Abstract The phase-transformation-induced damage of Cu6Sn5 is an emerging reliability issue in the manufacturing of 3D ICs. Although the retarded phase transformation from η-Cu6Sn5 to η′-Cu6Sn5 at room temperature can produce a large expansion in volume, how the transformation stress threatens the joint reliability during usage is poorly understood. In this paper, the evolution characteristics of quenched η-Cu6Sn5 bumps were observed during ageing at 25 °C for 1–40 d Due to the retarded phase transformation, η′-Cu6Sn5 whiskers spontaneously nucleated and grew on the surfaces of η-Cu6Sn5 bumps. The orientation relationship between the two phases favourable for whisker growth was confirmed, and two necessary conditions for whisker formation were discussed. In addition, the potential harmfulness of whisker growth was analysed. The study will help expose the phase-transformation-induced damage of Cu6Sn5 during room-temperature ageing and may reduce the failure risk of entire Cu6Sn5 intermetallic joints in future large-scale applications of 3D ICs.

中文翻译：

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η-Cu6Sn5金属间化合物室温时效过程中η′-Cu6Sn5晶须的生长演化及形成机制

摘要 Cu6Sn5 的相变引起的损坏是 3D IC 制造中一个新兴的可靠性问题。虽然在室温下从 η-Cu6Sn5 到 η'-Cu6Sn5 的延迟相变会产生较大的体积膨胀，但在使用过程中相变应力如何威胁到接头的可靠性却知之甚少。在本文中，观察了淬火 η-Cu6Sn5 凸点在 25 °C 时效 1-40 d 过程中的演化特征 由于相变延迟，η'-Cu6Sn5 晶须在 η-Cu6Sn5 凸点表面自发成核和生长. 确认了有利于晶须生长的两相之间的取向关系，并讨论了晶须形成的两个必要条件。此外，还分析了晶须生长的潜在危害。