• Korean Chemical Engineering Research
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• v.54 no.6
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• pp.723-733
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• 2016

Intensive researches have been focused on the 3-dimensional packaging technology using through silicon via (TSV) to overcome the limitation in Cu interconnection scaling. Void-free filling of TSV by the Cu electrodeposition is required for the fabrication of reliable electronic devices. It is generally known that sufficient inhibition on the top and the sidewall of TSV, accompanying the selective Cu deposition on the bottom, enables the void-free bottom-up filling. Organic additives contained in the electrolyte locally determine the deposition rate of Cu inside the TSV. Investigation on the additive chemistry is essential for understanding the filling mechanisms of TSV based on the effects of additives in the Cu electrodeposition process. In this review, we introduce various filling mechanisms suggested by analyzing the additives effect, research on the three-additive system containing new levelers synthesized to increase efficiency of the filling process, and methods to improve the filling performance by modifying the functional groups of the additives or deposition mode.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.374-378
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• 2012

In an effort to overcome the problems which arise when fabricating high-aspect-ratio TSV(through silicon via), we performed experiments involving the void-free Cu filling of a TSV(10~20 ${\mu}m$ in diameter with an aspect ratio of 5~7) by controlling the plating DC current density and the additive SPS concentration. Initially, the copper deposit growth mode in and around the trench and the TSV was estimated by the change in the plating DC current density. According to the variation of the plating current density, the deposition rate during Cu electroplating differed at the top and the bottom of the trench. Specifically, at a current density 2.5 mA/$cm^2$, the deposition rate in the corner of the trench was lower than that at the top and on the bottom sides. From this result, we confirmed that a plating current density 2.5 mA/$cm^2$ is very useful for void-free Cu filling of a TSV. In order to reduce the plating time, we attempted TSV Cu filling by controlling the accelerator SPS concentration at a plating current density of 2.5 mA/$cm^2$. A TSV with a diameter 10 ${\mu}m$ and an aspect ratio of 7 was filled completely with Cu plating material in 90 min at a current density 2.5 mA/$cm^2$ with an addition of SPS at 50 mg/L. Finally, we found that TSV can be filled rapidly with plated Cu without voids by controlling the SPS concentration at the optimized plating current density.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.3
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• pp.114-121
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• 2003

Through comparing stress state of TEOS and SiLK-embedded structures, the effect of low-k materials on stress and stress distribution in via-line structures were investigated using three-dimensional finite element analyses. In the case of TEOS-embedded via-line structures, hydrostatic stress was concentrated at the via and the top of the lines, where the void was suspected to nucleate. On the other hand, in the via-line structures integrated with SiLK, large von-Mises stress is maintained at the via, thus deformation of via is expected as the main failure mode. A good correlation between the calculated results and experimentally observed failure modes according to dielectric materials was obtained.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.63-66
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• 2014

In this study, we investigated the effects of Cu TSV on the thermal management of 3D stacked IC. Combination of backside point-heating and IR microscopic measurement of the front-side temperature showed evolution of hot spots in thin Si wafers, implying 3D stacked IC is vulnerable to thermal interference between stacked layers. Cu TSV was found to be an effective heat path, resulting in larger high temperature area in TSV wafer than bare Si wafer, and could be used as an efficient thermal via in the thermal management of 3D stacked IC.

• Journal of the Korean institute of surface engineering
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• v.55 no.2
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• pp.63-69
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• 2022

Preparing various types of thin films of oxide semiconductors is a promising approach to fabricate efficient photoanodes and photocathodes for hydrogen production via photoelectrochemical (PEC) water splitting. In this work, we investigate the feasibility of an efficient photocathode for PEC water reduction of a p-type oxide semiconductor cupric oxide (CuO) thin film prepared via a facile method combined with sputtering Cu metallic film on fluorine-doped thin oxide (FTO) coated glass substrate and subsequent thermal oxidation of the sputtered Cu metallic film in dry air. Characterization of the structural, optical, and PEC properties of the CuO thin film prepared at various Cu sputtering powers reveals that we can obtain an optimum CuO thin film as an efficient PEC photocathode at a Cu sputtering power of 60 W. The photocurrent density and the optimal photocurrent conversion efficiency for the optimum CuO thin film photocathode are found to be -0.3 mA/cm² and 0.09% at 0.35 V vs. RHE, respectively. These results provide a promising route to fabricating earth-abundant copper-oxide-based photoelectrode for sunlight-driven hydrogen generation using a facile method.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.141-141
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• 2018

