• Journal of Advanced Marine Engineering and Technology
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• 제32권2호
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• pp.262-267
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• 2008

Plasma immersion ion beam (PIIB) nitriding process is an environmentally benign and cost-effective process, and offers the potential of producing high dose of nitrogen ions in a way of simple, fast and economic technique for the high plasma flux treatment of large surface area with nitrogen ion source gas. In this report PIIB nitriding technique was used for nitriding on austenite stainless steel of AISI304 with plasma treatment at $250{\sim}500^{\circ}C$ for 4 hours, and with the working gas pressure of $2.67{\times}10^{-1}$ Pa in vacuum condition. This PIIB process might prove the advantage of the low energy high flux of ion bombardment and enhance the tribological or mechanical properties of austenite stainless steel by nitriding, Furthermore, PIIB showed a useful surface modification technique for the nitriding an irregularly shaped three dimensional workpiece of austenite stainless steel and for the improvement of surface properties of AISI 304, such as hardness and strength

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.247.1-247.1
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• 2014

The capacitive coupled plasma is used widely in the semiconductor industries. Especially, the uniformity of the industrial plasma is heavily related with defect ratio of devices. Therefore, the industries need the capacitive coupled plasma source which can generate the uniform plasma and control the plasma's uniformity. To achieving the uniformity of the large area plasma, we designed multi-powered electrodes. We controlled the uniformity by controlling the power of each electrode. After this work, we started to research another concept of the plasma device. We make the plasma chamber that has multi-ground electrodes imaginary (CST microwave studio) and simulate the electric field. The shape of the multi-ground electrodes is ring type, and it is same as the shape of the multi-power electrodes that we researched before. The diameter of the side electrode's edge is 300mm. We assumed that the plasma uniformity is related with the impedance of ground electrodes. Therefore we simulated the imaginary chamber in three cases. First, we connected L (inductor) and C (capacitor) at the center of multi-ground electrodes. Second, we changed electric conductivity of multi-ground electrode. Third, we changed the insulator's thickness between the center ground electrode and the side ground electrode. The driving frequency is 2, 13.56 and 100 MHz. We switched our multi-powered electrode system to multi-ground electrode system. After switching, we measured the plasma uniformity after installing a variable vacuum capacitor at the ground line. We investigate the effect of ground electrodes' impedance to plasma uniformity.

• 한국표면공학회지
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• 제33권2호
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• pp.69-76
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• 2000

The rf plasma chemical vapor deposition is a common method employed for diamond or amorphous carbon deposition. Diamond possesses the strongest bonding, as exemplified by a number of unique properties-extraordinary hardness, high thermal conductivity, and a high melting tempera tore. Therefore, it is very important to investigate the synthesis of semiconducting diamond and its use as semiconductor devices. An inductively coupled rf plasma CVD system for producing amorphous carbon films were developed. Uniform temperature and concentration profiles are requisites for the deposition of high quality large-area films. The system consists of rf matching network, deposition chamber, pumping lines for gas system. Gas mixtures with methane, and hydrogen have been used and Si (100) wafers used as a substrate. Amorphous carbon films were deposited with methane concentration of 1.5% at the process pressure of S torr~20 torr, and process temperature of about $750^{\circ}C$. The nucleation and growth of the amorphous carbon films have been characterized by several methods such as SEM and XRD.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.891-894
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• 1999

ICP reactor produces high-density and high-uniformity plasma in large area, are has excellent characteristic of direction in the case of etching. Until now, many algorithms used one mesh method. These algorithms are not appropriate for sub 0.1 ${\mu}{\textrm}{m}$ device technologies which should deal with each ion. These algorithms could not present exactly straggle and interaction between projectile ions and could not consider reflection effects due to interactions among next projectile ions, reflected ions and sputtering ions, simultaneously. And difficult consider am-bipolar drift effect.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.223.2-223.2
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• 2015

Polyurethane acrylate (PUA) has been introduced to utilize as a mold material for sub-100 nm lithography as it provides advantages of stiffness for nanostructure formation, short curing time, flexibility for large area replication and transparency for relevant biomedical applications. Due to the ability to fabricate nanostructures on PUA, there have been many efforts to mimic extracellular matrix (ECM) using PUA especially in a field of tissue engineering. It has been demonstrated that PUA is useful for investigating the nanoscale-topographical effects on cell behavior in vitro such as cell attachment, spreading on a substrate, proliferation, and stem cell fate with various types of nanostructures. In this study, we have conducted surface modification of PUA films with micro/nanostructures on their surfaces using plasma treatment. In general, it is widely known that the plasma treated surface increases cell attachment as well as adsorption of ECM materials such as fibronectin, collagen and gelatin. Effect of plasma treatment on PUA especially with surface of micro/nanostructures needs to be understood further for its biomedical applications. We have evaluated the modified PUA film as a culture platform using adipose derived stem cells. Then, the behavior of stem cells and the level of adsorbed protein have been analyzed.

