• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.555-560
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• 2002

Brazing of Al to Cu using AI-Si-Mg-Bi brazing alloy has been carried out in the vacuum furnace. In the bonded interlayer, there were two kinds of intermetallic compounds. One of these intermetallic compounds was e phase and the other was b phase. The growth of b phase was controlled by diffusion Al into Cu. Deformation behavior of Al-Cu brazing joint was brittle without deformation of the base metal. Shear strength of the joint was only about 20MPa. The shear specimen broken in the intermetallic compound, which was mainly e phase. Shear strength did not depend on the bonding temperature.

• Applied Microscopy
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• 제44권3호
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• pp.105-109
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• 2014

The microstructure of as-quenched $Al_{70}Cu_{18}Mg_{12}$ alloy has been investigated in detail using transmission electron microscopy. Al nano-crystals about 5 nm with a high density are distributed in the amorphous matrix, indicating amorphous matrix nano-composite can be synthesized in Al-Cu-Mg alloy. The high density of Al nano-crystals indicates very high nucleation rate and sluggish growth rate during crystallization possibly due to limited diffusion rate of solute atoms of Cu and Mg during solute partitioning. The result of hardness measurement shows that the mechanical properties can be improved by designing a nano-composite structure where nanometer scale crystals are embedded in the amorphous matrix.

• 한국세라믹학회지
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• 제31권4호
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• pp.381-388
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• 1994

A new process which co-fires the low-firing-substrate and copper conductor was studied to achieve good bond strength and low sheet resistance of conductor. Cupric oxide is used as the precursor of conductive material in the new method and the firing atmosphere of the new process is changed sequently in air H2N2. The addition of cupric oxide and variations of firing atmosphere permited complete binder-burnout in comparison with the conventional method and contributed to the improvement of resistance and bonding behaviors. The potimum conditions of this experiment to obtain the satisfactory resistance and bond strength are as follows (binder-burnout temperature in air; 55$0^{\circ}C$, reducing temperature in H2; 40$0^{\circ}C$ for 30 min, ratio of copper and cupric oxide; 60:40~30:70 wt%). The bonding mechanism between the substrate and metal was explained by metal diffusion layer in the interface and the bond strength mainly depended on the stress caused by the difference of shrinkage and thermal expansion coefficient between the substrate and metal.

• 한국재료학회지
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• 제17권9호
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• pp.484-488
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• 2007

Mo(Ti) alloy and pure Cu thin films were subsequently deposited on $SiO_2-coated$ Si wafers, resulting in $Cu/Mo(Ti)/SiO_2$ structures. The multi-structures have been annealed in vacuum at $100-600^{\circ}C$ for 30 min to investigate the outdiffusion of Ti to Cu surface. Annealing at high temperature allowed the outdiffusion of Ti from the Mo(Ti) alloy underlayer to the Cu surface and then forming $TiO_2$ on the surface, which protected the Cu surface against $SiH_4＋NH_3$ plasma during the deposition of $Si_3N_4$ on Cu. The formation of $TiO_2$ layer on the Cu surface was a strong function of annealing temperature and Ti concentration in Mo(Ti) underlayer. Significant outdiffusion of Ti started to occur at $400^{\circ}C$ when the Ti concentration in Mo(Ti) alloy was higher than 60 at.%. This resulted in the formation of $TiO_2/Cu/Mo(Ti)\;alloy/SiO_2$ structures. We have employed the as-deposited Cu/Mo(Ti) alloy and the $500^{\circ}C-annealed$ Cu/Mo(Ti) alloy as gate electrodes to fabricate TFT devices, and then measured the electrical characteristics. The $500^{\circ}C$ annealed Cu/Mo($Ti{\geq}60at.%$) gate electrode TFT showed the excellent electrical characteristics ($mobility\;=\;0.488\;-\;0.505\;cm^2/Vs$, on/off $ratio\;=\;2{\times}10^5-1.85{\times}10^6$, subthreshold = 0.733.1.13 V/decade), indicating that the use of Ti-rich($Ti{\geq}60at.%$) alloy underlayer effectively passivated the Cu surface as a result of the formation of $TiO_2$ on the Cu grain boundaries.

