• 마이크로전자및패키징학회지
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• 제20권3호
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• pp.45-51
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• 2013

3차원 적층 패키지를 위한 Cu/Sn-3.5Ag 미세범프의 솔더 구조에 따른 금속간화합물 성장거동을 분석하기 위해 솔더 두께가 각각 $6{\mu}m$, $4{\mu}m$인 서로 다른 구조의 미세범프를 $130^{\circ}C$, $150^{\circ}C$, $170^{\circ}C$ 조건에서 실시간 주사전자현미경을 이용하여 실시간 금속간화합물 성장 거동을 분석하였다. Cu/Sn-3.5Ag($6{\mu}m$) 미세범프의 경우, 많은 양의 솔더로 인해 접합 직후 솔더가 넓게 퍼진 형상을 나타내었고, 열처리 시간경과에 따라 $Cu_6Sn_5$ 및 $Cu_3Sn$금속간화합물이 성장한 후, 잔류 Sn 소모 시점 이후 $Cu_6Sn_5$가 $Cu_3Sn$으로 상전이 되는 구간이 존재하였다. 반면, Cu/Sn-3.5Ag($4{\mu}m$) 미세범프의 경우, 적은양의 솔더로 인해 접합 직후 솔더의 퍼짐 현상이 억제 되었고, 접합 직후 잔류 Sn상이 존재하지 않아서 금속간화합물 성장구간이 억제되고, 열처리 시간경과에 따라 $Cu_6Sn_5$가 $Cu_3Sn$으로 상전이 되는 구간만 존재하였다. 두 시편의 $Cu_3Sn$상의 활성화 에너지의 값은 Cu/Sn-3.5Ag($6{\mu}m$) 및 Cu/Sn-3.5Ag($4{\mu}m$) 미세범프가 각각 0.80eV, 0.71eV로 나타났고, 이러한 차이는 반응기구 구간의 차이에 따른 것으로 판단된다. 따라서, 솔더의 측면 퍼짐 보다는 접합 두께가 미세범프의 금속간화합물 반응 기구를 지배하는 것으로 판단된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 춘계학술대회 논문집
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• pp.84-89
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• 1996

The nucleation and growth of microporosities was observed during the course of annealing treatment of sputter-deposited AgInSbTe thin films. There was a close correlation between the density of microporosity and the sputtering gas pressure in annealed thin films. The void density for a given composition decreased with sputtering gas pressure. It was shown from the present study that the number of porosities decreased while the average porosity size increased as the annealing temperature and holding time increased. The mechanism of porosity formation in the sputter-deposited AgInSbTe thin flus containing Ar-impurity trapped from the Ar-plasma is discussed in the present article.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
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• pp.120-122
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• 1994

We examined the magnetic properties as a function of annealing temperature of the as-quenched $Fe_{87}Zr_{7}B_{5}Ag_{1}$ amorphous alloy. The values of $H_{c}$=30m0e, $B_{a}$=0.44T and ${\mu}$i=146000 at $300^{\circ}C$ annealing treatment are obtained. The excel lent soft magnetic properties seem to result from the annihilation of quenching-Induced internal stress by the heat treatment and the change of microstructure due to the different relaxation behavior owing to adding insoluble element such as Ag. Therefore, the $Fe_{87}Zr_{7}B_{5}Ag_{1}$ amorphous alloy is quite promising for practical use as a core material in various transformers of high transformers of high frequency.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.140-140
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• 2000

The initial growth mode of Nb on Ag(11) in sub-monolayer regime and the influence of subsequent 520K annealing are studied using UHV Scanning Tunneling Microscopy. E-beam evaporated Nb is deposited onto the substrate at RT, and STM measurements are carried out at RT and 78 K. With Nb being immiscible in bulk Ag, 3D islands formation begins at early stage and no particular ordered structure is found. After annealing to 520K, most of islands are disappeared from terrace. There exist 2 possibilities. : (1) Diffusion of Nb into the 2nd or 3rd layer of Ag substrate or (2) agglomeration of Nb on Ag at higher temperature. A model will be given to explain the evidence. In addition, we investigated the change of STM image according to bias voltage depending on island size. Possible physical mechanism responsible for such behavior together with interaction between Nb islands and reactive gases will be also discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.157-157
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• 2010

