• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.156-161
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• 2004

We investigated the effects of oxidizer additive on the performance of Cu-CMP process using commonly used tungsten slurry. In order to compare the removal rate and non-uniformity as a function of oxidizer contents, we used alumina-based tungsten slurry and copper blanket wafers deposited by DC sputtering method. According to the CMP removal rates and particle size distribution, and the microstructures of surface layer by SEM image as a function or oxidizer contents were greatly influenced by the slurry chemical composition of oxidizers. The difference in removal rate and roughness of copper surface are believed to cause by modification in the mechanical behavior of $Al_2$O$_3$abrasive particles in CMP slurry.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.48.1-48.1
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• 2010

Cu has been used for metallic interconnects in ULSI applications because of its lower resistivity according to the scaling down of semiconductor devices. The resistivity of Cu lines will affect the RC delay and will limit signal propagation in integrated circuits. In this study, we investigated the characteristics of electroplated Cu films according to the variation of concentration of organic additives. The plating electrolyte composed of $CuSO_4{\cdot}5H_2O$, $H_2SO_4$ and HCl, was fixed. The sheet resistance was measured with a four-point probe and the material properties were investigated with XRD (X-ray Diffraction), AFM (Atomic Force Microscope), FE-SEM (Field Emission Scanning Electron Microscope) and XPS (X-ray Photoelectron Spectroscopy). From these experimental results, we found that the organic additives play an important role in formation of Cu film with lower resistivity by EPD.

• Journal of the Speleological Society of Korea
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• no.76
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• pp.15-17
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• 2006

[ $YBa_2Cu_3O_{7-{\delta}}$ ] superconductor films have been prepared on silver substrates by electrophoretic deposition. As silver does not react with $YBa_2Cu_3O_{7-{\delta}}$ compound and has little influence on its superconductivity, it is usually doped in $YBa_2Cu_3O_7$ to improve the strength of the material and eliminate micro cracks. It has been proved that Ag additive can lower the melting temperature of $YBa_2Cu_3O_{7-{\delta}}$ and act as linking bridge among $YBa_2Cu_3O_{7-{\delta}}$ particles, thus in this paper Ag doped $YBa_2Cu_3O_{7-{\delta}}$ thick films are prepared by electrophoretic co deposition. As there are only some referenced experience formula and models for co electrophoretic deposition and does not exist unified explanation, the behavior of Ag particles during co electrophoretic deposition is also studied.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.522-531
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• 2003

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+{\delta}}$ high- $T_{c}$ superconductors containing MgO as an additive were fabricated by a solid-state reaction method. Samples with MgO of 5~30 wt% each were sintered at 820~86$0^{\circ}C$ for 24 hours. The structural characteristics, critical temperature, grain size and image of mapping with respect to MgO contents were analyzed by XRD(X-Ray Diffraction), SEM(Scanning Electron Microscope) and EDS(Energy dispersive X-ray spectrometer) respectively. As MgO contents increased, intensity of MgO Peaks and ratio of Bi-2212 phase in superconductors intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.178-178
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• 2015

SAP 씨앗층용 구리필름에 대한 결정구조와 에칭속도의 상관관계를 알아보았다. 그 결과, 저지수 면보다는 고지수면이 우선적으로 성장되어 있는 구리피막이 높은 에칭속도를 나타내었다. 이와 같은 우선결정방위와 에칭속도의 관계를 결정구조적인 관점에서 해석하였다.

• Journal of Powder Materials
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• v.26 no.5
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• pp.405-409
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• 2019

Piezoelectric ceramic specimens with the $Pb(Mg_{1/3}Nb_{2/3})_{0.65}Ti_{0.35}O_3$ (PMN-PT) composition are prepared by the solid state reaction method known as the "columbite precursor" method. Moreover, the effects of the $Li_2O-Bi_2O_3$ additive on the microstructure, crystal structure, and piezoelectric properties of sintered PMN-PT ceramic samples are investigated. The addition of $Li_2O-Bi_2O_3$ lowers the sintering temperature from $1,200^{\circ}C$ to $950^{\circ}C$. Moreover, with the addition of >5 wt.% additive, the crystal structure changes from tetragonal to rhombohedral. Notably, the sample with 3 wt.% additive exhibits excellent piezoelectric properties ($d_{33}=596pC/N$ and Kp = 57%) and a sintered density of $7.92g/cm^3$ after sintering at $950^{\circ}C$. In addition, the sample exhibits a curie temperature of $138.6^{\circ}C$ at 1 kHz. Finally, the compatibility of the sample with a Cu electrode is examined, because the energy-dispersive X-ray spectroscopy data indicate the absence of interdiffusion between Cu and the ceramic material.

