• Transactions on Electrical and Electronic Materials
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• 제4권2호
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• pp.29-34
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• 2003

Ferroelectric YMnO$_3$ thin films were etched with Ar/C1$_2$ and CF$_4$/C1$_2$ Plasma. The maximum etch rate of YMnO$_3$ thin film was 300 $\AA$/min at a Cl$_2$/Ar gas mixing ratio of 8/2, an RF power of 800 W, a do bias of-200 V, a chamber pressure of 15 mTorr, and a substrate temperature of 3$0^{\circ}C$. From the X-ray photoelectron spectroscopy (XPS) analysis, yttrium was not only etched by chemical reactions with Cl atoms, but also assisted by Ar ion bombardments in Ar/C1$_2$ plasma. In CF$_4$/C1$_2$ plasma, yttrium formed nonvolatile YF$_{x}$ compounds and remained on and the etched surface of YMnO$_3$. Manganese etched effectively by forming volatile MnCl$_{x}$ and MnF$_{y}$. From the X-ray diffraction (XRD) analysis, the (0004) diffraction peak intensity of the YMnO$_3$ thin film etched in Ar/Cl$_2$ plasma shows lower than that in CF$_4$/Cl$_2$ plasma. It indicates that the crystallinty of the YMnO$_3$ thin film is more easily damaged by the Af ion bombardment than the changes of stoichiometry due to nonvolatile etch by-products.cts.s.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.787-790
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• 2003

A rf triode magnetron sputtering system is designed and installed its construction in vacuum chamber. In order to calibrate the rf triode magnetron sputtering for thin films deposition processes, the effects of different glow discharge conditions were investigated in terms of the deposition rate measurements. The basic parameters for calibrating experiment in this sputtering system are rf power input, gas pressure, plasma current, and target-to-substrate distance. Because a knowledge of the deposition rate is necessary to control film thickness and to evaluate optimal conditions which are an important consideration in preparing better thin films, the deposition rates of copper as a testing material under the various sputtering conditions are investigated. Furthermore, a triode sputtering system designed in our team is simulated by the SIMION program. As a result, it is sure that the simulation of electron trajectories in the sputtering system is confined directly above the target surface by the force of $E{\times}B$ field. Finally, some teats with the above 4 different sputtering conditions demonstrate that the deposition rate of rf triode magnetron sputtering is relatively higher than that of the conventional sputtering system. This means that the higher deposition rate is probably caused by a high ion density in the triode and magnetron system. The erosion area of target surface bombarded by Ar ion is sputtered widely on the whole target except on both magnet sides. Therefore, the designed rf triode magnetron sputtering is a powerful deposition system.

• 한국전기전자재료학회논문지
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• 제16권6호
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• pp.449-453
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• 2003

Ferroelectric YMnO$_3$ thin films were etched with Ar/Cl$_2$ and CF$_4$/Cl$_2$ inductively coupled plasma (ICP). The maximum etch rate of YMnO$_3$ thin film was 300 $\AA$/min at a Ar/Cl$_2$ gas mixing ratio of 2/8, a RF power of 800 W, a DE bias of 200 V, a chamber pressure of 15 mTorr, and a substrate temperature of 30 $^{\circ}C$. From the X-ray photoelectron spectroscopy (XPS) analysis, yttrium etched by chemical reactions with Cl radicals assisted by Ar ion bombardments in Ar/Cl$_2$ plasma. In CF$_4$/Cl$_2$ plasma, yttrium are remained on the etched surface of YMnO$_3$ and formed of nonvolatile YF$_{x}$ compounds manganese etched effectively by chemical reactions with Cl and F radicals. From the X-ray diffraction (XRD) analysis, the (0004) diffraction peak intensity of the YMnO$_3$ thin film etched in Ar/Cl$_2$ plasma shows lower value than that in CF$_4$/Cl$_2$ plasma. It indicates that the crystallinty of YMnO$_3$ thin film is more easily damaged by the Ar ion bombardment than the changes of stoichiometry due to nonvolatile etch by-products.s.

