• Korean Chemical Engineering Research
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• v.43 no.1
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• pp.98-102
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• 2005

This article describes a study of chemical vapor deposition (CVD) of copper thin films on TiN substrates using (HFAC)Cu(DMB) as a precursor. The surface morphology and conformality of the Cu films as functions of substrate temperature and the presence or absence of iodine have been investigated. The surface roughness was increased significantly along with decrement of the step coverage by increasing the deposition temperature. The highest conformal films with the lowest surface roughness were obtained using the process of copper CVD, where iodine vapor were discretely introduced into the reactor during the growth of copper.

• Resources Recycling
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• v.20 no.6
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• pp.63-70
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• 2011

Enviromental friendly leaching process for the recovery of cobalt and copper from the cobalt concentrate was investigated by organic acids as a leaching reagent. The experimental parameters, such as organic acid type, concentrations of leachant, time and temperature of the reaction as well as the solid to liquid ratio were tested to obtain the optinum conditions for the leaching of cobalt and copper. The results showed that citric acid was the most effective leaching reagent among the organic acids used in this experiment. About 99% of cobalt, 95% of copper and 70% of nickel was dissolved by 2.0 M of citric acid. Addition of 3.0 vol.% of hydrogen perioxide was effective to enhance the leaching efficiency and the optinum temperature was found to be about $70^{\circ}C$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.726-729
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• 2010

Copper Pillar Tin Bump (CPTB) was investigated for high density chip interconnect technology development, which was prepared by electroplating and electro-less plating methods. Copper pillar tin bumps that have $100{\mu}m$ pitch were introduced with fabrication process using a KM-1250 dry film photoresist (DFR), with copper electroplating for Copper Pillar Bump (CPB) formation firstly, and then tin electro-less plating on it for control oxidation. Electric resistivity and mechanical shear strength measurements were introduced to characterize the oxidation effects and bonding process as a function of thermo-compression. Electrical resistivity increased with increasing oxidation thickness, and shear strength had maximum value with $330^{\circ}C$ and 500 N thermo-compression process. Through the simulation work, it was proved that when the CPTB decreased in its size, it was largely affected by the copper oxidation.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.29-36
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• 2008

In this paper, mechanical reliability issues of copper through-wafer interconnections are investigated numerically and experimentally. A hermetic wafer level packaging for MEMS devices is developed. Au-Sn eutectic bonding technology is used to achieve hermetic sealing, and the vertical through-hole via filled with electroplated copper for the electrical connection is also used. The MEMS package has the size of $1mm{\times}1mm{\times}700{\mu}m$. The robustness of the package is confirmed by several reliability tests. Several factors which could induce via hole cracking failure are investigated such as thermal expansion mismatch, via etch profile, and copper diffusion phenomenon. Alternative electroplating process is suggested for preventing Cu diffusion and increasing the adhesion performance of the electroplating process. After implementing several improvements, reliability tests were performed, and via hole cracking as well as significant changes in the shear strength were not observed. Helium leak testing indicated that the leak rate of the package meets the requirements of MIL-STD-883F specification.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.203-207
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• 2003

Amphibian biodiversity, community structure and habitats were surveyed in the Mt. Myungji area from April 2002 to March 2003. During the survey period 2orders, 4 families, 7 species of amphibians were observed. Bombina orientalis (DI =45.1%) was dominant and Bufo stejnegeri (DI = 12.8%), Rana rugosa and Rana dybowskii (DI = 9.9% each) Rana nigromaculata and Rana huanrenensis (DI 1.4% each), and Onycodactylus fisheri (DI = 7.0%) followed. Frequency of occurrence of O. fisheri and B. stejnegeri was largely different according to the altitude and human residence in their habitats.R. nigromaculata and R. huanrenensis showed low frequency of occurrence (<10%) suggesting the decrease in habitation density in this area. The species richness (R'), general diversity (H'), and evenness (E') of amphibians in this area were 0.98, 2.12, and 0.76, respectively, suggesting relatively healthy condition of amphibian community in this area.