• 마이크로전자및패키징학회지
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• 제28권3호
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• pp.9-15
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• 2021

최근 반도체 소자의 소형화는 물리적 한계에 봉착했으며, 이를 극복하기 위한 방법 중 하나로 반도체 소자를 수직으로 쌓는 3D 패키징이 활발하게 개발되었다. 3D 패키징은 TSV, 웨이퍼 연삭, 본딩의 단위공정이 필요하며, 성능향상과 미세피치를 위해서 구리 본딩이 매우 중요하게 대두되고 있다. 본 연구에서는 대기중에서의 구리 표면의 산화방지와 저온 구리 본딩에 티타늄 나노 박막이 미치는 영향을 조사하였다. 상온과 200℃ 사이의 낮은 온도 범위에서 티타늄이 구리로 확산되는 속도가 구리가 티타늄으로 확산되는 속도보다 빠르게 나타났고, 이는 티타늄 나노 박막이 저온 구리 본딩에 효과적임을 보여준다. 12 nm 티타늄 박막은 구리 표면 위에 균일하게 증착되었고, 표면거칠기(R_q)를 4.1 nm에서 3.2 nm로 낮추었다. 티타늄 나노 박막을 이용한 구리 본딩은 200℃에서 1 시간 동안 진행하였고, 이후 동일한 온도와 시간 동안 열처리를 하였다. 본딩 이후 측정된 평균 전단강도는 13.2 MPa이었다.

• 한국전자통신학회논문지
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• 제8권4호
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• pp.549-554
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• 2013

CVD를 이용하여 Cu 시편에 그래핀의 합성을 보이고, Cu 시편의 grain 크기와 방향성에 따른 그래핀의 성장거동을 보이고자 한다. 동일한 온도 및 압력 하에서도 사용하는 분위기 가스의 종류에 따라서 Cu의 확산에 영향을 주게 되고, 그래핀 합성 시 사용되는 $H_2$와 $CH_4$ 가스 분위기 하에서 Cu grain의 성장에도 영향을 미치는 것을 알 수 있었으며, 결과적으로 Cu grain의 성장이 그래핀의 합성과 성장에 직접적인 관련이 있음을 보이고자 하였다. 부식 저항성은 상온에서 동전위 분극실험를 통하여 분석하였으며, 부식속도 비교에서 그래핀 코팅된 Cu 시편의 경우가 그래핀의 화학적 안정성에 기인하여 순수 Cu 시편의 경우보다 동일한 부식 환경에서 약 10배 정도 안정적인 것으로 관찰이 되었다. 또한, grain boundary를 포함, 결함이 없는 그래핀의 균일한 성장의 가능성을 보이고, 이의 합성을 통한 공학적인 활용이 그 최종적인 목적이 될 것이다.

• Journal of Welding and Joining
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• 제13권3호
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• pp.106-115
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• 1995

To know the bonding phenomena of Ti/Cu brazed joint, a characteristic of microstructures in bonding interlayer of vacuum brazed pure Ti to Cu has been studied in the temperature range from 1088 to 1133K for various bonding times using Ag-28wt%Cu filler metal. Also intermediate phases formed in bonded interlayer and behavior of layer growth have been investigated. The obtained results in this study are as follows: 1) Liquid insert metal width at the each brazing temperature was proportional to the square root of brazing time, and it was considered that the liquid insert metal width was controlled by the diffusion rate process of primary .alpha.-Cu formed at the Ti side. 2) Intermediate phases formed near the Ti interface were .betha.-Ti and intermetallic compounds TiCu, Ti$_{2}$Cu, Ti$_{3}$Cu, and TiCu. 3) .betha.-Ti formed in Ti base metal durig brazing transformed to lamellar structure, .alpha.-Ti + Ti$_{2}$Cu. The structure came from the eutectoil decomposition reaction in cooling. And the width of .betha.-Ti layer was proportional to the square root of brazing time, and it was considered that the growth of .betha.-Ti layer was controlled by interdiffusion rate process in .betha.-Ti. 4) The layer growth of TiCu, Ti$_{3}$Cu$_{4}$ and TiCu, phases formed near the Ti interface was linerface was linearly proportional to the brazing time, and it was considered that the layer growth of these phases was controlled by the chemical reaction rate at the interface.

