  We study the aggregation transition of a finite theta-polymer system in
dependence on the bending stiffness $\kappa$ with the help of parallel
multicanonical simulations. In order to distinguish amorphous aggregates from
polymer bundles we introduce an order parameter, measuring the correlation of
the end-to-end vectors. With the help of this order parameter, we construct
generic $T$-$\kappa$ phase diagrams for systems with $2$ and $8$ polymers and
discuss the occurring phases from amorphous aggregates to bundle structures.
For an intermediate stiffness range we find multiple aggregated phases which
change with increasing number of polymers and discuss their nature with the
help of microcanonical analyses. We show that the stiffness of semiflexible
theta polymers is the distinguishing parameter for the emergent structural
motifs.
