Resistance behaviour and morphological changes during electromigration in gold wires

We present in situ scanning electron microscope electromigration measurements on fine-grained gold nanowires. The grain size of 20-40 nm is much smaller than the wire width of similar or equal to 1 mu m. Electrical breakdown occurs in a slit-like manner, which has been observed commonly for bamboo-like or single-crystalline wires. Furthermore, the development of void area is determined and found to increase linearly over time for these polycrystalline wires. Also, the local enhancement of the current density at the position of the critical voids is determined. In addition, calculations of the temperature increase at the position of electrical breakdown reveal a locally reduced energy dissipation belonging to the position with the highest current density.