• 전자공학회논문지A
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• 제31A권5호
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• pp.94-100
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• 1994

The junction failure mechanism of W plugs has not been fully understood while the selective W deposition has been widely used for plugging interconnection lines. In this paper, the thermal stability and junction failure mechanism of sub-micron contacts using selective CVD-W plugs were intensively studied with the metal lines of AISiCu, Ti/AISiCu and TiN/AISiCu. The experimental results showed that the contact chain resistance and leakage current in the AISiCu and Ti/AISiCu metallizations were significantly degraded after annealing. From the SEM analysis, it was found that the junction spiking, due to the Al atoms diffusion along the porous interface between selective CVD-W and contactside wall, caused the junction failure. In constast, there was no degradation of the contact resistance and junction leakage current in TiN/AISiCu metal structu-re. It is believed that the TiN barrier layer could prevent AI(Ti) atoms Fromdiffusing. Therefore, TiN barrier between W plug and Al should be used to impro-ve the thermal stability of sub-micron contacts using the selective CVD-W plugs.

• Asian-Australasian Journal of Animal Sciences
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• 제15권7호
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• pp.1057-1065
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• 2002

The antagonistic activities of 30 strains of lactobacilli against Helicobacter pylori were determined and Lactobacillus helveticus CU631 has been selected as the strain which possesses the strongest inhibitory effect in the disc diffusion assay showing inhibition zone diameter of $10{\pm}1.5mm$, whereas those of L. plantarum and L. fermentum have been shown to be $4.0{\pm}0.6mm$. H. pylori G88016 revealed the highest vacuolating toxin producing activity among the 8 strains, the inhibitory activity of L. helveticus CU631 in vacuolating toxin producing activity of H. pylori manifested in the co-culture of two strains and in the 5:5 mixture of supernatant of the two strains. Both L. helveticus CU631 and cell free culture supernatant had a strong inhibitory activities in urease and cytotoxin producing activities of H. pylori NCTC11637 and CJH12. An accelerated proteolytic activity of water soluble peptides by L. helveticus CU631 during the refrigeration storage has been manifested in the cream cheese. DNA seqences of 16S-23S ribosomal RNA spacer region showed typical pattern among the various strains of L. helveticus, which could be used in the identification of L. helveticus CU 631.

• 마이크로전자및패키징학회지
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• 제5권1호
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• pp.7-18
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• 1998

In the flip chip interconnection on organic substrates using eutectic Pb/Sn solder bumps highly reliable Under Bump Metallurgy (UBM) is required to maintain adhesion and solder wettability. Various UBM systems such as 1$\mu$m Al/0.2$\mu$m Pd/1$\mu$m Cu, laid under eutectic Pb/Sn solder were investigated with regard to their interfacial reactions and adhesion proper-ties. The effects of numbers of solder reflow and aging time on the growth of intermetallic compounds (IMCs) and on the solder ball shear strength were investigated. Good ball shear strength was obtained with 1$\mu$m Al/0.2$\mu$m Ti/5$\mu$m Cu and 1$\mu$m Al/0.2$\mu$m ni/1$\mu$m Cu even after 4 solder reflows or 7 day aging at 15$0^{\circ}C$. In contrast 1$\mu$m Al/0.2$\mu$m Ti/1$\mu$m Cu and 1$\mu$mAl/0.2$\mu$m Pd/1$\mu$m 쳐 show poor ball shear strength. The decrease of the shear strength was mainly due to the direct contact between solder and nonwettable metal such as Ti and Al resulting in a delamination. In this case thin 1$\mu$m Cu and 0.2$\mu$m Pd diffusion barrier layer were completely consumed by Cu-Sn and pd-Sn reaction.