Demonstrating 170°C Low Temperature Cu-In-Sn wafer level Solid Liquid Interdiffusion Bonding
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2022-03-01
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en
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8
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IEEE Transactions on Components, Packaging and Manufacturing Technology, Volume 12, issue 3, pp. 446 - 453
Abstract
The wafer-level Solid Liquid Interdiffusion (SLID) bonds carried out for this work take advantage of the Cu-In-Sn ternary system to achieve low temperature interconnections. The 100mm Si wafers had μ-bumps from 250μm down to 10μm fabricated by consecutive electrochemical deposition of Cu, Sn and In layers. The optimized wafer-level bonding processes were carried out by EV Group and Aalto University across a range of temperatures from 250°C down to 170°C. Even though some process quality related challenges were observed, it could be verified that high strength bonds with low defect content can be achieved even at a low bonding temperature of 170°C with an acceptable 1-hour wafer-level bonding duration. The microstructural analysis revealed that the bonding temperature significantly impacts the obtained phase structure as well as the number of defects. A higher (250°C) bonding temperature led to the formation of Cu3Sn phase in addition to Cu6(Sn,In)5 and resulted in several voids at Cu3Sn|Cu interface. On the other hand, with lower (200°C and 170°C) bonding temperatures the interconnection microstructure was composed purely of void free Cu6(Sn,In)5. The mechanical testing results revealed the clear impact of bonding quality on the interconnection strength.Description
| openaire: EC/H2020/826588/EU//APPLAUSE
Keywords
Bonding, Cu-In-Sn metallurgy, Indium, Low-temperature wafer-level bonding, Packaging, Photomicrography, Silicon, SLID bonding, Surface cracks, Surface morphology
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Vuorinen, V, Ross, G, Klami, A, Dong, H, Paulasto-Kröckel, M, Wernicke, T & Pönninger, A 2022, ' Demonstrating 170°C Low Temperature Cu-In-Sn wafer level Solid Liquid Interdiffusion Bonding ', IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 12, no. 3, pp. 446 - 453 . https://doi.org/10.1109/TCPMT.2021.3111345