  This paper demonstrates eigenanalysis to quantitatively reveal the diversity
and capacity of identities offered by the morphological diversity in silicon
nanostructures formed via random collapse of resist. The analysis suggests that
approximately 10^115 possible identities are provided per 0.18-um^2 area of
nanostructures, indicating that nanoscale morphological signatures will be
extremely useful for future information security applications where securing
identities is critical. The eigenanalysis provides an intuitive physical
picture and quantitative characterization of the diversity of structural
fluctuations while unifying measurement stability concerns, which will be
widely applicable to other materials, devices, and system architectures.
