微凸点中电迁移与Sn晶粒取向相互作用研究

With the demands of continuous miniaturization and high-performance of electronic devices,electromigration has become a serious reliability issue.This project is intended to make a deep and systematical research on the major scientific issues on the interaction between electromigration and Sn grain orientation, which is involved in the application of micro bumps undergoing electromigration at high current density, i.e., the directionally driven diffusion,the anisotropic characteristics and the diffusion creep mechanism. The in situ electromigration experiments of the line-type interconnects and flip-chip micro bump swere conducted using the electron backscattered diffraction and the synchrotron radiation X-ray microdiffraction,in order to reveal the effect of the Sn grain orientation on the electromigration failure mechanism, clarify the quantitative relationship between the Sn grain orientation and the flux of solute atoms(holes), reveal the driving force ofthe resistance drop andthe Sn grain slip and rotation, elucidate the diffusion creep and deformation coordination mechanisms of the grain slip and rotation,expound the correlate law between the resistance decrease and the grain rotation and slip,characterize the conditions and mechanisms of the Sn grain growth and annexation, reveal the influence of the electromigrationon the reliability and failure of micro bump. Combining the experimental result and the theoretical study, propose the solutions to enhance the reliability of micro bumps;meanwhile,computer simulation is used to provide a scientific guidance for the reliability design of micro bumps.

电子封装技术持续向微型化、高性能发展带来的众多挑战中电迁移已成为一个引人关注的重要的可靠性问题。本项目拟针对微尺度凸点在高电流密度下应用出现的电迁移和Sn晶粒取向之间相互作用所涉及的主要科学问题：定向驱动扩散、各向异性特征、扩散蠕变机制进行系统深入地研究。利用背散射电子衍射与同步辐射X射线微衍射等技术手段，通过原位电迁移实验，对设计的线性焊点和倒装微凸点进行研究，揭示Sn晶粒取向对微凸点电迁移失效的影响机制；确立Sn晶粒取向与溶质原子（空穴）电迁移通量的定量关系；揭示Sn晶粒滑移旋转与电阻下降的驱动力；阐明Sn晶粒滑移旋转的扩散蠕变机理与变形协调机制；阐明Sn晶粒滑移旋转与电阻下降的相关性规律；表征Sn晶粒生长吞并的条件与机制；揭示电迁移对微凸点可靠性和失效机理的影响规律。在理论研究的基础上结合实验提出提高微凸点可靠性的解决方案，辅助以计算机模拟为微凸点连接的可靠性设计提供科学指导。

本项目研究了微尺度凸点在高电流密度下应用出现的电迁移和Sn晶体取向之间相互作用，揭示了Sn晶粒取向对微焊/凸点电迁移失效的影响机制，率先表征了溶质原子扩散行为、阴极溶解、界面间金属化合物的析出行为，阐明了Sn晶粒旋转滑移与晶粒取向的作用关系。代表性成果包括：1）修正的Sn晶体取向与溶质原子（空穴）电迁移通量的定量关系能够统一解释电迁移下阴极基板的溶解行为；2）Sn晶粒取向强烈影响电迁移过程中焊点的失效模式；3）提出了电迁移下Sn晶粒旋转滑移模型。