• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1332-1336
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• 2004

Amorphous carbon (a-C) films have been deposited on Si(100) substrate using RF magnetron system in order to investigate the electron field emission properties. The a-C films were treated by $N_2$ gas plasma at room temperature. Surface morphologices and structural properties of the a-C films before and after $N_2$ plasma treatment were observed by scanning electron microscopy and Raman spectroscope, respectively. Structural properties and surface morphology of the a-C films were changed by $N_2$ plasma treatment. The emission properties can be improved by the plasma treatment according to the contents of nitrogen on the a-C films which is varied by plasma treatment time. Before the plasma treatment, the a-C films are found to have a threshold field of 14 V/$\mu$m, but the a-C film treated by $N_2$ plasma for 30 min exhibit threshold field as low as 6.5 V/$\mu$m.

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.84-90
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• 2005

The influence of plasma parameters on the growth of $In_{0.2}Ga_{0.8}N/GaN$ heterostructures has been investigated using plasma-assisted molecular beam epitaxy. Since plasma ejects plenty of energetic particles with different energy levels and flux density at various rf power levels, plasma modulated both growth rate and optical properties significantly. For instance, surface roughness and the emission spectrum of photoluminescence were degraded at low and high rf power. According to sharp interfaces between epitaxial films and strong peaks observed from photoluminescence spectra, our experimental setup presented optimal operation range of rf powers at around 400W. The phenomena could be explained by the presence of energetic particles modulating the rate of plasma stimulated desorption and surface diffusion, and energetic particles exceeding critical value resulted in the incorporation of defects at subsurface. The optimal rf power regime increased by 100W for $In_{0.2}Ga_{0.8}N/GaN$ growth in comparison with GaN. The effects of rf power were discussed in conjunction with kinetic processes being stimulated by energetic particles.

• Korean Journal of Materials Research
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• v.13 no.5
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• pp.338-342
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• 2003

Adhesion between Cu and low-k films has been investigated. Low-k films deposited using a mixture of hexamethyldisilane(HMDS) and Para-xylene had a dielectric constant as low as 2.7, showing the thermally stable properties up to $400^{\circ}C$. In this study, Ti glue layer, boron dopant, and $N_2$plasma treatment were used to improve adhesion property of between Cu and low-k films. Ti glue layer slightly improved adhesion property. After $N_2$plasma treatment, the adhesion property was significantly improved due to the increased roughness and the formation of new binding states between Ti and plasma-treated PPpX : HMDS. However, $300^{\circ}C$ annealing of $N_2$plasma treated sample caused the diffusion of Cu into the PPpX : HMDS, degrading the low-k properties. In the case of Cu(B)/Ti/PPpX : HMDS, the adhesion was remarkably increased. This enhanced adhesion was attributed to formation of Ti-boride at the Cu-Ti interface. It is because the formed Ti-boride prevented the diffusion of Cu into the PPpX : HMDS and the Cu-Ti reaction at the Ti interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.681-685
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• 2012

We investigated the dry etching characteristics of TiN in $TiN/Al_2O_3$ gate stack using a inductively coupled plasma system. TiN thin film is etched by BCl3/He plasma. The etching parameters are the gas mixing ratio, the RF power, the DC-bias voltages and process pressures. The highest etch rate is in $BCl_3/He$ (25%:75%) plasma. The selectivity of TiN thin film to $Al_2O_3$ is pretty similar with $BCl_3/He$ plasma. The chemical reactions of the etched TiN thin films are investigated by X-ray photoelectron spectroscopy. The intensities of the Ti 2p and the N 1s peaks are modified by $BCl_3$ plasma. Intensity and binding energy of Ti and N could be changed due to a chemical reaction on the surface of TiN thin films. Also we investigated that the non-volatile byproducts such as $TiCl_x$ formed by chemical reaction with Cl radicals on the surface of TiN thin films.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.75-81
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• 2018

The effect of $Ar-N_2$ plasma treatment on Cu surface as one of solutions to realize reliable Cu-Cu wafer bonding was investigated. Structural characteristic of $Ar-N_2$ plasma treated Cu surface were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscope. Ar gas was used for a plasma ignition and to activate Cu surface by ion bombardment, and $N_2$ gas was used to protect the Cu surface from contamination such as -O or -OH by forming a passivation layer. The Cu specimen under high Ar partial pressure plasma treatment showed more copper oxide due to the activation on Cu surface, while Cu surface after high $N_2$ gas partial pressure plasma treatment showed less copper oxide due to the formation of Cu-N or Cu-O-N passivation layer. It was confirmed that nitrogen plasma can prohibit Cu-O formation on Cu surface, but nitrogen partial pressure in the $Ar-N_2$ plasma should be optimized for the formation of nitrogen passivation layer on the entire surface of Cu wafer.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.78-79
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• 2007

In this study, chemical dry characteristics of silicon nitride layers were investigated in the $F_2/N_2/Ar$ remote plasma. A toroidal-type remote plasma source was used for the generation of remote plasmas. The effects of additive $N_2$ gas on the etch rates of various silicon nitride layers deposited using different deposition techniques and precursors were investigated by varying the various process parameters, such as the $F_2$ flow rate, the addition $N_2$ flow rate and the substrate temperature. The etch rates of the various silicon nitride layers at the room temperature were initially increased and then decreased with the $N_2$ flow increased, which indicates an existence of the maximum etch rates. The etch rates of the silicon oxide layers were also significantly increased with the substrate temperature increased. In the present experiments the $F_2$ gas flow, addition $N_2$ flow rate and the substrate temperature were found to be the critical parameters in determining the etch rate of the silicon nitride layers