Vertical-structure light-emitting diodes (V-LEDs) by laser lift-off (LLO) have been exploited for high-efficiency GaN-based LEDs of solid-state lightings. In V-LEDs, emitted light from active regions is reflected-up from reflective ohmic contacts on p-GaN. Therefore, silver (Ag) is very suitable for reflective contacts due to its high reflectance (>95%) and surface plasmon coupling to visible light emissions. In addition, low contact resistivity has been obtained from Ag-based ohmic contacts annealed in oxygen ambient. However, annealing in oxygen ambient causes Ag to be oxidized and/or agglomerated, leading to degradation in both electrical and optical properties. Therefore, preventing Ag from oxidation and/or agglomeration is a key aspect for high-performance V-LEDs. In this work, we demonstrate the enhanced thermal stability of Ag-based Ohmic contact to p-GaN by reducing the thermal compressive stress. The thermal compressive stress due to the large difference in CTE between GaN ($5.6{\times}10^{-6}/^{\circ}C$) and Ag ($18.9{\times}10^{-6}/^{\circ}C$) accelerate the diffusion of Ag atoms, leading to Ag agglomeration. Therefore, by increasing the additional residual tensile stress in Ag film, the thermal compressive stress could be reduced, resulting in the enhancement of Ag agglomeration resistance. We employ the thin Ni layer in Ag film to form Ni/Ag mutli-layer structure, because the lattice constant of NiO ($4.176\;{\AA}$ is larger than that of Ag ($4.086\;{\AA}$). High-resolution symmetric and asymmetric X-ray diffraction was used to measure the in-plane strain of Ag films. Due to the expansion of lattice constant by oxidation of Ni into NiO layer, Ag layer in Ni/Ag multi-layer structure was tensilely strained after annealing. Based on experimental results, it could be concluded that the reduction of thermal compressive stress by additional tensile stress in Ag film plays a critical role to enhance the thermal stability of Ag-based Ohmic contact to p-GaN.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.13-16
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• 2000

In this study, we have fabricated nonequilibrium $Fe_{85.6}Zr_{3.3}B_{5.7}Ag_{5.4}$ thin film, which contains an additional insoluble element Ag, by using DC magnetron sputtering method. We have investigated the magnetic properties of amorphous $Fe_{85.6}Zr_{3.3}B_{5.7}Ag_{5.4}$ thin film as a function of rotational field annealing(RFA). After deposition, the amorphous $Fe_{85.6}Zr_{3.3}B_{5.7}Ag_{5.4}$ thin film annealed by rotational field annealing method at $350^{\circ}C$ for an hour was founded to have high permeability of 8680 of 100 MHz, 0.2 mOe, low coercivity of 0.86 De and very low core loss of 1.3 W/cc at 1 MHz, 0.1T.

• Journal of Magnetics
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• 제18권4호
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• pp.412-416
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• 2013

FePt:Ag (100 nm) nanocomposite thin films were prepared on naturally-oxidized Si substrates by dc magnetron sputtering at room temperature. X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to investigate the effects of annealing pressures on the ordering processes and microstructures of these films. The average sizes for the $L1_0$ ordered domains and the FePt grains are reduced to d = 9 nm and D = 13 nm from d = 19 nm and D = 34 nm, respectively, when the annealing pressure is enhanced to 0.6 GPa from room pressure at 873 K. Furthermore, the size distribution is improved into a narrow range. With increasing pressure, the coercivity of $L1_0$-FePt:Ag thin films decreases from 15.1 to 7.6 kOe. In the present study, the effects of high pressure on the $L1_0$ ordering processes and microstructures of FePt:Ag nanocomposite films were discussed.

• 대한금속재료학회지
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• 제50권10호
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• pp.775-783
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• 2012

The effect of thermal annealing on the in-situ growth characteristics of intermetallics (IMCs) and the mechanical strength of Cu pillar/Sn-3.5Ag microbumps are systematically investigated. The $Cu_6Sn_5$ phase formed at the Cu/solder interface right after bonding and grew with increased annealing time, while the $Cu_3Sn$ phase formed at the $Cu/Cu_6Sn_5$ interface and grew with increased annealing time. IMC growth followed a linear relationship with the square root of the annealing time due to a diffusion-controlled mechanism. The shear strength measured by the die shear test monotonically increased with annealing time. It then changed the slope with further annealing, which correlated with the change in fracture modes from ductile to brittle at a critical transition time. This is ascribed not only to the increasing thickness of brittle IMCs but also to the decreasing thickness of the solder, as there exists a critical annealing time for a fracture mode transition in our thin solder-capped Cu pillar microbump structures.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.105-108
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• 2003

Long length of Bi-2223 superconducting wires were fabricated by stacking, drawing process with different precursor owders and different heat-treatment histories. The precursor powders were 2 kinds of Pb content. And a part of the tapes were experienced pre-annealing process which caused tetragonal structure of Bi-2212 phase to orthorhombic structure of it was during drawing process. We confirmed the transformation of Bi-2212 phase from tetragonal structure to orthorhombic structure and reduction of second phases. We designed and made a continuous Ic measurement system for Bi-2223/Ag HTS tape. We could achieve best Ic of 65 A at the Bi-2223/Ag tape using low Pb content of precursor powder and experienced pre-annealing process.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.72-74
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• 2003

We fabricated textured Ag substrates for coated conductor and evaluated the effects of annealing temperature on microstructural evolution, texture formation, and surface morphology. A strong {110}〈110〉 textured Ag substrate was obtained by cold rolling and annealing at 80$0^{\circ}C$: the full-width at half-maximum(FWHM) value of {110}〈110〉 poles was as sharp as 10$^{\circ}$. Surface morphology was evaluated by using Atomic force microscopy(AFM). Root-mean-square(RMS) roughness of the substrate annealed at 80$0^{\circ}C$ was 39.2 nm. The substrate of strong texture and smooth surface, fabricated in our study, is considered to be suitable for use as a substrate for deposition of superconductor films.