• Journal of the Korean Society for Heat Treatment
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• 제24권1호
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• pp.3-9
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• 2011

Plasma nitriding of stainless steels has been investigated over a range of temperature from 400 to $500^{\circ}C$ and time from 10 to 20 hours. Characterization of systematic materials was carried out in terms of mechanical properties and corrosion behaviors. The results showed that plasma nitriding conducted at low temperatures not only increased the surface hardness, but also improved the corrosion resistance of STS 316L, STS409L, and STS 420J2. It was found that plasma-nitriding treatment at $500^{\circ}C$ resulted in increasing the corrosion performance of STS 409L and STS 420J2, while STS 316L was observed with server and massive damage on surface due to the formation of CrN.

• Journal of the Korean institute of surface engineering
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• 제50권4호
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• pp.272-276
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• 2017

The response of AISI 310 type austenitic stainless steel to the novel low temperature plasma carburizing process has been investigated in this work. This grade of stainless steel shows better corrosion resistance and high temperature oxidation resistance due to its high chromium and nickel content. In this experiment, plasma carburizing was performed on AISI 310 stainless steel in a D.C. pulsed plasma ion nitriding system at different temperatures in $H_2-Ar-CH_4$ gas mixtures. The working pressure was 4 Torr (533Pa approx.) and the applied voltage was 600 V during the plasma carburizing treatment. The hardness of the samples was measured by using a Vickers micro hardness tester with the load of 100 g. The phase of carburized layer formed on the surface was confirmed by X-ray diffraction. The resultant carburized layer was found to be precipitation free and resulted in significantly improved hardness and corrosion resistance.

• Journal of the Korean institute of surface engineering
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• 제40권5호
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• pp.209-213
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• 2007

Change of the plasma volume by pulse frequency in a bipolar pulsed DC unbalanced magnetron sputtering was investigated. As increasing the frequency at off duty 10% and at a constant power, the plasma volume was lengthened in vertical direction from the AZO target. When there is an electrically floated substrate, the vertical length of the plasma area was not affected by the pulse frequency. Instead, the diameter of the plasma volume was increased. We found that the temperature rise of a substrate was affected by the pulse frequency, too. As increasing it, the maximum temperature rise of a glass substrate was decreased from $132^{\circ}C\;to\;108^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• 제51권9호
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• pp.413-416
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• 2002

It was reported that low temperature plasma developed by our group was apparently homogeneous and stable at atmospheric pressure, and was generated if the alumina was used as a dielectric insulating material and Ar gas as a plasma gas. This is a structure in which the dielectric materials are covered and arranged in parallel in the one side of electrode. In this experiment, we discovered that dielectric material was important to generate normal electric discharge. To examine the effect of dielectric material on the electric discharge characteristic, the voltage and current of the plasma was measured and the electrical effect of dielectric material was examined. Also, it was applied to an etching of tin oxide films.

• Journal of the Korean institute of surface engineering
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• 제50권6호
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• pp.504-509
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• 2017

In order to improve corrosion resistance for cast stainless steel in seawater, the characteristics of corrosion resistance after plasma ion nitriding was investigated. Plasma ion nitriding process was conducted in a mixture of nitrogen of 25% and hydrogen of 75% at substrate temperature ranging from 350 to $500^{\circ}C$ for 10 hours using pulsed-DC glow discharge plasma with working pressure of 250 Pa in vacuum condition. Corrosion tests were carried out for as-received and plasma ion nitrided specimens. The corrosion characteristics were investigated by measurement of weight loss and observation of surface morphology. In anodic polarization experiment, relatively less damage depth and weight loss were presented at a nitrided temperature of $400^{\circ}C$, attributing to the formation of S-phase.

