• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1111-1113
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• 2004

n+ etching process is investigated in the fabrication of TFF-LCD using low resistance data line of Mo/Al/Mo. Problems of consumption of upper Mo layer and contamination of channel area are resolved. Either of HCl or $Cl_2$ can be selected as a main etchant gas, and either of $SF_6$ or $CF_4$ can be selected as an additive. Plasma treatment after n+ etching process can reduce the off-current high problem.

• Transactions on Electrical and Electronic Materials
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• v.9 no.4
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• pp.156-162
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• 2008

We report results on a study of inductively coupled plasma (ICP) etching of Parylene-C (poly-monochloro-para-xylylene) films using an $O_2$ gas. Effects of process parameters on etch rates were investigated and are discussed in this article from the standpoint of plasma parameter measurements, performed using a Langmuir probe and modeling calculation. Process parameters of interest include ICP source power and pressure. It was shown that major etching agent of polymer films was oxygen atoms O($^3P$). At the same time it was proposed that positive ions were not effective etchant, but ions played an important role as effective channel of energy transfer from plasma towards the polymer.

• Nuclear Engineering and Technology
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• v.35 no.6
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• pp.507-514
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• 2003

Recently dry decontamination/surface-cleaning technology using plasma etching has been focused in the nuclear industry. In this study, the applicability of this new dry processing technique are experimentally investigated by examining the etching reaction of $UO_2$, Co, and Mo in r.f. plasma with the etchant gas of $CF_4/O_2$ mixture. $UO_2$ is chosen as a representing material for uranium and TRU (TRans-Uranic) compounds while metallic Co and Mo are selected because they are the principal contaminants in the used metallic nuclear components such as valves and pipes made of stainless steel or inconel. Results show that in all cases maximum etching rate is achieved when the mole fraction of $UO_2\;in\;CF_4/O_2$ mixture gas is $20\%$, regardless of temperature and r.f. power. In case of $UO_2$, the highest etching reaction rate is greater than 1000 monolayers/min. at $370^{\circ}C$ under 150 W r.f. power which is equivalent to $0.4{\mu}m/min$. As for Co, etching reaction begins to take place significantly when the temperature exceeds $350^{\circ}C$. Maximum etching rate achieved at $380^{\circ}C\;is\;0.06{\mu}m/min$. Mo etching reaction takes place vigorously even at relatively low temperature and the reaction rate increases drastically with increasing temperature. Highest etching rate at $380^{\circ}C\;is\;1.9{\mu}m/min$. According to OES (Optical Emission Spectroscopy) and AES (Auger Electron Spectroscopy) analysis, primary reaction seems to be a fluorination reaction, but carbonyl compound formation reaction may assist the dominant reaction, especially in case of Co and Mo. Through this basic study, the feasibility and the applicability of plasma decontamination technique are demonstrated.

• Journal of the Korean Vacuum Society
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• v.17 no.2
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• pp.113-116
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• 2008

As the integration in semiconductor display develops, semiconductor process becomes multilayer. In order to form several layer patterns, etching process which uses photoresistor (PR) must be performed in multilayer process. Repeated etching processes which take long time and PR residue cause mortal problems in semiconductor. To overcome such problems, we studied about the solution which eliminates PR effectively by using normal dry and wet etching method using plasma activated PR strip solvent in liquid condition. At first, we simulate the device which activates the plasma and make sure whether gas flow in device is uniform or not. Under activated plasma, etching effect is elevated. This improvement reduces etching time as well as display production time of semiconductor process. Generally, increasing etching process increases environmental hazards. Reducing etching process can save the etchant and protect environment as well.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.57-66
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• 1988

A series of experiments is performed to measure radon concentration in the near-surface soil gas at the four locations (Cheju-Si, Seoguipo-Si, Taejeong-eup, Seongsan-eup) in Cheju Island, using CR-39 detectors placed inside radon cups. Two types of radon cups are installed in shallow holes of about 15 cm in diameter and 50cm in depth. The optimum etching conditions, i.e., the concentration of NaOH solution, etchant temperature and etching time, are found to be 625N, $70^{\circ}C$ and 5.5 hours for CR-39 detectors. A typical conversion factor of radon cup is calculated as $$1track/mm^3{\cdot}30day=0.059Bq/{\ell}$$. Average radon concentrations over 30 days measured in Cheju Island from May 1, 1987 to April 23, 1988 are $3.1{\pm}0.3Bq/{\ell}$ for open radon cups and $1.7{\pm}0.2Bq/{\ell}$ for closed radon cups.

