We have previously shown greatly enhanced resistance to stressinduced hillock formation through fluorine incorporation in aluminum films. Utilizing relatively low F incorporation (<0.1 atomic %), hillock formation density is reduced ∼10x over pure or similarly Cu-doped aluminum films. Electromigration tests were performed on a matrix of structures with varying topology (step heights and slopes) and fluorine incorporation dose. We find that although F improves the stress-induced hillock formation by an order of magnitude, the electromigration performance of flat structures is only slightly improved with F incorporation. Analyzing various step heights and step slopes, the nonfluorinated Al experienced a decreasing electromigration lifetime with increasing step height. However, the optimally implanted F samples showed almost no lifetime reduction with step coverages over a similar regime. In addition, scanning electron micrographs of the failed samples revealed that the failures of the fluorinated samples differ markedly from the non-fluorinated samples. Finally, SIMS profiles taken on F and Cu (for comparison) implanted samples reveal the fundamentally different nature of the two beneficial components: Cu redistributes relatively easily throughout the Al film to segregate to grain boundaries. In contrast, the F profile is extremely stable with simnilar anneals and provides its beneficial effect by forming a distributed refractory metal-like structure within the interconnect.