• 마이크로전자및패키징학회지
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• 제19권2호
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• pp.35-39
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• 2012

플립칩 접합시 발생하는 계면반응 거동과 접합특성을 계면에 생성되는 금속간화합물의 관점에서 접근하였다. 이를 위하여 Al/Cu와 Al/Ni의 under bump metallization(UBM) 층과 Sn-Cu계 솔더(Sn-3Cu, Sn-0.7Cu)와의 반응에 의한 금속간화합물의 형성거동 및 계면접합성을 분석하였다. Al/Cu UBM 상에서 Sn-0.7Cu 솔더를 리플로우한 경우에는 솔더/UBM 계면에서 금속간화합물이 형성되지 않았으며, Sn-3Cu를 리플로우한 경우에는 계면에서 생성된 $Cu_6Sn_5$ 금속간화합물이 spalling 되어 접합면이 분리되었다. 반면에 Al/Ni UBM 상에서 Sn-Cu계 솔더를 리플로우한 경우에는 0.7 wt% 및 3 wt%의 Cu 함량에 관계없이 $(Cu,Ni)_6Sn_5$ 금속간화합물이 계면에 형성되어 있었으며, 계면접합이 안정적으로 유지되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.53-53
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• 2011

As the dimension of Cu interconnects has continued to reduce, its resistivity is expected to increase at the nanoscale due to increased surface and grain boundary scattering of electrons. To suppress increase of the resistivity in nanoscale interconnects, alloying Cu with other metal elements such as Al, Mn, and Ag is being considered to increase the mean free path of the drifting electrons. The formation of Al alloy with a slight amount of Cu broadly studied in the past. The study of Cu alloy including a very small Al fraction, by contrast, recently began. The formation of Cu-Al alloy is limited in wet chemical bath and was mainly conducted for fundamental studies by sputtering or evaporation system. However, these deposition methods have a limitation in production environment due to poor step coverage in nanoscale Cu metallization. In this work, gap-filling of Cu-Al alloy was conducted by cyclic MOCVD (metal organic chemical vapor deposition), followed by thermal annealing for alloying, which prevented an unwanted chemical reaction between Cu and Al precursors. To achieve filling the Cu-Al alloy into sub-100nm trench without overhang and void formation, furthermore, hydrogen plasma pretreatment of the trench pattern with Ru barrier layer was conducted in order to suppress of Cu nucleation and growth near the entrance area of the nano-scale trench by minimizing adsorption of metal precursors. As a result, superconformal gap-fill of Cu-Al alloy could be achieved successfully in the high aspect ration nanoscale trenches. Examined morphology, microstructure, chemical composition, and electrical properties of superfilled Cu-Al alloy will be discussed in detail.

• Journal of Magnetics
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• 제18권2호
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• pp.81-85
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• 2013

We investigate the electronic and magnetic properties in Cu-doped InN with the N vacancy ($V_N$) from first principles calculations. There is the long-range ferromagnetic order between two Cu atoms, attributed to the hole-mediated double exchange through the strong p-d interaction between the Cu atom and neighboring N atom. The system of $V_N$ defect in Cu-doped InN has the lowest formation energy. Due to the hybridization between the Cu-3d and $V_N$ states, the spin-polarization on the Cu atoms in the InN lattice is reduced by $V_N$ defect. So, it shows a weak ferromagnetic behavior.

• 한국분말재료학회지
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• 제9권5호
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• pp.329-335
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• 2002

Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using $WO_3-CuO$ mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in $H_2$ atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.133-137
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• 2003

The effect of Bi additions to the eutectic Sn-3.5Ag solder alloy on the growth kinetics of the intermetallic compound (IMC) layers during solid-state aging of Sn-Ag-Bi/Cu solder joints has been Investigated. The Bi additions enhanced the growth rate of the total IMC layer comprising of $Cu_6Sn_5$ and $Cu_3Sn$ sublayers. This enhanced IMC growth rate was primarily due to the rapid increase In the growth rate of $Cu_6Sn_5$ sublayer. The growth rate of $Cu_3Sn$ sublayers was little influenced and appeared to be retarded by the Bi additions. The observed growth behavior of $Cu_6Sn_5$ and $Cu_3Sn$ sublayers could be understood if the interfacial reaction barrier at the $Cu_6Sn_5/solder$ interface were reduced by the segregation of Bi at the interface.

• Applied Microscopy
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• 제26권2호
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• pp.235-241
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• 1996

Amophization and decomposition behaviour in $Mg_{62}Cu_{26}Y_{12}$ alloy prepared by melt spinning method and wedge type metal mold casting method have been investigated by a detailed transmission electron microscopy. Amorphous phase has formed in melt-spun ribbon. In the case of the wedge type specimen, however, the amorphous phase has formed only around the tip area within about 2 mm thickness. The remaining part of the wedge type specimen consists of crystalline phases, $Mg_{2}Cu\;and\;Cu_{2}Y$. The supercooling for crystallization behaviour of the amorphous $Mg_{62}Cu_{26}Y_{12}$ alloy, ${\Delta}T_x$ has been measured to be about 60 K. Such a large undercooling of the crystallization bahaviour enables formation of the amorphous phase in the $Mg_{62}Cu_{26}Y_{12}$ alloy under the cooling rate of $10^{2}K/s$. The amorphous $Mg_{62}Cu_{26}Y_{12}$ has decomposed into crystalline phases, $Mg_{2}Cu\;and\;Cu_{2}Y$ after heat treatment at $170^{\circ}C\;and\;250^{\circ}C$.