Copper is one of the most abundant metals on earth. Its oxide (CuO) is an intrinsically p-type metal-oxide semiconductor with a bandgap ($E_g$) of 1.2-2.0 eV 1. Copper oxide nanomaterials are considered as promising materials for a wide range of applications e.g., lithium ion batteries, dye-sensitized solar cells, photocatalytic hydrogen production, photodetectors, and biogas sensors 2-7. Recently, high-density and uniform CuO nanostructures have been grown on Cu foils in alkaline solutions 3. In 2011, T. Soejima et al. proposed a facile process for the oxidation synthesis of CuO nanobelt arrays using $NH_3-H_2O_2$ aqueous solution 8. In 2017, G. Kaur et al. synthesized CuO nanostructures by treating Cu foils in $NH_4OH$ at room temperature for different treatment times 9. The surface treatment of Cu in alkaline aqueous solutions is a potential method for the mass fabrication of CuO nanostructures with high uniformity and density. It is interesting to compare the gas sensing properties among CuO nanomaterials synthesized by this approach and by others. Nevertheless, none of above studies investigated the gas sensing properties of as-synthesized CuO nanomaterials. In this study, CuO nanowalls versus nanoparticles were synthesized via the oxidation process of Cu foil in NH4OH solution at $50-70^{\circ}C$. The gas sensing properties of the as-prepared CuO nanoplates were examined with $C_2H_5OH$, $CH_3COCH_3$, and $NH_3$ at $200-360^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.5
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• pp.563-571
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• 2012

In 3D integration package using TSV technology, bonding is the core technology for stacking and interconnecting the chips or wafers. During bonding process, however, warpage and high stress are introduced, and will lead to the misalignment problem between two chips being bonded and failure of the chips. In this paper, a finite element approach is used to predict the warpages and stresses during the bonding process. In particular, in-plane deformation which directly affects the bonding misalignment is closely analyzed. Three types of bonding technology, which are Sn-Ag solder bonding, Cu-Cu direct bonding and SiO2 direct bonding, are compared. Numerical analysis indicates that warpage and stress are accumulated and become larger for each bonding step. In-plane deformation is much larger than out-of-plane deformation during bonding process. Cu-Cu bonding shows the largest warpage, while SiO2 direct bonding shows the smallest warpage. For stress, Sn-Ag solder bonding shows the largest stress, while Cu-Cu bonding shows the smallest. The stress is mainly concentrated at the interface between the via hole and silicon chip or via hole and bonding area. Misalignment induced during Cu-Cu and Sn-Ag solder bonding is equal to or larger than the size of via diameter, therefore should be reduced by lowering bonding temperature and proper selection of package materials.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.19-24
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• 2009

Formation of an adhesion/barrier layer and a seed layer by sputtering techniques followed by electroplating has been one of the most widely used methods for the filling of through-Si via (TSV) with high aspect ratio for 3-D packaging. In this research, the adhesion and diffusion-barrier properties of the $TaN_x$ film deposited by reactive sputtering were investigated. The adhesion strength between Cu film and $SiO_2$/Si substrate was quantitatively measured by $180^{\circ}$ peel test and topple test as a function of the composition of the adhesive $TaN_x$ film. As the nitrogen content increased in the adhesive $TaN_x$ film, the adhesion strength between Cu and $SiO_2$/Si substrate increased, which was attributed to the increased formation of interfacial compound layer with the nitrogen flow rate. We also examined the diffusion-barrier properties of the $TaN_x$ films against Cu diffusion and found that it was improved with increasing nitrogen content in the $TaN_x$ film up to N/Ta ratio of 1.4.

• Molecules and Cells
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• v.39 no.3
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• pp.195-203
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• 2016

Copper is an essential element required for a variety of functions exerted by cuproproteins. An alteration of the copper level is associated with multiple pathological conditions including chronic ischemia, atherosclerosis and cancers. Therefore, copper homeostasis, maintained by a combination of two copper ions ($Cu^+$ and $Cu^{2+}$), is critical for health. However, less is known about which of the two copper ions is more toxic or functional in endothelial cells. Cubic-shaped $Cu_2O$ and CuO crystals were prepared to test the role of the two different ions, $Cu^+$ and $Cu^{2+}$, respectively. The $Cu_2O$ crystal was found to have an effect on cell death in endothelial cells whereas CuO had no effect. The $Cu_2O$ crystals appeared to induce p62 degradation, LC3 processing and an elevation of LC3 puncta, important processes for autophagy, but had no effect on apoptosis and necrosis. $Cu_2O$ crystals promote endothelial cell death via autophagy, elevate the level of reactive oxygen species such as superoxide and nitric oxide, and subsequently activate AMP-activated protein kinase (AMPK) through superoxide rather than nitric oxide. Consistently, the AMPK inhibitor Compound C was found to inhibit $Cu_2O$-induced AMPK activation, p62 degradation, and LC3 processing. This study provides insight on the pathophysiologic function of $Cu^+$ ions in the vascular system, where $Cu^+$ induces autophagy while $Cu^{2+}$ has no detected effect.

• Journal of the Korean institute of surface engineering
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• v.46 no.4
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• pp.158-161
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• 2013

Recently, the weight reduction and miniaturization of the electronics have placed great emphasis. The miniaturization of PCB (Printed Circuit Board) as main component among the electronic components has also become progressed. The use of acid copper plating process for Via-Filling effectively forms interlayer connection in build-up PCBs with high-density interconnections. However, in the case of copper-via filled in a bath, which is greatly dependent on the effects of additives. This paper discusses effects of Cl ion on the filling of PCB vias with electrodeposited copper based on both electrochemical experiment and practical observation of cross sections of vias.