• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.357-362
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• 1996

Several applications of radio-frequency (RF) thermal plasma to film formation are reviewed. Three types of injection plasma processing (IPP) technique are first introduced for the deposition of materials. Those are thermal plasma chemical vapor deposition (CVD), plasma flash evaporation, and plasma spraying. Radio-frequency (RF) plasma and hybrid (combination of RF and direct current(DC)) plasma are next introduced as promising thermal plasma sources in the IPP technique. Experimental data for three kinds of processing are demonstrated mainly based on our recent researches of depositions of functional materials, such as high temperature semiconductor SiC and diamond, ionic conductor $ZrO_2-Y_2O_3$ and high critical temperature superconductor $YBa_2Cu_3O_7-x$. Special emphasis is given to thermal plasma flash evaporation, in which nanometer-scaled clusters generated in plasma flame play important roles as nanometer-scaled clusters as deposition species. A novel epitaxial growth mechanism from the "hot" clusters namely "hot cluster epitaxy (HCE)" is proposed.)" is proposed.osed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.406-407
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• 2006

This paper describes the ohmic contact formation between a TiW film as a contact material deposied by RF magnetron sputter and polycrystalline 3C-SiC films deposied on thermally grown Si wafers. The specific contact resistance (${\rho}_c$) of the TiW contact was measured by using the C-TLM. The contact phase and interfacial reaction between TiW and 3C-SiC at high-temperature were also analyzed by XRD and SEM. All of the samples didn't show cracks of the TiW film and any interfacial reaction after annealing. Especially, when the sample was annealed at $800^{\circ}$ for 30min., the lowest contact resistivity of $2.90{\times}10^{-5}{\Omega}cm^2$ was obtained due to the improved interfacial adhesion.

• Journal of Photoscience
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• v.9 no.3
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• pp.57-63
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• 2002

A homopolymer containing anthracene groups, poly[6-(9-anthryloxy)hexyl methacrylate] (PAn) was prepared and the effect of oxygen on its photochemical reaction was studied by UV and IR absorption spectroscopy in order to understand its photochemical behavior. Photochemical reaction of the PAn in THF solution under an atmosphere of air resulted in the formation of endoperoxide at the beginning stage of reaction followed by photodimerization reaction after all the oxygen was consumed, whereas photodimerization and endoperoxide formation took place concomitantly in the film state. The photoreversible reaction of the anthracene photodimer groups in the polymer by photolysis with 254 nm UV light was not efficient. The IR absorption spectral changes of the PAn film upon irradiation indicate that various photooxidation products were produced in the atmosphere of air.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.8
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• pp.387-391
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• 2006

The Ag photodoping effect in amorphous $As_{40}Ge_{10}Se_{15}S_{35}$ chalcogenide thin films for holographic recording has been investigated using a He-Ne laser (${\lambda}$=632.8 nm). The chalcogenide films thickness prepared in the present work were thinner in comparison with the penetration depth of recording light ($d_p=1.66{\mu}m$). It exhibits a tendency of the variation of the diffraction efficiency (${\eta}$) in amorphous chalcogende films, independently of the Ag photodoping. That is, ${\eta}$ increases rapidly at the beginning of the recording process and reaches the maximum (${\eta}_{max}$) and slowly decreases slowly with the exposed time. In addition, the value of ${\eta}_{max}$ depends strongly on chalcogenide film thickness(d) and its maximum peak among the films with d = 40, 80, 150, 300, and 633 nm is observed 0.083% at d = 150 nm (approximately 1/2 ${\Delta}n$), where ${\Delta}$n is the refractive index of chalcogenide thin film (${\Delta}n=2.0$). The ${\eta}$ is largely enhanced by Ag photodoping into the chakogenides. In particular, the value of ${\eta}_{max}$ in a bilayer of 10-nm-thick Ag/150-nm-thick $As_{40}Ge_{10}Se_{15}S_{35}$ film is about 1.6%, which corresponds to ${\sim}20$ times larger than that of the single-layer $As_{40}Ge_{10}Se_{15}S_{35}$ thin film (without Ag). And we obtained the diffraction pattern according to the formation of (P:P) polarization holographic grating using Mask pattern and SLM.

• Journal of the Korean Vacuum Society
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• v.8 no.3B
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• pp.262-268
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• 1999

Polycarbonate (PC) and Polymethylmethacrylate (PMMA) surface was modified by ion assisted reaction (IAR) technique to obtain the hydrophilic functional groups and improve the wettability. In conditions of ion assisted reaction, ion beam energy was changed from 500 to 1500eV, and ion dose and oxygen gas blown rate were fixed $1\times10^{16}$ ions/$\textrm{cm}^2$ and 4ml/min, respectively. Wetting angle of water on PC and PMMA surface modified by $Ar^+$ ion without blowing oxygen at 4ml/mon showed $5^{\circ}$ and $10^{\circ}$. Changes of wetting angle with oxygen gas and $Ar^+$ ion irradiation were explained by considering formation of hydrophilic group due to a reaction between irradiated polymer chain by energetic ion irradiation and blown oxygen gas. X-ray photoelectron spectroscopy analysis shows that hydrophilic groups such as -C-O, -(C=O)- and -(C=O)-O- are formed on the surface of polymer by chemical interaction. The polymer surface modification using ion assisted reaction only changed the surface physical properties and sept the bulk properties. In comparison with other modification methods, the surface modification by IAR treatment was chemically stable and enhanced the adhesion between metal and polymer surface. The applications of various kinds of polymer surface modification methods, metal and polymer surface. The applications of various kinds of polymer surface modification could be appled to the new materials about hydrophilic surface properties by IAR treatment. The adhesion between metal film and polymer measured by Scotch tape test whether the hydrophilic surfaces could improve the adhesion strength or not.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.144-149
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• 2000

