• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.737-741
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• 2005

In this study, the effect of copper content on the NO removal efficiency by Cu/MCM-41 has been investigated. MCM-41 was prepared by hydrothermal synthesis using a gel mixture of colloidal silica solution and cetyltrimethylammonium. Cu/MCM-41 was manufactured with copper content (5, 10, 20, and 40%) in Cu(II) acetylacetonate. The surface properties of MCM-41 were investigated by using pH, XRD, and FT-IR analyses. $N_2/77K$ adsorption isotherm characteristics, including the specific surface area and micropore volume were studied by BET's equation and Boer's t-plot methods. NO removal efficiency was confirmed by gas chromatography technique. From the experimental results, the MCM-41 was analyzed to have the surface functional groups of Si-OH and Si-O-Si and the characteristic diffraction lines (100), (110), (200), and (210) corresponding to a hexagonal arrangement structure. The copper content supported on MCM-41 appeared to increase the NO removal efficiency in spite of decreasing the specific surface areas or micropore volumes. Consequently, it was found that the copper content in Cu/MCM-41 played an important role in improving the NO removal efficiency, which was mainly attributed to the catalytic reactions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.435-437
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• 2002

Polishing of copper, a process called copper chemical mechanical polishing, is a critical, intermediate step in the planarization of silicon wafers. During polishing, the electrodeposited copper films are removed by slurries: and the differential polishing rates between copper and the surrounding silicon dioxide leads to a greater removal of the copper. The differential polishing develops dimples and furrows; and the process is called dishing and erosion. In this work, we present the results of experiments on dishing and erosion of copper-CMP, using patterned silicon wafers. Results are analyzed for the pattern factors and properties of the copper layers. Three types of pads - plain, perforated, and grooved - were used for polishing. The effect of slurry chemistries and pad soaking is also reported.

• Environmental Engineering Research
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• v.7 no.1
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• pp.49-57
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• 2002

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.24-29
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• 2005

Chemical mechanical polishing (CMP) has been widely accepted for the global planarization of multi-layer structures in semiconductor manufacturing. Copper has been the candidate metallization material for ultra-large scale integrated circuits (ULSIs), owing to its excellent electro-migration resistance and low electrical resistance. However, it still has various problems in copper CMP process. Thus, it is important to understand the effect of the process variables such as turntable speed, head speed, down force and back pressure are very important parameters that must be carefully formulated in order to achieve desired the removal rates and non-uniformity. Using a design of experiment (DOE) approach, this study was performed investigating the main effect of the variables and the interaction between the various parameters during CMP. A better understanding of the interaction behavior between the various parameters and the effect on removal rate, non-uniformity and ETC (edge to center) is achieved by using the statistical analysis techniques. In the experimental tests, the optimum parameters which were derived from the statistical analysis could be found for higher removal rate and lower non-uniformity through the above DOE results.

• Advances in environmental research
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• v.7 no.3
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• pp.225-237
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• 2018

The sorption of metal ions with low-cost adsorbents plays an important role in sustainable development. In the present study, the efficacy of sugarcane bagasse, rain tree fruits (samaneasaman), banana stem and their mixtures, used as bio-sorbents, in the removal of Cu(II) and Pb(II) ions from aqueous solution is evaluated. Batch studies are conducted, and residual ions were measured using Inductively Coupled Plasma (ICP)-atomic spectrometer. Effect of pH, initial metal ion concentration, reaction time and adsorbent dosage are studied. The Pb(II) removal efficiency was observed to be 97.88%, 98.60% and 91.74% for rain tree fruits, banana stem and a mixture of adsorbents respectively. The highest Cu(II) ion removal was observed for sugarcane bagasse sorbent with an efficiency of 82.10% with a pH of 4.5 and a reaction time of 90 min. Finally, desorption studies were carried out to study the leaching potential of adsorbent, and it was found that the adsorbent is stable in water than the other leaching agents such as HCl, ammonium acetate, Sodium EDTA. Hence, these adsorbents can be effectively used for the removal of these heavy metals.

• Current Photovoltaic Research
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• v.7 no.1
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• pp.21-27
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• 2019

Lifetime of Si photovoltaics modules are about 25 years and a large amount of waste modules are expected to be discharged in the near future. Therefore, the extraction and collection of valuable metals out of discharged Si modules will be one of the important technologies. In this study, we demonstrated that supercritical $CO_2$ extraction method can be effectively used to remove Cu, one of the abundant elements in the module, as well as its oxide form, $Cu_2O$. Especially, we proved that the addition of hexane as co-solvent is effective for the removal of both materials. The optimal ratio of $CO_2$ and hexane was 4:1 at a fixed temperature and pressure of $250^{\circ}C$ and 250 bar, respectively. In addition, it was proven that the removal of $Cu_2O$ was preceded via reduction of $Cu_2O$ to Cu.

