Microstructure evolution of Ag–8Au–3Pd alloy wire during electromigration

• The activation energy of Ag–8Au–3Pd alloy wire was obtained as 0.61 eV.
• During EM, the silver atoms diffused from negative to the positive terminal on the wire surface.
• The microstructure (grain size and grain boundary) was characterized by FIB-EBSD.
• During EM, the atom transportation was found to cause grain size growth and atom diffusion on the wire surface.

As the continuous shrinkage of the interconnect line width in microelectronics devices, there is a growing concern about the electromigration (EM) failure of bonding wire. In addition, an innovative Ag–8Au–3Pd alloy wire has shown promise as an economical substitute for gold wire interconnects due to the cost pressure of gold in the last decade. In present study of the Ag–8Au–3Pd alloy wire, the surface diffusion occupied the dominant position during EM failure, and the activation energy was found to be 0.61 eV. In order to reveal the failure mechanism, the cross-sections of the Ag–8Au–3Pd alloy wire during EM were prepared by focused ion beam (FIB) micro-machining for electron backscatter diffraction (EBSD) analysis. The microstructure evolution of the Ag–8Au–3Pd alloy wire was characterized by the grain size and grain boundary. As a result, the EM failure originates in the atom transportation, which causes grain size increasing and atom diffusion on the wire surface.