• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권8호
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• pp.438-444
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• 2000

We report the effects of etch process parameters on the ohmic contact formation in the plasma etching of GaN. Planar inductively coupled plasma system with $CH_4/H_2/Ar$gas chemistry has been used as etch reactor. The contact resistance and the specific contact resistance have been investigated using transfer length method as a function of RF bias power and %Ar gas concentration in total flow rate. AES(Auger electron spectroscopy) analysis revealed that the etched GaN has nonstoichiometric Ga rich surface and was contaminated by carbon and oxygen. Especially large amount of carbon was detected at the sample etched for high bias power (or voltage) condition, where severe degradation of contact resistance was occurred. We achieved the low ohmic contact of $2.4{\times}10^{-3} {\Omega}cm^2$ specific contact resistance at the input power 400 W, RF bias power 150 W, and working pressure 10mTorr with 10 sccm $CH_4$, 15 sccm H2, 5 sccm Ar gas composition.

• 한국표면공학회지
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• 제38권5호
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• pp.202-206
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• 2005

Nitriding treatments were conducted on tool steel (SKD 61) at a temperature of $500^{\circ}C$ for 5 hr using high vacuum direct current (DC) plasma, with ammonia and argon as source gases. The structural and compositional changes produced in the nitrided layers by applying different ratios of Ar to $NH_{3}\;(n_{Ar}/n_{NH3}) were investigated using glancing x-ray diffraction (GXRD), optical microscopy, atomic force microscopy (AFM), micro-Vickers hardness testing, and pin-on-disc type tribometer. Nitriding case depths of around of $50{\mu}m$ were produced, varying slightly with different ratios of $n_{Ar}/n_{NH3}. It was found that the specimen surface hardness was 1150 Hv with $n_{Ar}/n_{NH3}=1, increasing to a maximum value of 1500 Hv with $n_{Ar}/n_{NH3}=5. With a further increase in ratio to $n_{Ar}/n_{NH3}=10, the surface hardness of the specimen reduced slightly to a value of 1370 Hv. These phenomena were caused by changes of the crystallographic structure of the nitride layers, i.e the $\gamma'-Fe_{4}N$ phase only was observed in the sample treated with $n_{Ar}/n_{NH3}$=1, and the intensity of the $\gamma'-Fe_{4}N$ phase were reduced but new phase of $\varepsilon'-Fe_{3}N$, which was known as a high hardness, with increasing $n_{Ar}/n_{NH3}. Also, the relative weight loss of counterface of the pin-on-disc with unnitrided steel was 0.2. And that of nitrided steel at a gas mixture ($n_{Ar}/n_{NH3}) of 1, 5, 7, and 10 was 0.4, 0.7, 0.6, and 0.5 mg, respectively. This means that the wear resistance of the nitrided samples could be increased by a factor of 2 at least than that of unnitrided steel.

• Transactions on Electrical and Electronic Materials
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• 제12권4호
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• pp.144-147
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• 2011

In this work, we present a study regarding the etching characteristics on titanium nitride (TiN) thin films using an inductively coupled plasma system. The TiN thin film was etched using a $N_2/BCl_3$/Ar plasma. The studied etching parameters were the gas mixing ratio, the radio frequency (RF) power, the direct current (DC)-bias voltages, and the process pressures. The baseline conditions were as follows: RF power = 500 W, DC-bias voltage = -150 V, substrate temperature = $40^{\circ}C$, and process pressure = 15 mTorr. The maximum etch rate and the selectivity of the TiN to the $SiO_2$ thin film were 62.38 nm/min and 5.7, respectively. The X-ray photoelectron spectroscopy results showed no accumulation of etching byproducts from the etched surface of the TiN thin film. Based on the experimental results, the etched TiN thin film was obtained by the chemical etching found in the reactive ion etching mechanism.

• 대한금속재료학회지
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• 제46권3호
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• pp.125-130
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• 2008

Conventional plasma carburizing or nitriding for austenitic stainless steels results in a degradation of corrosion resistance. However, a low temperature plasma surface treatment can improve surface hardness without deteriorating the corrosion resistance. The 2-step low temperature plasma processes (the combined carburizing and post nitriding) offers the increase of both surface hardness and thickness of hardened layer and corrosion resistance than the individually processed low temperature nitriding and low temperature carburizing techniques. In the present paper, attempts have been made to investigate the influence of the introduction of Ar gas (0~20%) in nitriding atmosphere during low temperature plasma nitriding at $370^{\circ}C$ after low temperature plasma carburizing at $470^{\circ}C$. All treated specimens exhibited the increase of the surface hardness with increasing Ar level in the atmosphere and the surface hardness value reached up to 1050 HV0.1, greater than 750 $HV_{0.1}$ in the carburized state. The expanded austenite phase (${\gamma}_N$) was observed on the most of the treated surfaces. The thickness of the ${\gamma}_N$ layer reached about $7{\mu}m$ for the specimen treated in the nitriding atmosphere containing 20% Ar. In case of 10% Ar containing atmosphere, the corrosion resistance was significantly enhanced than untreated austenitic stainless steels, whilst 20% Ar level in the atmosphere caused to form CrN in the N-enriched layer (${\gamma}_N$), which led to the degradation of corrosion resistance compared with untreated austenitic stainless steels.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.468-470
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• 1999

