raw materials it was possible to synthesize the ZrN phase at low combustion temperatures. It was shown that the combustion temperature and the size of the particles can be readily controlled by tuning the concentration of the NaCl flux. The results show that an increase in the NaCl concentration (from 2 to 13 M) results in a temperature decrease from 1280 to $750^{\circ}C$. ZrN nanoparticles have a high surface area (50-70 $m^2/g$), narrow pore size distribution, and nano-particle size between 10 and 30 nm. The activation energy, which can be extracted from the experimental combustion temperature data, is: E = 20 kcal/mol. The method reported here is self-sustaining, rapid, and can be scaled up for a large scale production of a transition metal nitride nanoparticle system (TiN, TaN, HfN, etc.) with suitable halide salts and alkali metal azide.

• Bulletin of the Korean Chemical Society
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• 제18권8호
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• pp.831-840
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• 1997

Core/shell structured composite metal oxides of Fe2O3/MgO were prepared by thermal decomposition of Fe(acac)3 adsorbed on the surface of MgO cores. The morphology of the composites conformed to that of the MgO used as the cores. Broad powder X-ray diffraction peaks shifted toward larger d, large BET surface area (∼350 m2/g), and the size of crystalline domains in nano range (4 nm), all corroborate to the nanocrystallinity of the Fe2O3/MgO composite which was prepared by using nanocrystalline MgO as the core. By use of microcrystalline MgO as the core, microcrystalline Fe2O3/MgO composite was prepared, and it had small BET surface area of less than 35 m2/g. AFM measurements on nanocrystalline Fe2O3/MgO showed a collection of spherical aggregates (∼80 nm dia) with a very rough surface. On the contrary, microcrystalline Fe2O3/MgO was a collection of plate-like flat crystallites with a smooth surface. The nitrogen adsorption-desorption behavior indicated that microcrystalline Fe2O3/MgO was nonporous, whereas nanocrystalline Fe2O3/MgO was mesoporous. Bimodal distribution of the pore size became unimodal as the layer of Fe2O3 was applied to nanocrystalline MgO. The macropores in a wide distribution which the nanocrystalline MgO had were absent in the nanocrystalline Fe2O3/MgO. The decomposition of CCl4 was largily enhanced by the overlayer of Fe2O3 on nanocrystalline MgO making the reaction between nanocrystalline Fe2O3/MgO and CCl4 be nearly stoichiometric. The reaction products were environmentally benign MgCl2 and CO2. Such an enhancement was not attainable with the microcrystalline samples. Even for the nanocrystalline MgO, the enhancement was not attained, if not with the Fe2O3 layer. Without the layer of Fe2O3, it was observed that the nanocrystalline domain of the MgO transformed into microcrystalline one as the decomposition of CCl4 proceeded on its surface. It appeared that the layer of Fe2O3 on the particles of nanocrystalline Fe2O3/MgO blocked the transformation of the nanocrystalline domain into microcrystalline one. Therefore, in order to attain stoichiometric reaction between CCl4 and Fe2O3/MgO core/shell structured composite metal oxide, the morphology of the core MgO has to be nanocrystalline, and also the nanocrystalline domains has to be sustained until the core was exhausted into MgCl2.

• 전기화학회지
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• 제11권3호
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• pp.176-183
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• 2008

본 연구에서는 8족 금속 원소인 osmium을 중심금속으로 4가지의 착물을 합성하였다. 합성한 착물은 ${[Os(bpy)}_2{(ap-im)Cl]}^{+/2+}$, ${[Os(dme-bpy)}_2{(ap-im)Cl]}^{+/2+}$, ${[Os(dmo-bpy)}_2{(ap-im)Cl]}^{+/2+}$, ${[Os(dcl-bpy)}_2{(ap-im)Cl]}^{+/2+}$이다. 합성된 착물을 순환전압전류법을 포함한 다양한 전기화학분석방법을 이용하여 전기적 성질을 조사하여 작용기에 따른 전위의 변화를 다음의 전위구간에서 $E_p$:$-0.06\;V{\sim}0.313\;V$ vs. Ag/AgCl 확인하였다. 합성한 화합물을 전기적 흡착방법으로 고정된 금나노입자(gold nano-particles)를 전극 위에 자기조립방식으로 고정화를 시켰다. 당과 당 분해효소(Glucose Oxidase, GOx)에 의한 촉매반응의 전류를 확인하였고, glucose농도에 따른 변화하는 전류의 양도 확인하였다. 마지막으로 고정된 4가지의 osmium complex는 서로 다른 전위로 인하여 촉매전류의 양이 달라지는 것을 알 수 있었고, 이로 인해 redox complex의 전위가 촉매반응에 미치는 영향을 확인 할 수 있었다.

• 한국재료학회지
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• 제20권11호
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• pp.611-616
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• 2010

A cobalt oxide - tin oxide nanocomposite based gas sensor on an $SiO_2$ substrate was fabricated. Granular thin film of tin oxide was formed by a rheotaxial growth and thermal oxidation method using dc magnetron sputtering of Sn. Nano particles of cobalt oxide were spin-coated on the tin oxide. The cobalt oxide nanoparticles were synthesized by polymer-assisted deposition method, which is a simple cost-effective versatile synthesis method for various metal oxides. The thickness of the film can be controlled over a wide range of thicknesses. The composite structures thus formed were characterized in terms of morphology and gas sensing properties for reduction gas of $H_2$. The composites showed a highest response of 240% at $250^{\circ}C$ upon exposure to 4% $H_2$. This response is higher than those observed in pure $SnO_2$ (90%) and $Co_3O_4$ (70%) thin films. The improved response with the composite structure may be related to the additional formation of electrically active defects at the interfaces. The composite sensor shows a very fast response and good reproducibility.

• 상하수도학회지
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• 제25권2호
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• pp.201-212
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• 2011

Nanotechnology is the applied science which develops new materials and systems sized within 1 to 100 nanometer, and improves their physical, chemical, and biological characteristics by manipulating on an atomic and molecular scale. This nanotechnology has been applied to wide spectrum of industries resulting in production of various nanoparticles. It is expected that more nanoparticles will be generated and enter to natural water bodies, imposing great threat to potable water resources. However their toxicity and treatment options have not been throughly investigated, despite the significant growth of nanotechnology-based industries. The objective of this study is to provide fundamental information for the management of nanoparticles in water supply systems through extensive literature survey. More specifically, two types of nanoparticles are selected to be a potential problem for drinking water treatment. They are carbon nanoparticles such as carbon nanotube and fullerene, and metal nanoparticles including silver, gold, silica and titanium oxide. In this study, basic characteristics and toxicity of these nanoparticles were first investigated systematically. Their monitoring techniques and treatment efficiencies in conventional water treatment plants were also studied to examine our capability to mitigate the risk associated with nanoparticles. This study suggests that the technologies monitoring nanopartilces need to be greatly improved in water supply systems, and more advanced water treatment processes should be adopted for better control of these nanoparticles.