• Membrane Journal
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• v.4 no.4
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• pp.205-212
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• 1994

Gas permeation properties of simple gases(He, $H_2,\;CO_2,\;O_2,\;N_2,\;CH_4$) through plasma-polymerized films were investigated, and the chemical structure of the plasma polymers was analyzed by infrared spectra. The plasma-polymerized films were prepared by plasma polymerization of fluorine-containing aromatic compounds, and permeation measurements were made at $35^{\circ}C$, latm. The permeability coefficient of the plasma films decreased as the size of penetrant molecules increased. The plasma polymers showed higher $CO_2/CH_4$ selectivities than those of commonly used polymers, while $O_2/N_2$ selectivities were similar of slightly lower than those of common polymers. FT-IR spectra shows that the plasma polymers contain both aromatic and aliphatic structures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.4
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• pp.65-70
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• 2011

Perfluorocompounds (PFCs) gases were decomposed by gliding arc plasma generated by AC pulse power. $N_2$ gas of 10 LPM flow rate and $H_2$ gas of 0.5 LPM were introduced into the gliding arc plasma generated between a pair of electrodes with SUS 303 material, and the PFCs gases were injected in the plasma and thereby were decomposed. The PFCs gas-decomposition-characteristics through the gliding arc plasma were analyzed by FT-IR, where pure $N_2$ and $H_2$-added $N_2$ environment were used to generate the gliding arc plasma. The PFCs gas-decomposition-properties were changed by electric power for gliding arc plasma generation and the H2 gas addition was effective to enhance the PFCs decomposition rate.

• Korean Journal of Materials Research
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• v.14 no.4
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• pp.265-269
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• 2004

Plasma nitrocarburising and post oxidation were performed on SCM435 steel by a pulsed plasma ion nitriding system. Plasma oxidation resulted in the formation of a very thin ferritic oxide layer 1-2 $\mu\textrm{m}$ thick on top of a 15～25 $\mu\textrm{m}$ $\varepsilon$-F $e_{2-3}$(N,C) nitrocarburized compound layer. The growth rate of oxide layer increased with the treatment temperature and time. However, the oxide layer was easily spalled from the compound layer either for both oxidation temperatures above $450^{\circ}C$, or for oxidation time more than 2 hrs at oxidation temperature $400^{\circ}C$. It was confirmed that the relative amount of $Fe_2$$O_3$, compared with $e_3$$O_4$, increased rapidly with the oxidation temperature. The amounts of ${\gamma}$'-$Fe_4$(N,C) and $\theta$-$Fe_3$C, generated from dissociation from $\varepsilon$-$Fe_{2-3}$ /(N,C) phase during $O_2$ plasma sputtering, were also increased with the oxidation temperature.e.

• Journal of Nutrition and Health
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• v.33 no.2
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• pp.167-178
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• 2000

The effect of oral vitamin e (800IU/day) and C (500mg/day) supplementation for 10 days and/or smoking cessation for 5 days on oxidative damage to the red blood cells (RBC) of male smokers (22.2$\pm$0.2 years old) was studied. RBC were tested for their ability to protect against smoking-induced oxidative damage by measuring heme proteins (carboxyhemoglobin, hemoglobin, methemoglobin, oxyhemoglobin), hemolysis and thiobarbiturinc acid reactive substances (TBARS). Plasma levels of vitamin c, A, E, $\beta$-catotene, total cholesterol, glutamic pyruvic transaminase(GPT) and glutamic oxaloacetic transaminase(GOT) were also analyzed. In experiment one, a comparison was made of heme proteins and lipid damage to RBC, plasma antioxidant status (indexed by plasma levels of vitamin C, E, A and $\beta$-carotene) between smokers(n=56) and non-smokers (n=16). No differences were found in plasma antioxidant status, heme protein damage and TBARS concentration of RBC. In experiment two, 46 fasting male smokers from experiment one were divided into 4 groups. The groups were smoking with placebo group(SP, n=14), smoking cessation with vitamins supplementatin group (SV, n=13), smoking cessation with placebo group (NSP, n=9) and smoking cessation with vitamins supplementation group (NSV, n=10). After supplementing antioxidant vitamins, significant increases were seen in plasma vitamins supplementation group (NSV, n=10). After supplementing antioxidant vitamins, significant increases were seen plasma vitamin C (p<0.05) and vitamin E levels (p<0.05). The plasma vitamin E level was highest in the NSV group. Vitmain E and C supplementation provided some protection against heme proteins and lipid damage by lowering methemoglobin, hemolysis and TBARS concentration of RBC. Smoking cessation significantly decreased TBARS of RBC and plasma total cholesterol concentration. Supplementing vitamin E and C with smoking cessation considerably lowered plasma total cholesterol. These results point to a special association among smoking, oxidative damage and plasma antioxidant vitamin status. They indicate that increases in plasma antioxidant status can be detected after the supplementation of vitamin C and E and that smoking cessation had an additional effect on plasma vitamin E level. The present data suggest that improved antioxidant status induced by antioxidant supplementation or smoking cessation may help prevent oxidative damage in smokers.