One of the most critical problem in etching of platinum was generally known that the etch slope was gradual. therefore, the addition of $N_2$ gas into the Ar/C1$_2$ gas mixture, which has been proposed the optimized etching gas combination for etching of platinum in our previous article, was performed. The selectivity of platinum film to oxide film as an etch mask increased with the addition of N2 gas, and the steeper etch slope over 75 $^{\circ}$ could be obtained. These phenomena were interpreted the results the results of a blocking layer such as Si-N or Si-O-N on the oxide mask. Compostional analysis was carried out by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). Moreover, it could be obtained the higher etch rate of Pt film and steeper profile without residues such as p.-Cl and Pt-Pt ant the addition N\ulcorner of 20 % gas in Ar(90)/Cl$_2$(10) Plasma. The Plasma characteristic was extracted from optical emissionspectroscopy (OES).

• 전기의세계
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• 제27권3호
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• pp.36-42
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• 1978

It has been investigates that electric characteristics of plasma electron beam in N$_{2}$, H$_{2}$ and Ar gas jars under various gas pressures during electron beams are formed. The results are as follows: 1)Electron beam is formed in the region of positive resistance on the characteristic curve. This phenomenon is identical in N$_{2}$, H$_{2}$ and Ar gases. 2)But in Ar gas, electron beam is formed at relatively lower gas pressure than in H$_{2}$ and N$_{2}$. 3)In pure gas either N$_{2}$, H$_{2}$ and N$_{2}$ the lower the gas pressure, the higher the voltage drop for the same electron beam current. 4)The region in which electron beam is formed is limited at a given pressure. 5)Beyond the limit mentioned above, it becomes glow discharge state and the current increases radically. 6)At a given gas pressure, electron beam voltage, that is, electrical power input increases with gap length.

• 한국전기전자재료학회논문지
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• 제21권12호
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• pp.1051-1056
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• 2008

In this study, the investigations of the TiN etching characteristics were carried out with addition of $Cl_2$ gas in an inductively coupled $BCl_3$-base plasma system. Dry etching of the TiN was studied by varying the etching parameters including $Cl_2$ gas addition ratio, RF power, DC-bias voltage and pressure. The etch rate of TiN thin film was maximum when the $Cl_2$ gas addition flow was 2 sccm with fixed other conditions. As the RF power DC-bias voltage were increased, the etch rate of TiN thin film showed increasing tendency. $BCl_3/Cl_2$/Ar plasmas were characterized by optical emission spectroscopy (OES) analysis. The chemical reaction on the surface of the etched TiN films was investigated with X-ray photoelectron spectroscopy (XPS).

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 1999년도 추계학술발표회 초록집
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• pp.59-59
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• 1999

In this study, planer inductively coupled $Cl_2$ based plasmas were used to etch InGaN and the effects of plasma conditions on the InGaN etch properties have been characterized using quadrupole mass spectrometry(QMS) and optical emission spectroscopy(OES). As process conditions used to study the effects of plasma characteristics on the InGaN etch properties, $Cl_2$ was used as the main etch gas and $CHF_3,{\;}CH_4$, and Ar were used as additive gases. Operational pressure was varied from SmTorr to 3OmTorr, inductive power and bias voltage were varied from 400W to 800W and -50V to -250V, respectively while the substrate temperature was fixed at 50 centigrade. For the $Cl_2$ plasmas, selective etching of GaN to InGaN was obtained regardless of plasma conditions. The small addition of $CHF_3$ or Ar to $Cl_2$ and the decrease of pressure generally increased InGaN etch rates. The selective etching of InGaN to GaN could be obtained by the reduction of pressure to l5mTorr in $CI_2/IO%CHF_3{\;}or{\;}CI_2/IO%Ar$ plasma. The enhancement of InGaN etch rates was related to the ion bombardment for $CI_2/Ar$ plasmas and the formation of $CH_x$ radicals for $CI_2/CHF_3(CH_4)$ plasmas.

• Mass Spectrometry Letters
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• 제10권1호
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• pp.27-31
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• 2019

In this article, the properties of ${CO_2}^+(CO_2)_n$ clusters in a Paul ion trap have been investigated using mass-selective instability mode which conducted by chosen precursor ions, mainly $Ar^+$ and ${CO_2}^+$ produced by a mixture of Ar and $CO_2$. Exposure of ${CO_2}^+$ ions to $CO_2$ molecules, lead to the formation of ${CO_2}^+(CO_2)_n$ clusters. Here, Ar gas react as a buffer gas and lead to form ${CO_2}^+(CO_2)_n$ cluster by collisional effect.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.247-248
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• 2008

The etching characteristics of Titanium Nitride (TiN) and etch selectivity of TiN to $SiO_2$ and $HfO_2$ in $CH_4$/Ar plasma were investigated. It was found that TiN etch rate shows a non-monotonic behavior with increasing both Ar fraction in $CH_4$ plasma, RF power, and gas pressure. The maximum TiN etch rate of nm/min was obtained for $CH_4$ (80%)/Ar(20%) gas mixture. The plasmas were characterized using optical emission spectroscopy (OES) analysis measurements. From these data, the suggestions on the TiN etch characteristics were made.