• 한국진공학회지
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• 제10권4호
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• pp.403-410
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• 2001

본 연구에서는 차세대 Cu 박막 증착 방법으로 유망한 CVD(chemical vapor deposition)방법으로 실질적 배선 증착 공정과 동일하게 시행하여 여러 조건에서 Cu를 증착하여 가장 EM에 관하여 높은 내구성을 가지는 조건을 알아보고 또한 박막의 미세구조가 EM에 어떠한 영향을 미치는지를 알아보았으며 MOCVD 방식으로 증착한 Cu박막의 표면과 barrier layer인 TiN과의 응력(stress)을 조사하여 차세대 EM모델인 grain boundary grooving 모델에 실질적으로 적용하였다. 또한, 이러한 실험을 행 한 후에 정확한 EM 현상을 관찰하고 분석하여 반도체 소자의 신뢰성과 성능개선, 결함 예측, 그리고 소자의 배선설계에 중요한 정보를 제공할 것이다. 또한, 보다 우수한 EM 특성을 가질 수 있게 하기 위해 barrier layer위에 Cu와의 접착력(adhesion)을 향상시킬 수 있는 promoter로 Al을 이용하여 얇게 증착한 후 EM축적 파괴 실험을 하여 EM에 대한 높은 저항성을 실질적으로 가질 수 있는지에 대한 실험도 병행하였다.

• 한국재료학회지
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• 제9권4호
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• pp.335-340
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• 1999

The hot cracking phenomena and phase behaviors during hot working process of Cu-Ni bearing hot rolled steels were investigated by a $90^{\circ}$bending tests, BSE image analysis and EDS analysis. For aNi-free 1.2% Cu bearing steel, the surface hot cracking occurred about $1100^{\circ}C$ due to a liquid state Cu-enriched phase formed continuously at the interface between oxide scale and matrix. The liquid Cu-enriched phase penetrated into austenite grain boundaries and caused surface cracking during the hot working. In case of 0.6% Ni containing 1.2% Cu-Ni bearing steel, solid state Cu-Ni-riched phase existed at the scale/matrix interface as a discontinuous type. But the higher addition of 1.2% Ni, solid state Ni-Cu-riched phase was formed dominantly in the oxide scale. It was found that the addition of Ni suppressed the surface cracking of 1.2% Cu bearing steel by eliminating the liquid state Cu-enriched phase.

• 전기화학회지
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• 제20권1호
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• pp.1-6
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• 2017

본 연구에서는 구리 배선 공정에서 구리 씨앗층 표면에 형성되는 구리 자연산화물을 제거하는 표면 전처리가 후속 구리 전착에 미치는 영향을 살펴보았다. 구리 배선 공정의 화학적 기계적 연마 공정에서 사용하는 citric acid 기반의 용액을 구리 표면 전처리 과정에 적용하여 표면에 존재하는 구리 자연 산화물을 제거하였고, 용액 조성 변화를 통해 산화물 제거의 선택성을 높여 구리 씨앗층의 손실을 최소화하였다. 또한 표면 전처리 후 구리 전해 전착과 무전해 전착을 시도하여 전착한 박막의 비저항, 표면 거칠기 등의 성질을 비교하고, 이를 통해 선택적으로 구리 산화물을 제거한 이후에 전착된 박막의 비저항과 표면 거칠기가 가장 낮게 나타남을 확인하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.97-97
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• 2017

This study investigated the corrosion protection by electrodeposited copper layer on AZ31 Mg alloy with and without additional silver layer by immersion test, salt spray test, OCP transient and potentiodynamic polarization experiment. The single electrodeposited Cu layer on AZ31 Mg alloy showed a nodular structure with many imperfections of crevices between the nodules, which resulted in the fast initiation of pitting corrosion within first few hours of immersion. Double-layer coating of Cu and outer Ag layer slightly increased the initiation time for pitting corrosion. Triple-layer coatings of Cu/Ag/Cu exhibited the most efficient corrosion protection of AZ31 Mg alloy, compared to the single- and double-layer coatings. Surface morphology of the outer Cu layer in the triple-layer was changed from the nodular structure to fine particle structure with no crevices due to the presence of an additional Ag layer. Thus, the improved corrosion resistance of AZ31 Mg alloy by electrodeposited Cu/Ag or Cu/Ag/Cu layers is readily ascribed to the decreased number of imperfections in the electrodeposited layers due to the additional silver layer. It is concluded that the additional silver layer provides many nucleation sites for the second Cu plating, resulting in the formation of finer and denser structure than the first Cu electrodeposit.