• 한국대기환경학회지
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• 제26권4호
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• pp.432-442
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• 2010

Ammonia is a very important constituent of the atmospheric environment because it is the most dominant gaseous alkaline species present in the atmosphere. Ammonia is known to affect ecosystems at relatively low concentration. Ammonia flux from livestock facilities can be regulated by a number of environmental factors (pH, ammonium ion, temperature, wind speed, etc). The increases in wind speed above manure from 0.0 m/s to 1.0 7m/s resulted in 2.5 times increases in ammonia flux. Wind speed and ammonia flux showed 0.982. A linear relationship with a correlation coefficient (r=0.982). When manure temperature increased from $3^{\circ}C$ to $36^{\circ}C$, the manure pH decreased approximately 0.30 to 0.46. As wind speed above the manure increased from 0.0 m/s to 1.07 m/s, ammonia flux increased approximately 2.5 times. The increasing manure temperature from $3^{\circ}C$ to $10^{\circ}C$, raised ammonia flux from 2.0 to 3.6 times (2.6 times in average similarly). The increases of manure temperature from $3^{\circ}C$ to $25^{\circ}C$ increased ammonia flux from 5.7 to 12.9 times (8.5 times in average). In this study, the correlation coefficient between ammonia flux and manure temperature was found from 0.972 to 0.989. Results of our research showed that ammonium ion concentration, pH of manure and wind speed were important factors in controlling the ammonia flux from manure livestock facilities.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.159-162
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• 2002

Ferroelectric $YMnO_{3}$ thin films were etched with $Ar/Cl_{2}$ and $CF_{4}/Cl_{2}$ inductivly coupled plasma (ICP). The maximum etch rate of $YMnO_{3}$ thin film was $300{\AA}/min$ at a $Ar/Cl_{2}$ gas mixing ratio of 2/8, a RF power of 800 W, a dc bias of 200 V, a chamber pressure of 15 mTorr, and a substrate temperature of ${30^{\circ}C}$. From the X-ray photoelectron spectroscopy (XPS) analysis ， yttrium not only etched by chemical reactions with Cl radicals, but also assisted by Ar ion bombardments in $Ar/Cl_{2}$ plasma. In $CF_{4}/Cl_{2}$ plasma, yttrium are remained on the etched surface of $YMnO_{3}$ and formed of nonvolatile YFx compounds Manganese etched effectively by chemical reactions with Cl and F radicals. From the X-ray diffraction (XRD) analysis, the (0004) diffraction peak intensity of the $YMnO_{3}$ thin film etched in $Ar/Cl_{2}$ plasma shows lower value than that in $CF_{4}/Cl_{2}$ plasma. It is indicates that the crystallinty of $YMnO_{3}$ thin film is more easily damaged by the Ar ion bombardment than the changes of stoichiometry due to nonvolatile etch by-products.

• Journal of Pharmaceutical Investigation
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• 제26권1호
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• pp.43-53
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• 1996

The objective of this study was to determine whether 4-phenylazobezyloxycarbonyl-Pro-Leu-Gly-Pro-D-Arg (Pz-peptide), an enhancer of hydrophilic solute permeability in the intestine, could elevate the paracellular permeability of hydrophilic drugs across cornea and conjunctiva in the rabbit. The in-vitro penetration of hydrophilic drugs (mannitol, atenolol) and lipophilic drug (propranolol) across the rabbit cornea and conjunctiva was studied either in the presence or absence of 3 mM Pz-peptide. Drug penetration was evaluated using the modified Ussing chamber. The conjunctiva was more permeable than the cornea to all drugs. Pz-peptide showed enhanced effects on the drug transport across cornea and conjunctiva in a concentration dependent manner. Effects or ion transport inhibitor on the mannitol penetration were then investigated. Mannitol penetration was not changed by serosal addition of $100\;{\mu}M$ ouabain, suggesting that $Na^+/K^+$ ion tranporter was not involved in the Pz-peptide induced elevation of paracellular drug permeability. Furthermore, effects of Pz-peptide and EDTA on the transport of atenolol and propranolol into the ocular tissues or blood circulation after its administration into both eyes were investigated. EDTA showed enhanced effect on propranolol transport into the ocular tissues, but Pz-peptide did not show significant difference. Systemic absorption of propranolol by the addition of EDTA or Pz-peptide was not changed. On the other hand, EDTA and Pz-peptide elavated the atenolol transport into the ocular tissues. The transport of atenolol into the blood circulation was also enhanced by the addition of EDTA, but no effect was observed by the addition of Pz-peptide. The above findings suggest that Pz-peptide would be used as an paracellular pathway enahncer of hydrophilic drugs into the eye, without affecting the systemic absortion of topically applied opthalmic drugs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.41-43
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• 1999

