• Korean Journal of Materials Research
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• v.9 no.3
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• pp.288-294
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• 1999

In the flip chip interconnection using solder bump, the Under Bump Metallurgy (UBM) is required to perform multiple functions in its conversion of an aluminum bond pad to a solderable surface. In this study, various UBM systems such as $Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 5\mu\textrm{m}, Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}, al 1\mu\textrm{m}/Ni 0.2\mu\textrm{m} / Cu 1\mu\textrm{m} and Al 1\mu\textrm{m}/Pd 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}$ for flip chip interconnection using the low melting point eutectic 63Sn-37Pb solder were investigated and compared to their metallurgical properties. $100\mu\textrm{m}$ size bumps were prepared for using an electroplating process. The effects of the number of reflows and aging time on the growth of intermetallic compounds(IMC) were investigated. $Cu_6Sn_5$ and $Cu_3Sn$ IMC were abserved after aging treatment in the UBM system with thick coper $(Al 1\mu\textrm{m}/Ti 0.2\mu\textrm{m}/Cu 5\mu\textrm{m})$. However only the $Cu_6Sn_5$ was detected in the UBM system with $1\mu\textrm{m}$ thick copper even after 2 reflow and 7 day aging at $150^{\circ}C$. Complete Cu consumption by Cu-Sn IMC growth gives rise to a direct contact between solder inner layer such as Ti, Ni and Pd, and hence to possibly cause reactions between two of them. In this study, however, only for the Pd case, IMC of PdSn. was observed by Cu consumption. UBM interfacial reactions with s이der affected the adhesion strength ot s이der balls after s이der reflow and annealing treatment.

• Current Photovoltaic Research
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• v.11 no.2
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• pp.39-43
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• 2023

Carrier-selective contacts (CSCs) solar cells are considerably attractive on highly efficient crystalline silicon heterojunction (SHJ) solar cells due to their advantages of high thermal tolerance and the simple fabrication process. CSCs solar cells require a hole selective contact (HSC) layer that selectively collects only holes. In order to selectively collect holes, it must have a work function characteristic of 5.0 eV or more when contacted with n-type Si. The VO_x, NiO_x, and CuI_x thin films were fabricated and analyzed respectively to confirm their potential usage as a hole-selective contact (HSC) layer. All thin films showed characteristics of band-gap engergy > 3.0 eV, work function > 5.0 eV and minority carrier lifetime > 1.5 ms.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.394-398
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• 1998

An optimum synthetic condition was studied for the MCS used as a silicone monomer. The contact mixture was made from the four component catalyst system($CuCl/ZnCl_2/Sn/Cd$) and silicon particles. The contact mass was used for a series of experiments with methyl chloride, which were designed and done to explore the optimum condition for MCS synthesis by an experimental design method. The optimum temperature and MeCl flow rate, which were obtained using 50g contact mass at 60rpm and 1 atm, were in the range of $300-305^{\circ}C$ and of 70-80ccm. Also a continuous run was performed to confirm the conditions. The results showed that the average reaction rate and selectivity were 170(g-MCS/hr.kg-Si) and 0.05 respectively at 67% conversion of MeCl and 92% silicon utilization rate. Also the parameters of overall reaction rate equation and a total pressure were estimated on the basis of the results of the continuous run.

• Journal of the Korean institute of surface engineering
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• v.39 no.2
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• pp.57-63
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• 2006

In this study, In-base solder was applied to the interface between $Bi_2Sr_2Ca_1Cu_2O_x(Bi_{2212})$ superconductor and Cu-Ni shunt metal at the temperature lower than $150^{\circ}C$. Most of the cases, $Bi_{2212}$ superconductor was precoated with Ag by electroplating in order to improve the contact properties of the solder layer. When the superconductor was directly soldered on to the superconductor, the solder was easily separated without external force. The shear strength of the contact between superconductor and shunt metal increased from 69.2 kgf to 74.4 kgf and 80.1 kgf, as the current density of the Ag electroplating was changed from 63 mA to 96 mA and 126 mA, respectively. The contact strength also increased to 49.9 kgf and 69.2 kgf when thickness of the electroplated Ag layer increased to $5{\mu}m$ and $10{\mu}m$, reapectively.

• Tribology and Lubricants
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• v.28 no.4
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• pp.173-177
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• 2012

We used contact resonance force microscopy (CRFM) technique to determine the quantitative elastic properties of multiple materials integrated on the sub micrometer scale. The CRFM approach measures the frequencies of an AFM cantilever's first two flexural resonances while in contact with a material. The plain strain modulus of an unknown or test material can be obtained by comparing the resonant spectrum of the test material to that of a reference material. In this study we examined the following bumping materials for flip chip by using copper electrode as a reference material: NiP, Solder (Sn-Au-Cu alloy) and under filled epoxy. Data were analyzed by conventional beam dynamics and contact dynamics. The results showed a good agreement (~15% difference) with corresponding values determined by nanoindentaion. These results provide insight into the use of CRFM methods to attain reliable and accurate measurements of elastic properties of materials on the nanoscale.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.25-28
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• 2002

Contact type Ic measurement system is needed to measure Ic continuously for long Bi-2223 tapes. Voltage and current terminals were designed several shapes for 4-probe method Ic measurement. Voltage terminals were made with brass and current terminals were made with Cu. We used 2 kinds of Bi-2223 tapes with different strength. When we measured Ic of Bi-2223 tape with Ag-Mg sheath, The proper weight was 0.3 kg and sharp pin type was better. according to voltage terminal shape and load. In case of Bi-2223 tape with Ag-Mn sheath, the proper terminal weight was 4 kg and sharp pin type was bad. It was possible to make continuous contact type Ic measurement system because We could get proper data - terminal shapes and loads - through these experiments.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.2
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• pp.203-214
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• 2014

