Electromigration in 2 μm Redistribution Lines and Cu-Cu Bonds with Highly <111>- oriented Nanotwinned Cu

In this paper, we adopted highly <;111>-oriented nanotwinned Cu (nt-Cu) to fabricate 2-μm-wide redistribution lines (RDLs) capped with polyimide and 30-um Cu-Cu direct bonds, and then measured their electromigration (EM) lifetimes. The results show that the nt-Cu RDLs possessed a higher EM lifetime than regular Cu RDL lines. Serious oxidation was observed in the Cu lines after the EM tests. For the EM in Cu-Cu bonds, the resistance Cu-Cu bumps increased less than 5% after 1000 h under 2×10
⁵
A/cm
²
at 150°C.