• Journal of Life Science
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• v.8 no.2
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• pp.208-215
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• 1998

It was investigated the biosorption performances of copper by the immobilized biomass of nonliving marine brown alge h. fusiformis by each of the Ca-alginate method(Ca-ALG), Ba-alginate method(Ba-ALG), polyethylene glycol method(PEG), and carrageenan method (CARR). The copper removal performance increased but the copper uptake decreased as the biomass amount was increased. However, the copper uptake by the immobilized biomass increased with increasing initial copper concentration. The copper uptake by the immobilized biomass of the immobilization method decreased in the following sequence; Ca-ALG>Ba-ALG>PEG>CARR among the immoblization emthods. The copper uptake by the immobilized biomass followed the Langmuir isotherm better than the Freundlich isotherm.

• Resources Recycling
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• v.28 no.5
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• pp.74-79
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• 2019

The effects of equivalent of iron powder, particle size, agitation speed on the removal efficiency of copper ion were investigated by adding iron powder as cementation agents to simulated mine drainage solution with 117.15 mg/L Cu ion. The 50 % of Cu was removed at 90 min with 2 equivalent of iron powder while more than 99 % of Cu was removed at 60 min with 16 equivalent at 200 rpm and $20^{\circ}C$. The removal efficiencies of Cu ion were not different using 2 equivalent of $48{\mu}m$ and $150{\mu}m$ iron powder, and the removal efficiency increased rapidly with increasing the agitation speed to more than 400 rpm. This lower removal efficiency resulted from agglomeration of iron powder observed by SEM, which could reduce the effective specific surface area. More than 99 % of copper ion was removed using 2 equivalent of $48{\mu}m$ iron powder at 60 min, 600 rpm and $20^{\circ}C$.

• Carbon letters
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• v.8 no.4
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• pp.321-325
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• 2007

The oxygen and nitrogen enriched activated carbons were obtained from modification of commercial activated carbon by using nitric acid, sodium hydroxide and urea. Zeta-potentials of modified activated carbons were investigated in relation to copper ion adsorption. The structural properties of modified activated carbons were not so much changed, but the zeta-potentials and isoelectric points were considerably changed. The zeta-potential of nitric acid modified activated carbon was the most negative than other activated carbons in the entire pH region, and the $pH_{IEP}$ was shifted from pH 4.8 to 2.6, resulted in the largest copper ion adsorption capacities compare with other activated carbons in the range of pH 3~6.5. In case of urea modified activated carbon, copper ion adsorption was larger than that of the as-received activated carbon from pH 2 to pH 6.5 even though the $pH_{IEP}$ was shifted to pH 6.0, it was due to the coordination process operated between nitrogen functional groups and copper ion. The adsorption capacity of copper ion was much influenced by zeta-potential and $pH_{IEP}$ of carbon adsorbent.

• Tribology and Lubricants
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• v.34 no.6
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• pp.226-234
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• 2018

Copper chemical mechanical planarization (CMP) has become a key process in integrated circuit (IC) technology. The results of copper CMP depend not only on the mechanical abrasion, but also on the slurry chemistry. The slurry used for Cu CMP is known to have greater chemical reactivity than mechanical material removal. The Cu CMP slurry is composed of abrasive particles, an oxidizing agent, a complexing agent, and a corrosion inhibitor. Citric acid can be used as the complexing agent in Cu CMP slurries, and is widely used for post-CMP cleaning. Although many studies have investigated the effect of citric acid on Cu CMP, no studies have yet been conducted on the interfacial friction characteristics and step height reduction in CMP patterns. In this study, the effect of citric acid on the friction characteristics and step height reduction in a copper wafer with varying pattern densities during CMP are investigated. The prepared slurry consists of citric acid ($C_6H_8O_7$), hydrogen peroxide ($H_2O_2$), and colloidal silica. The friction force is found to depend on the concentration of citric acid in the copper CMP slurry. The step heights of the patterns decrease rapidly with decreasing citric acid concentration in the copper CMP slurry. The step height of the copper pattern decreases more slowly in high-density regions than in low-density regions.