Electromigration Lifetime and Step Coverage in Al/Cu/Si Thin Film Conductors

Electromigration-induced failure was investigated in Al/Cu/Si conductor stripes deposited over trenches cut into an oxide layer and compared with those deposited onto flat areas. The results indicate a reduction in lifetime which is proportional to the size of the step to be covered and this reduction is in excess of what is expected from simple current density scaling. In addition, the electromigration performance of conductors deposited over topology did not correlate well with the performance on flat structures.