• Journal of Sensor Science and Technology
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• v.22 no.4
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• pp.244-248
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• 2013

The discovery of a two-dimensional electron gas (2DEG) in $LaAlO_3$ (LAO)/$SrTiO_3$ (STO) heterostructure has stimulated intense research activity. We suggest a new structure model based on $KNbO_3$ (KNO) material. The KNO thin films were grown on $TiO_2$-terminated STO substrates as a p-type structure ($NbO_2/KO/TiO_2$) to form a two-dimensional hole gas (2DHG). The STO thin films were grown on KNO/$TiO_2$-terminated STO substrates as an n-type structure to form a 2DEG. Oxygen pressure during the deposition of the KNO and STO thin films was changed so as to determine the effect of oxygen vacancies on 2DEGs. Our results showed conducting behavior in the n-type structure and insulating properties in the p-type structure. When both the KNO and STO thin films were deposited on a $TiO_2$-terminated STO substrate at a low oxygen pressure, the conductivity was found to be higher than that at higher oxygen pressures. Furthermore, the heterostructure formed at various oxygen pressures resulted in structures with different current values. An STO/KNO heterostructure was also grown on the STO substrate, without using the buffered oxide etchant (BOE) treatment, so as to confirm the effects of the polar catastrophe mechanism. An STO/KNO heterostructure grown on an STO substrate without BOE treatment did not exhibit conductivity. Therefore, we expect that the mechanics of 2DEGs in the STO/KNO heterostructures are governed by the oxygen vacancy mechanism and the polar catastrophe mechanism.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.109.2-109.2
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• 2015

Graphene, as a single layer of $sp^2$-bonded carbon atoms packed into a 2D honeycomb crystal lattice, has attracted much attention due to its outstanding properties such as high carrier mobility, chemical stability, and optical transparency. In order to synthesize high quality graphene, transition metals, such as nickel and copper, have been widely employed as catalysts, which need transfer to desired substrates for various applications. However, the transfer steps inevitably induce defects, impurities, wrinkles, and cracks of graphene. Here, we report a facile transfer-free graphene synthesis method through nickel and carbon co-deposited layer, which does not require separately deposited catalytic nickel and carbon source layers. The 100 nm NiC layer was deposited on the top of $SiO_2/Si$ substrates by nickel and carbon co-deposition. When the sample was annealed at $1000^{\circ}C$, the carbon atoms diffused through the NiC layer and deposited on both sides of the layer to form graphene upon cooling. The remained NiC layer was removed by using nickel etchant, and graphene was then directly obtained on $SiO_2/Si$ without any transfer process. Raman spectroscopy was carried out to confirm the quality of resulted graphene layer. Raman spectra revealed that the resulted graphene was at high quality with low degree of $sp^3$-type structural defects. Furthermore, the Raman analysis results also demonstrated that gas flow ratio (Ar : $CH_4$) during the NiC deposition and annealing temperature significantly influence not only the number of graphene layers but also structural defects. This facile non-transfer process would consequently facilitate the future graphene research and industrial applications.

• Korean Journal of Materials Research
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• v.2 no.6
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• pp.428-435
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• 1992

AISI 4600 Iron powder was mixed with 0~1.0% phosphor as F$e_2$P powder and/or 0~0.8% carbon as graphite powder in rotating mixer. Mixed powder was pressed 800MPa in double-punch mould. Compacts were sintered at 115$0^{\circ}C$for 30 min. in vacuum or mixed hydrogen and nitrogen gas. Sintered compacts were ground and polished, and etched by 2% nital etchant. The microstructure was observed by image analyzer and optical microscope. Density and microhardness were tested by ASTM B3l2 and Microvickers hardness tester. The results obtained were as follows : (1) As the amount of F$e_2$P powder increased, sintered microstructure showed more densified effect and the grain size was larger. (2) The shape of pore was rounded and the number of pore was decreased by F$e_2$P addition. But mean pore size was larger with F$e_2$P content. (3) Simultaneous alloying addition of F$e_2$P and graphite brought about larger grain growth than respective addition. (4) Sintering atmosphere did not affect the microstructure. (5) Hardness of sintered compact increased with phosphrous and carbon content.