• Resources Recycling
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• v.17 no.3
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• pp.48-55
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• 2008

Leaching of copper and silver from mobile phone PCBs(printed circuit boards) with nitric acid was performed to investigate the effects of nitric acid concentrations, leaching temperatures, agitation speeds, and pulp densities on the leaching behaviors of Cu and Ag. The leaching rate considerably increased with increasing acid concentration and temperature. The leaching ratios of Cu and Ag were found to be 96.4% and 96.5%, respectively, under the optimum condition; at $80^{\circ}C$ with 2mol/L $HNO_3$ and 120g/L in pulp density within 39minutes. The kinetic parameters were determined based on the shrinking core model with reaction control corresponding to small particles. The activation energies for the leaching of copper and silver were found to be 45.5kJ/mol and 60.5kJ/mol at $35{\sim}80^{\circ}C$ with 2mol/L $HNO_3$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.1
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• pp.37-42
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• 2000

Copper thin films have been prepared by a metal organic chemical vapor deposition (MOCVD) technology on polyimide and TiN substrates. The Cu-MOCVD technology has advantages of the high deposition rate and the good step coverage compared with the conventional physical vapor deposition (PVD) technology in several industrial applications. The Cu films have been deposited with varying the experimental conditions of substrate temperatures and copper source vapor pressures. The films were annealed in a vacuum condition after the deposition, and the annealing effect on the electrical properties of the films was measured. The crystallinity and the microstructures of the films were observed by scanning electron microscopy (SEM), and the electrical resistivity was measured by 4-point probe. In the case of the Cu deposition on TiN substrate, the best electrical property of the films was measured for the samples prepared at 18$0^{\circ}C$. Very high deposition rate of the Cu film up to 250 nm/min was obtained on the polyimide substrate when the mixture of liquid and vapour precursor was used.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.109-114
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• 2021

We investigated the effects of atmospheric hydrogen plasma treatment on Cu-Cu direct bonding. Hydrogen plasma was effective in reducing the surface oxide layer of Cu thin film, which was confirmed by GIXRD analysis. It was observed that larger plasma input power and longer treatment time were effective in terms of reduction and surface roughness. The interfacial adhesion energy was measured by DCB test and it was observed to decrease as the bonding temperature decreased, resulting in bonding failure at bonding temperature of 200℃. In case of wet treatment, strong Cu-Cu bonding was observed above bonding temperature of 250℃.

• Journal of the Korean Wood Science and Technology
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• v.32 no.2
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• pp.1-8
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• 2004

Heavy metals were removed from CCA- and CCFZ- treated wood using a brown-rot fungi Tyromyces palustris. The amount of effective elements extracted from treated woods was compared for different treatment methods. The relationship between the amount of heavy metals removed and concentrations of oxalic acid for treated wood was examined. Also, the relationship between mycelia weight and removal rate was examined. The removed quantity of heavy metal from treated wood according to fermentation methods was examined. The extraction amount of chromium and arsenic components increased with increasing oxalic acid concentration, but the extraction amount of copper did not improved much. A 287 mg of mycelia weight can remove chromium and arsenic over 60% in 3 g CCA chips and copper was also removed over 50%. The chromium, copper and arsenic were removed over 60% by shaking fermentation, the removal rate of copper by static cultivation was higher than that of shaking fermentation. The removal rate of chromium, copper and arsenic were 72%, 61% and 59% with air-lift bioreactor, respectively.

• Korean Journal of Poultry Science
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• v.38 no.2
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• pp.121-128
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• 2011

This study was conducted to investigate the effects of dietary supplementation of Cu-sulfate, Cu-methionine chelate (Cu-Met) and Cu-soy proteinate (Cu-SP) on the performance, blood parameters and mineral contents of muscle. It was conducted with a total of 1,000 one d old broilers chickens (Ross$^{(R)}$) which were assigned to four dietary treatments; Control, Cu sulfate (200 ppm Cu as $CuSO_4{\cdot}5H_2O$), Cu-Met (200 ppm Cu as Cu-methionine chelate), Cu-SP (200 ppm Cu as Cu-soy proteinate). There were significant differences (p<0.05) among treatments in weight gain. Weight gain of Cu treated groups were higher than the control during 3~5 wk. There were significant differences (p<0.05) among treatments in feed intake during 0~3 wk. Cu-Met was significantly (p<0.05) lower than the control but the differences among Cu treatments were not significant. There were significant differences (p<0.05) among treatments in feed conversion rate (FCR). Cu treated groups were lower than the control during the whole period. Production efficiency factor (PEF) was significantly higher (p<0.01) in Cu treated groups than the control. Nutrient availabilities of diets were not significantly different among the treatments. The count of white blood cell (WBC) and eosinophil (EO) were lower in Cu-SP treatment than in the control. Copper concentration in the liver was significantly (p<0.01) higher in Cu treated groups than the control. Zinc concentration in the breast and wing muscle was lower in Cu treated and that of leg muscle was higher in Cu-Met than the control. The result of this experiment showed that Cu supplementation at the level of 200 ppm as Cu sulfate, Cu-Met and Cu-SP improves weight gain (4~5 wk), FCR and PEF. Differences among Cu sources were not significant.