The Influence of Full IMC Structure on Micro-Bump EM Performance

To fulfill the continuously increasing demand of high-power applications, advanced package technologies were applied to miniature the package form factors. However, the shrinkage in joint dimension and the increase in input power would aggregate the electromigration behaviors and cause reliability concern. In this study, we investigated the electromigration (EM) performance of both Cu/Sn microbump and Cu/Ni/Sn/Cu microbump in full IMC structure. Thus, the results of our electromigration tests revealed that the full IMC structure demonstrated superior EM reliability. The main failure mode observed in the full IMC structure was related to aluminum (Al) trace failure, which was attributed to the electromigration of Al atoms. This finding underscores the importance of forming full IMC joints to enhance the reliability of microbumps in high-performance computing (HPC) applications. Besides, the microstructure evolution of both Cu/Sn microbump and Cu/Ni/Cu/Sn microbump during EM testing have been well investigated.