目的 研究金属间化合物与 Sn 晶须在 Sn-Cu 薄膜体系中形成的热力学机制。 方法 利用界面热力学理论,通过计算相应的表面能、界面能和临界厚度,研究金属间化合物的形成与 Sn 晶须的生长过程。 结果 金属间化合物 Cu6Sn5 先在 Sn 晶界与 Cu/ Sn 界面交界处形成,然后沿着 Cu/ Sn 界面生长;产生的应力梯度驱动 Sn 原子扩散至表面,形成 Sn 晶须。 结论 Sn 晶须的生长源于 Sn 层中金属间化合物的生成,并由此提出了抑制 Sn 晶须生长的方法。

Objective To investigate the thermodynamic mechanisms of the intermetallic compound (IMC) formation and Sn whisker growth in Sn-Cu bilayer thin film system. Methods Using the interface thermodynamics theory, the IMC formation and the Sn whisker growth were studied through calculating the corresponding surface energies, interface energies and critical thickness. Results The IMC Cu6Sn5 was firstly formed at the triple junction of Sn grain boundary and Sn/ Cu interface and then grew along the Sn/ Cu interface. The resulting stress gradient drove the diffusion of Sn atoms to the surface and formed Sn whisker on it. Conclusion The Sn whisker growth was caused by the IMC formation in Sn sublayer, based on which some methods were proposed for inhibiting the growth of Sn whisker.