• Transactions on Control, Automation and Systems Engineering
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• 제2권4호
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• pp.268-273
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• 2000

Plasma models are crucial to equipment design and process optimization. A radial basis function network(RBFN) in con-junction with statistical experimental design has been used to model a process plasma. A 2$^4$ full factorial experiment was employed to characterized a hemispherical inductively coupled plasma(HICP) in characterizing HICP, the factors that were varied in the design include source power, pressure, position of shuck holder, and Cl$_2$ flow rate. Using a Langmuir probe, plasma attributes were collected, which include typical electron density, electron temperature. and plasma potential as well as their spatial uniformity. Root mean-squared prediction errors of RBEN are 0.409(10(sup)12/㎤), 0.277(eV), and 0.699(V), for electron density, electron temperature, and Plasma potential, respectively. For spatial uniformity data, they are 2.623(10(sup)12/㎤), 5.704(eV) and 3.481(V), for electron density, electron temperature, and plasma potential, respectively. Comparisons with generalized regression neural network(GRNN) revealed an improved prediction accuracy of RBFN as well as a comparable performance between GRNN and statistical response surface model. Both RBEN and GRNN, however, experienced difficulties in generalizing training data with smaller standard deviation.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.512-513
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• 2013

Space and time resolved discharge images from an atmospheric pressure non-thermal Ar plasma jet have been observed by a ICCD camera to investigate the electron temperatures. Plasma jet device consisting of a syringe electrode inserted into a glass tube has been introduced. A high voltage is applied to the syringe electrode. The syringe needle has an outer diameter of 1.8 mm, an inner diameter of 1.3 mm, and a total length of 39.0 mm. The needle is inserted into a glass tube of outer diameter 2.4 mm and inner diameter 2.0 mm, and a total length of 80.0 mm. The Ar plasma propagation speed on the cathode has been shown to be about 2.1 km/s at input discharge voltage of 3.6 kV, discharge current of 19.9 mA and driving frequency of about 45 kHz. Particularly, the electron temperature in plasma jet were found to be about 1.8 eV at input discharge voltage of 3.6 kV and driving frequency of 45 kHz, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제65권7호
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• pp.1211-1217
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• 2016

Discharge characteristics of inductively coupled plasma were investigated by using electrostatic probe and fluid simulation. The Inductively Coupled Plasma source driven by 13.56 Mhz was prepared. The signal attenuation ratios of the electrostatic probe at first and second harmonic frequency was tuned in 13.56Mhz and 27.12Mhz respectively. Electron temperature, electron density, plasma potential, electron energy distribution function and electron energy probability function were investigated by using the electrostatic probe. Experiment results were compared with the fluid simulation results. Ar plasma fluid simulations including Navier-Stokes equations were calculated under the same experiment conditions, and the dependencies of plasma parameters on process parameters were well agreed with simulation results. Because of the reason that the more collision happens in high pressure condition, plasma potential and electron temperature got lower as the pressure was higher and the input power was higher, but Electron density was higher under the same condition. Due to the same reason, the electron energy distribution was widening as the pressure was lower. And the electron density was higher, as close to the gas inlet place. It was found that gas flow field significantly affect to spatial distribution of electron density and temperature.

• Journal of the Semiconductor & Display Technology
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• 제18권2호
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• pp.98-102
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• 2019

Direct plasma-enhanced atomic layer deposition (PEALD) are widely used for $SiO_2$ and SiON thin film process in current semiconductor industry. However, this exhibits poor step coverage for three-dimensional device structure due directionality of plasma species as well as plasma damage on the substrate. In this study, to overcome this issue, low temperature (< $300^{\circ}C$) $SiO_2$ and SiON thin film processes were studied using inductively coupled plasma (ICP) type remote PEALD with various reactant gases such as $O_2$, $H_2O$, $N_2$ and $NH_3$. It was confirmed that the interfacial properties such as fixed charge density and charge trapping behavior of thin films were considerably improved by hydrogen species in $H_2O$ and $NH_3$ plasma compared to the films grown with $O_2$ and $N_2$ plasma. Furthermore, the leakage current density of the thin films was suppressed for same reason.

• Proceedings of the KSME Conference
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.612-617
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• 2001

This paper reports the cooling performance of a PDP(plasma display panel) with a heat spreader by means of numerical analysis. Due to the simplifications and assumptions inherent in the analysis, computed results are found to differ those of the experiment by 13%. Calculation shows a maximum temperature of $65^{\circ}C$ for the plasma glass, as opposed to the allowable temperature of $90^{\circ}C$, producing a temperature difference of $25^{\circ}C$ between the upper and lower regions. This is enough to cause cracks in the plasma glass. In order to avoid this, more ventholes are added at the upper center region of the back cover, thereby causing a $3^{\circ}C$ drop in the maximum temperature, which reduces the temperature difference to $12^{\circ}C$. The new design gives more uniform temperature distribution across the plasma glass.