Dependence of intermetallic compound formation on the sublayer stacking sequence in Ag–Sn bilayer thin films

Rossi, Paul; Zotov, Ν.; Bischoff, E.; Mittemeijer, E. J.

doi:10.1016/j.actamat.2015.09.042

Cited by 20 publications

(8 citation statements)

References 40 publications

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“…3a. At this stage, Ag 3 Sn IMCs could be formed partially after the deposition of the 3 rd Ag layer, because Ag–Sn is one of the fast interdiffusion couples with a mean interdiffusion coefficient of 10 −13 cm 2 /s at room temperature 21,22 . Subsequently, as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Reliable low-temperature die attach process using Ag/Sn/Ag sandwich structure for high-temperature semiconductor devices

Choi

Choi²,

2019

Sci Rep

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A low-cost and eco-friendly die attach process for high temperatures should be developed owing to the expansion of the field of high-temperature applications, such as high-power and high-frequency semiconductors. Pb-based and Au-based systems have been used as conventional die attach materials for high-temperature devices. However, these materials exhibit environmental problems and are expensive. Here, we show that the die attach process using the backside metal of the Ag/Sn/Ag sandwich structure is successfully developed for the mass production of Si devices. It has a low-temperature bonding process (235 °C), a high remelting temperature (above 400 °C), and rapid bonding time (20 ms). In addition, it exhibits better properties than Au-12Ge and Pb-10Sn backside metals, which are conventional materials for the high-temperature die attach process. After the die bonding process, various reliability tests of Si devices with the Ag/Sn/Ag backside metal structure were performed.

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Section: Resultsmentioning

confidence: 99%

Reliable low-temperature die attach process using Ag/Sn/Ag sandwich structure for high-temperature semiconductor devices

Choi

Choi²,

2019

Sci Rep

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“…25 Eq. (7) yields a value of 27 MPa using the elastic constants and thermal expansion coefficients listed in Ref.…”

Section: Stress Development In the Ag Layermentioning

confidence: 99%

“…Similar reasoning was also used to explain the results obtained upon IMC formation in the Ag-Sn system. 25 Additionally, it seems possible that nucleation of the AgIn 2 IMC is associated with a smaller nucleation barrier, as compared to nucleation of the Ag 2 In IMC: (i) the volume per mole In is larger in case of the Ag 2 In IMC 33 as compared to the AgIn 2 IMC, 34 while both values are larger than the molar volume of the In layer. 42 It follows that the volume misfit upon IMC formation inside the In layer is larger in case of the Ag 2 In IMC compared to the AgIn 2 IMC, favoring initial formation of AgIn 2 inside the original In layer; (ii) further Ag 2 In has a much more complex crystal structure: the AgIn 2 IMC has an ordered tetragonal structure (space group I4=mcm, CuAl 2 -type) with 12 atoms per unit cell occupying 2 different Wyckoff positions, 34 whereas Ag 2 In has an ordered cubic structure (space group P 43m, Cu 9 Al 4 -type) with 52 atoms per unit cell occupying 8 different Wyckoff positions.…”

mentioning

confidence: 99%

“…A similar observation was also made and explained for the case of Ag-Sn bilayers. 25 Therefore "In on top of Ag" type bilayers were chosen for the evaluation of the kinetics of IMC formation, as the presence of only one IMC in the as-deposited state allows a more straightforward analysis of the kinetics of IMC formation (cf. Section III B).…”

Section: A Microstructure and Phase Constitutionmentioning

confidence: 99%

“…The same observation has already been made for the Ag-Sn system. 25 In the present case, only the results from bilayers with In on top of Ag are discussed, where cases of simultaneous, mixed interface-diffusion-controlled growth and pure diffusioncontrolled growth could be identified. Interdiffusion coefficients in the Ag-In system were derived on the basis of the values for the growth constants of the Ag 2 In IMC at various temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of intermetallic compound formation in thermally evaporated Ag-In bilayers

Rossi

Zotov

Mittemeijer

2016

Journal of Applied Physics

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The kinetics of intermetallic compound (IMC) formation in thermally evaporated Ag-In bilayers, with In on top of Ag, was investigated using X-ray diffractometry, applied to the surfaces of the bilayer specimens, as well as scanning electron microscopy, applied to cross-sections of the bilayer specimens, prepared by a focused ion beam instrument. IMC formation was followed at room temperature as well as at elevated temperatures of 50 °C, 60 °C, and 70 °C. Two distinct growth regimes were observed coinciding with the availability of pure In. The AgIn2 IMC nucleated initially, followed by nucleation of the Ag2In IMC. The growth of AgIn2 was found to be controlled by both diffusional processes as well as interfacial reactions. The growth of the Ag2In IMC is dominantly diffusion-controlled. An interdiffusion coefficient of D=1.1±3.9·10−4 cm2 s−1 exp(−60.5±9.2 kJ mol−1R−1T−1) was obtained for the Ag2In IMC. The observations were discussed in terms of the interplay of thermodynamic and kinetic constraints.

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Facile Synthesis of Conductive Flexible Composite Sn@Ag Microspheres and their Application in Anisotropic Conductive Films

Zhang

Peng

et al. 2021

Part & Part Syst Charact

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Composite microspheres with noble metal nanoshells are advantageous in flexible circuit connections, flip chips, and chemical sensors. It is difficult for Polystyrene microspheres to cover a complete Ag layer, and hard metal microspheres have no deformability. These two reasons have contributed to this research. This report demonstrates a facile synthesis route that chemically deposits an Ag layer on the surface of 30 µm Sn microspheres to form a composite Sn@Ag double‐layer structure, which is suitable for anisotropic conductive films (ACFs) with linewidths greater than 100 µm. Scanning electron microscope analysis reveals that the surface Ag coating thickness can be controlled within the range of 737 nm–5.62 µm by varying the amount of Ag source applied, and trace free Ag particles are produced during the preparation process. An anisotropic conductive adhesive film is successfully fabricated and hot‐pressed after the film‐on‐film flexible circuit board. The microspheres form an ACF single‐layer structure after hot pressing. Hot pressing in the range of 10–20 MPa can ensure deformation and avoid Ag shell cracking, and the deformation is determined when Sn@Ag is in contact with the circuit surfaces at both ends. This approach provides a potential method of preparing low‐cost and high‐performance ACFs.

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Dependence of intermetallic compound formation on the sublayer stacking sequence in Ag–Sn bilayer thin films

Cited by 20 publications

References 40 publications

Reliable low-temperature die attach process using Ag/Sn/Ag sandwich structure for high-temperature semiconductor devices

Reliable low-temperature die attach process using Ag/Sn/Ag sandwich structure for high-temperature semiconductor devices

Kinetics of intermetallic compound formation in thermally evaporated Ag-In bilayers

Facile Synthesis of Conductive Flexible Composite Sn@Ag Microspheres and their Application in Anisotropic Conductive Films

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