Variables affecting the passivation capability of Cu(Mg) alloy films, which were sputter deposited from a Cu (4.5 at. %) target, have been investigated. The results show that the passivation capability of a Cu(Mg) alloy film is a function of annealing temperature, $O_2$ pressure, and Mg content in the film. Increasing the annealing temperature up to $500^{\circ}C$ favors formation of a dense MgO layer on the surface which has a growth limited thickness of 150 $\AA$. Decreasing the $O_2$ pressure enhances the preferential oxidation of Mg over Cu. Furthermore, increasing the Mg content in the Cu(Mg) film promotes formation of a dense MgO layer. Vacuum pre-annealing was found to be very effective in segregating Mg to the surface, facilitating the passivation capability of the Cu(Mg) alloy film even when the Mg content is low. In the current study, self-aligned MgO layers with low resistivity and an effective passivation capability over the Cu surface, have been obtained by manipulating these factors when Cu(Mg) thin films are annealed.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.21-28
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• 2004

We have demonstrated the applicability of dry film photoresist (DFR) in photolithography process for fine pitch solder bumping on the polytetrafluoroethylene (PTFE/Teflon ) printed circuit board (PCB). The copper lines were formed with 100$\mu\textrm{m}$ width and 18$\mu\textrm{m}$ thickness on the PTFE test board, and varying the gaps between two copper lines in a range of 100-200$\mu\textrm{m}$. The DFRs of 15$\mu\textrm{m}$ thickness were laminated by hot roll laminator, by varying laminating temperature from $100{\circ}C$ to 15$0^{\circ}C$ and laminating speed from 0.28-0.98cm/s. We have found the optimum process of DFR lamination on PTFE PCB and accomplished the formation of indium solder bumps. The optimum lamination condition was temperature of $150^{\circ}C$ and speed of about 0.63cm/s. And the smallest size of indium solder bump was diameter of 50$\mu\textrm{m}$ with pitch of 100$\mu\textrm{m}$.

• Corrosion Science and Technology
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• v.16 no.6
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• pp.317-327
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• 2017

The change in the oxidation behavior of three types of B-added ultrahigh strength martensitic steels containing Ti and Nb induced by applying constant cathodic current was investigated. In a 3% NaCl+0.3% $NH_4SCN$ solution, the overall polarization behavior of the three alloys was similar, and degradation of the oxide film was observed in the three alloys after applying constant cathodic current. A significant increase in the anodic current density was observed in the Nb-added alloy, while it was diminished in the Ti-added alloy. Both Ti and Nb alloying decreased the hydrogen overpotential by forming NbC and TiC particles. In addition, the thickest oxide film was formed on the Ti-added alloy, but the addition of Nb decreased the film thickness. Therefore, it was concluded that the remarkable increase in the anodic current density of Nb-added alloy induced by applying constant cathodic current density was attributed to the formation of the thinnest oxide film less protective to hydrogen absorption, and the addition of Ti effectively blocked the hydrogen absorption by forming TiC particles and a relatively thick oxide film.

• Journal of the Korean institute of surface engineering
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• v.52 no.5
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• pp.246-250
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• 2019

Nano-multilayered $Cr_{25.2}Al_{19.5}Si_{4.7}N_{50.5}$ films were deposited on the steel substrate by cathodic arc plasma deposition. They were corroded at $900^{\circ}C$ in $Ar/1%SO_2$ gas in order to study their corrosion behavior in sulfidizing/oxidizing environments. Despite the presence of sulfur in the gaseous environment, the corrosion was governed by oxidation, leading to formation of protective oxides such as $Cr_2O_3$ and ${\alpha}-Al_2O_3$, where Si was dissolved. Iron diffused outward from the substrate to the film surface, and oxidized to $Fe_2O_3$ and $Fe_3O_4$. The films were corrosion-resistant up to 150 h owing to the formation of thin ($Cr_2O_3$ and/or ${\alpha}-Al_2O_3$)-rich oxide layers. However, they failed when corroded at $900^{\circ}C$ for 300 h, resulting in the formation of layered oxide scales due to not only outward diffusion of Cr, Al, Si, Fe and N, but also inward movement of sulfur and oxygen.

• Korean Journal of Materials Research
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• v.33 no.7
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• pp.309-314
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• 2023

This study aimed to address the limitations of traditional plasma nitriding methods by implementing a short-term plasma oxy-nitriding treatment on the surface of AISI 420 martensitic stainless steel. This treatment involved the sequential formation of nitride and oxide layers, to enhance surface hardness and corrosion resistance, respectively. The process resulted in the formation of a 20 ㎛-thick nitride layer and a 3 ㎛-thick oxide layer on the steel surface. Initially, the hardness increased by 2.2 times after nitriding, followed by a subsequent decrease of approximately 31 % after oxidation. While the nitriding process reduced corrosion resistance, the subsequent oxidation process led to the formation of a passive oxide film, effectively resolving this issue. The pitting corrosion of the oxide passive film started at 82.6 mVssc, providing better corrosion resistance characteristics than the nitride layer. Consequently, the trade-off between surface hardness and corrosion resistance in plasma oxy-nitrided AISI 420 martensitic stainless steel is anticipated to be recognized as an innovative and comprehensive surface treatment process for biomedical components.