• Journal of Powder Materials
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• v.30 no.6
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• pp.463-469
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• 2023

Aluminum alloys, known for their high strength-to-weight ratios and impressive electrical and thermal conductivities, are extensively used in numerous engineering sectors, such as aerospace, automotive, and construction. Recently, significant efforts have been made to develop novel aluminum alloys specifically tailored for additive manufacturing. These new alloys aim to provide an optimal balance between mechanical properties and thermal/electrical conductivities. In this study, nine combinatorial samples with various alloy compositions were fabricated using direct energy deposition (DED) additive manufacturing by adjusting the feeding speeds of Al6061 alloy and Al-12Si alloy powders. The effects of the alloying elements on the microstructure, electrical conductivity, and hardness were investigated. Generally, as the Si and Cu contents decreased, electrical conductivity increased and hardness decreased, exhibiting trade-off characteristics. However, electrical conductivity and hardness showed an optimal combination when the Si content was adjusted to below 4.5 wt%, which can sufficiently suppress the grain boundary segregation of the α-Si precipitates, and the Cu content was controlled to induce the formation of Al₂Cu precipitates.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.3
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• pp.63-71
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• 2022

In this study, the interfacial reaction and drop impact reliability of Sn-Ag-Cu (SAC) solder and electroless nickel autocatalytic gold (ENAG) were studied. In addition, the solder joint properties with the ENAG surface finish was compared with electroless nickel immersion gold (ENIG) and electroless nickel electroless palladium immersion gold (ENEPIG). The IMC thickness of SAC/ENAG and SAC/ENEPIG were 1.15 and 1.12 ㎛, respectively, which were similar each other. The IMC thickness of the SAC/ENIG was 2.99 ㎛, which was about two times higher than that of SAC/ENAG. Moreover, it was found that the IMC thickness of the solder joint was affected by the metal turnover (MTO) condition of the electroless Ni(P) plating solution, and it was found that the IMC thickness increased when the MTO increased from 0 to 3. The shear strength of SAC/ENEPIG was the highest, followed by SAC/ENAG and SAC/ENIG. It was found that when the MTO increased, the shear strength was lowered. In terms of brittle fracture, SAC/ENEPIG was the lowest among the three joints, followed by SAC/ENAG and SAC/ENIG. Likewise, it was found that as MTO increased, brittle fracture increased. In the drop impact test, it was confirmed that the 0 MTO condition had a higher average number of failures than the 3 MTO condition, and the average number of failures was also higher in the order of SAC/ENEIG, SAC/ENAG, and SAC/ENIG. As a result of observing the fracture surface after the drop impact, it was found that the fracture was between the IMC and the Ni(P) layer.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.3
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• pp.55-61
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• 2022

In this study, properties of Pb-free solder joints which were combined using Sn-3.0Ag-0.5Cu (SAC305) Pb-free solder with a mid-temperature type of melting temperature and Sn-57Bi-1Ag Pb-free solder with a low-temperature type of melting temperature were reported. Combined Pb-free solder joints were formed by reflow soldering processes with ball grid array (BGA) packages which have SAC305 solder balls and flame retardant-4 (FR-4) printed circuit boards (PCBs) which printed Sn-57Bi-1Ag solder paste. The reflow soldering processes were performed with two types of temperature profiles and interfacial properties of combined Pb-free solder joints such as interfacial reactions, formations of intermetallic compounds (IMCs), diffusion mechanisms of Bi, and so on were analyzed with the reflow process conditions. In order to compare reliability characteristics of combined Pb-free solder joints, we also conducted thermal shock test and analyzed changes of mechanical properties for joints from a shear test during the thermal shock test.