Improving electromigration resistance of fine‐pitch redistributed layer (RDL) using graphene doped twinned copper composites

The electromigration(EM) behavior of graphene‐doped twinned copper composite (GC‐Cu) and nanotwinned copper (NT‐Cu) redistributed layers (RDLs) were investigated. Firstly, it was found that the GC‐Cu has a longer lifetime under various test conditions. For example, the GC‐Cu RDL took 291h to reach a 20% resistance increase, while the NT‐Cu RDL took 117h under the same condition of 120 °C and 10 6 A cm ‐2 . Secondly, the failure mode of EM test were observed, while the microstructural evolution under high temperature storage was served as comparison. The thinner oxidation layer and slighter voiding phenomena were detected on the surface of GC‐Cu RDLs. When the line width and spacing (L/S) of RDL decreased from 20/20 μm to 10/10 μm, new failure modes, i.e. fracture of oxide layer, separation between the oxide layer and copper matrix were also detected, demonstrating the increasing thermal mismatch. Combined with the finite element analysis (FEA), there is simultaneous current aggregation and stress concentration around the voids, which should be the most important factor that causes the degradation of RDL. Above all, this study demonstrated the high EM performance of novel GC‐Cu material, which should give insights into the material design in the fine‐pitch RDL structure and helps to develop the advanced packaging technology. This article is protected by copyright. All rights reserved.