Among the feffoelectric thin films that have been widely investigated for ferroelectric random access memory (FRAM) applications, SrBi$_2$Ta$_2$$O_{9}$ thin film is appropriate to memory capacitor materials for its excellent fatigue endurance. However, very few studies on etch properties of SBT thin film have been reported although dry etching is an area that demands a great deal of attention in the very large scale integrations. In this study, the a SrBi$_2$Ta$_2$$O_{9}$ thin films were etched by using magnetically enhanced inductively coupled Ar/CHF$_3$ plasma. Etch properties, such as etch rate, selectivity, and etched profile, were measured according to gas mixing ratio of CHF$_3$(Ar$_{7}$+CHF$_3$) and the other process conditions were fixed at RF power of 600 W, dc bias voltage of 150 V, chamber pressure of 10 mTorr. Maximum etch rate of SBT thin films was 1750 A77in, under CHF$_3$(Ar+CHF$_3$) of 0.1. The selectivities of SBT to Pt and PR were 1.35 and 0.94 respectively. The chemical reaction of etched surface were investigated by X-ray photoelectron spectroscopy (XPS) analysis. The Sr and Ta atoms of SBT film react with fluorine and then Sr-F and Ta-F were removed by the physical sputtering of Ar ion. The surface of etched SBT film with CHF$_3$(Ar+CHF$_3$) of 0.1 was analyzed by secondary ion mass spectrometer (SIMS). Scanning electron microscopy (SEM) was used for examination of etched profile of SBT film under CHF$_3$(Ar+CHF$_3$) of 0.1 was about 85˚.85˚.˚.

• 한국진공학회지
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• 제7권2호
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• pp.161-168
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• 1998

Taguchi가 제안한 강건설계 및 연구자의 주관에 의존하는 통상적인 실험방법을 병 행하여 CH4/H2 유도결합 고밀도 플라즈마를 이용한 InP 소재의 반응성이온에칭에 있어 공 정변수들이 식각특성에 미치는 영향을 분석하고 적정조건을 도출하였다. 연구 결과 ICP전력 은 표면거칠기와 측벽수직도, bias 전력은 식각속도와 수직도에, CH4분율은 수직도와 식각 속도, 석영창과 시료 사이의 거리는 표면 거칠기에 영향을 주는 변수로 작용하였고, 식각속 도에 가장 크게 영향을 주는 변수는 공정압력임을 알 수 있었다. 결과적으로 ICP Power 700W, bias Power 150W, 시편/coil 거리 14cm, 압력 7.5mTorr, 15% $CH_4$의 적정조건에서 시간당 약 3.1$\mu\textrm{m}$의 식각속도와 미려한 표면을 얻어, 기존의 반응성 이온 식각(RIE)과 비교하 여 1.5배 이상의 식각속도를 얻을 수 있었다.

• 한국해양공학회지
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• 제30권5호
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• pp.356-360
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• 2016

Recently, the lifetime extension of nuclear power plants has been considered. Thus, it is necessary to consider facility safety management and economic management. However, when the bolts in nuclear power plants are replaced and the turbines of nuclear power plant are disassembled, numerous problems are found in relation to stuck bolts in clamping parts. In order to solve these problems, a hybrid vacuum chamber was first designed and manufactured. It can perform arc ion plating and sputtering, which were used to deposit Ti/TiN on an A913 B7 bolt. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were conducted to determine the composition and characteristics of the bolt, and tests were conducted to determine how long the bolt could endure under various conditions in a nuclear power plant. The SEM and XRD results clearly showed a continual and even coating layer. When this TiN-coated bolt is used in a nuclear power plant, the lifetime can be extended compared to a conventional bolt, but it is necessary to determine what additional properties are required.

• Corrosion Science and Technology
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• 제18권5호
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• pp.206-211
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• 2019

Silicon carbide (SiC) thin films become superhard when they have microstructures of nanocolumnar crystalline grains (NCCG) with an intergranular amorphous SiC matrix. We investigated the role of ion bombardment and deposition temperature in forming the NCCG in SiC thin films. A direct-current (DC) unbalanced magnetron sputtering method was used with pure Ar as sputtering gas to deposit the SiC thin films at fixed target power of 200 W and chamber pressure of 0.4 Pa. The Ar ion bombardment of the deposited films was conducted by applying a negative DC bias voltage 0-100 V to the substrate during deposition. The deposition temperature was varied between room temperature and $450^{\circ}C$. Above a critical bias voltage of -80 V, the NCCG formed, whereas, below it, the SiC films were amorphous. Additionally, a minimum thermal energy (corresponding to a deposition temperature of $450^{\circ}C$ in this study) was required for the NCCG formation. Transmission electron microscopy, Raman spectroscopy, and glancing angle X-ray diffraction analysis (GAXRD) were conducted to probe the samples' structural characteristics. Of those methods, Raman spectroscopy was a particularly efficient non-destructive tool to analyze the formation of the SiC NCCG in the film, whereas GAXRD was insufficiently sensitive.