• 한국전기전자재료학회논문지
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• 제24권2호
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• pp.89-94
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• 2011

The cause of the thickness non-uniformity in the large area deposition of $SiO_2$ films by PECVD(Plasma Enhanced Chemical Vapor Deposition) was investigated by the plasma diagnostics. The spatial distribution of the plasma species in the chamber was obtained with DLP(Double Langmuir Probe) and the new-designed probe-type QMS(Quadrupole Mass Spectrometer). From the relationship between the spatial distribution of the plasma species and the depositing rate of the $SiO_2$ films, it was conformed that the non-uniform deposition of $SiO_2$ films was related with the spatial distribution of the oxygen radical density and electron temperature.

• Nuclear Engineering and Technology
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• 제40권6호
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• pp.459-466
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• 2008

The KSTAR Magnet Power Supply (MPS) was dedicated to the SC coil commissioning and $1^{st}$ plasma experiment as a part of the system commissioning. Although many efforts to develop large-current power supplies that are useful for high power electronic devices have been made in various application fields, such as for large metal-plating devices, there were clear discrepancies between conventional power supply technologies and that for the SC coils due to the special SC coil load conditions. Therefore, most of the power supply technologies for the SC coils were a challenge in the domestic research area due to their limited application. However, the MPS commissioning result showed that all of the hardware and controlling software operated well, and this result finally led to the success of SC coil commissioning and the KSTAR $1^{st}$ plasma experiment. This paper will describe key features of KSTAR MPS for the $1^{st}$ plasma experiment, and will also report the commissioning results of the magnet power supplies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.277.1-277.1
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• 2016

We report on synthesis of large-area MoS2 using chemical vapor deposition (CVD). Relatively uniform MoS2 are obtained. To fabricate field-effect transistor (FET) devices, MoS2 films are transferred to another SiO2/Si substrate using polystyrene (PS) and patterned using oxygen plasma. In addition, to reduce contact resistance, synthesis of graphene used as channel. Device characteristics are presented and compared with the reported results.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권11호
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• pp.496-500
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to significantly impact terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (RIE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi-Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7% efficiency of mono-crystalline silicon solar cell and 10.2% multi-crystalline silicon solar cell.

• 지질공학
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• 제31권3호
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• pp.433-445
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• 2021

고전압 아크 방전에 의한 플라즈마 발파의 유체 침투 효율을 검증하기 위해 실험실 규모의 토사 시료에 대하여 발파 시험을 실시하였다. 이 연구를 위해 대용량 축전기가 포함된 플라즈마 발파 장치와 직경 80 cm, 높이 60 cm 크기의 컬럼형 토사 시료를 제작하였다. 토사 시료로는 사질토와 실트를 7:3 비율로 섞은 A 시료 7개와 9:1 비율로 섞은 B 시료 3개가 제작되었다. A 시료에 플라즈마 발파 없이 수압만으로 유체를 주입했을 때는 시추공 주변으로 국소적인 침투만 발생되었고 침투면적비는 5% 이하로 분석되었다. 플라즈마 발파에 의한 유체 침투 시험은 1 kJ, 4 kJ 그리고 9 kJ의 방전 에너지로 실시되었다. A 시료에 대한 플라즈마 발파 시험에서 유체의 침투면적비는 1회만 발파하였을 때는 16~25%이고 5회 연속 발파 시에는 30~48%로 분석되어, 수압만으로 유체를 주입했을 때보다 침투면적이 최대 9.6배까지 넓어졌다. B 시료에 대한 5회 연속 플라즈마 발파 시험에서 유체의 침투면적비는 33~59%로 분석되어 동일 조건의 A 시료 시험에 비해 침투면적이 1.1~1.4배 정도 넓어졌다. 이러한 결과는 플라즈마 발파 시에 방전 에너지가 클수록, 발파 횟수가 증가할 수록 유체의 침투면적이 증가하며, 투수성이 큰 토양에서 플라즈마 발파가 더욱 효과적임을 보여준다. 유체 침투 효과를 삼차원적인 부피로 분석하기 위해 유체 침투반경을 계산하였다. 수압으로만 유체를 주입했을 때의 침투반경은 9 cm인 반면에, 9 kJ의 에너지로 5회 발파 시에는 침투반경이 27~30 cm로 계산되어 유체 침투 효과가 최대 333%까지 증가되었다. 이러한 연구결과는 투수성이 낮은 실제 오염토양에서 원위치 토양 세정을 실시할 때 플라즈마 발파 기술을 적용하면, 세정제의 전달범위가 증가되어 정화효율이 개선될 수 있다는 것을 보여준다.