Real-time x-ray microbeam characterization of electromigration effects in Al(Cu) wires

We report real-time, in situ x-ray microbeam measurements of electromigrati on-induced Cu redistribution, and the concurrent local stress variation in Al(Cu) wires. The data, which were obtained by combining x-ray microtopogra phy with energy-dispersive fluorescence analysis, encompass both the early and late stages of electromigration as well as the postrelaxation stage at high temperature with the current turned off. We observe that both Cu conce ntration and stress values show unexpected local variations that may reflec t the effect of local configuration such as film-substrate interface integr ity or microstructure. (C) 2001 American Institute of Physics.