The morphology of corrosion pits in sputtered pure aluminum and Al(0.5
wt% Cu) thin film metallizations has been investigated for a diluted
chloride solution. The observed fractal-like patterns show clearly dis
tinct features in ramification and branch density, which can be attrib
uted to microscopic inhomogeneities inside the aluminum film. It is di
scussed how these observations may have an impact on the current descr
iption of diffusion phenomena in thin films, e.g. concerning electromi
gration.