We measured the contact dermatitis-causing substances concentrations in 28 commercial oxidative hair-coloring products. This study was aimed to provide the fundamental data about oxidative hair-coloring products. We selected 10 oxidation dyes (p-phenylenediamine, toluene-2,5-diamine, m-phenylenediamine, nitro-p-phenylenediamine, p-aminophenol, m-aminophenol, o-aminophenol, p-methylaminophenol, N,N'-bis(2-hydroxyethyl)-p-phenylenediamine sulfate, 2-methyl-5-hydroxyethylaminophenol) and 4 heavy metal (nikel; Ni, chromium; Cr, cobalt; Co, copper; Cu) as contact dermatitis-causing substances. To identify 10 oxidation dyes, hexane-2% sodium sulfite was used for the rapid and simple extraction and ultra performance liquid chromatography (UPLC) analysis was used for simultaneous analysis in 12 minutes. 10 oxidative dyes were detected as indicated on the product packaging and each concentration was lower than prescribed upper concentration limit by pharmaceutical manufacturing standards. And we analysed inductively coupled plasma-optical emission spectrophotometer (ICP-OES) for content search of heavy metal after microwave digestion. The heavy metal average concentration in oxidative hair-coloring products was 0.572 ${\mu}g/g$ for Ni, 3.161 ${\mu}g/g$ for Cr, 2.029 ${\mu}g/g$ for Co, 0.420 ${\mu}g/g$ for Cu, respectively. The average of concentration in powder type (henna) was higher than those of other foam and cream type oxidative hair-coloring products as follows; 1.800 ${\mu}g/g$ for Ni, 10.127 ${\mu}g/g$ for Cr, 7.082 ${\mu}g/g$ for Co, 1.451 ${\mu}g/g$ for Cu. Hair coloring products were classified into the six colors - black, dark brown, brown, dark brown, light brown, red brown and analyzed. Brown color had the highest average concentration of Co and the others had the highest average concentration of Cr.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.86.2-86.2
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• 2015

Cu2ZnSn(S,Se)4 thin film solar cells have been fabricated using sputtered Cu/Sn/Zn metallic precursors on Mo coated sodalime glass substrate without using a toxic H2Se and H2S atmosphere. Cu/Sn/Zn metallic precursors with various thicknesses were prepared using DC magnetron sputtering process at room temperature. As-deposited metallic precursors were sulfo-selenized inside a graphite box containing S and Se pellets using rapid thermal processing furnace at various sulfur to selenium (S/Se) compositional ratio. Thin film solar cells were fabricated after sulfo-selenization process using a 65 nm CdS buffer, a 40 nm intrinsic ZnO, a 400 nm Al doped ZnO, and Al/Ni top metal contact. Effects of sulfur to selenium (S/Se) compositional ratio on the microstructure, crystallinity, electrical properties, and cell efficiencies have been studied using X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope, I-V measurement system, solar simulator, quantum efficiency measurement system, and time resolved photoluminescence spectrometer. Our fabricated Cu2ZnSn(S,Se)4 thin film solar cell shows the best conversion efficiency of 9.24 % (Voc : 454.6 mV, Jsc : 32.14 mA/cm2, FF : 63.29 %, and active area : 0.433 cm2), which is the highest efficiency among Cu2ZnSn(S,Se)4 thin film solar cells prepared using sputter deposited metallic precursors and without using a toxic H2Se gas. Details about other experimental results will be discussed during the presentation.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.398-404
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• 2001

Effects of coating treatment of metallic Cu film on SiC for Al/SiC composite were studied. The Copper was deposited on SiC by electroless plating method. Al/sic composite was fabricated at temperature range of $670^{\circ}C$ to 90$0^{\circ}C$ under vacuum atmosphere. The wetting behavior of Al/SiC composite were analysed by SEM and XRD. The coating treatment on SiC improved wettability of Al melt on SiC considerably comparing to the non coated SiC. This improved wettability seems strongly concerned to the increase of chemical reactivity between coated layer and Al matrix. The improvement of wettability of Al melt on the Cu coated SiC was closely related to in the initial stage of reaction. The metallic film played an important role in reducing the interfacial free energy and breaking down the aluminum oxide film through the reaction with Al melt. The wetting behavior of the as-received SiC with Al melt was not uniform, indicated by the contact angles from less than $97^{\circ}$to more than $97^{\circ}$.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.75-78
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• 2006

In case of contacts between semiconductor and metal in semiconductor circuits, they become unstable because of thermal budget. To prevent these problems, we use diffusion barrier that has a good thermal stability between metal and semiconductor. So we consider the diffusion barrier to prevent the increase of contact resistance between the interfaces of metals and semiconductors, and the increase of resistance and the reaction between the interfaces. In this paper we deposited tungsten boron carbon nitride (W-B-C-N) thin film on silicon substrate. The impurities of the $1000\;{\AA}-thick$ W-B-C-N thin films provide stuffing effect for preventing the inter-diffusion between metal thin films $(Cu-2000\;{\AA})$ and silicon during the high temperature $(700\~1000^{\circ}C)$ annealing process.