Novel carbon-cage-based ultralow-k materials: Modeling and first experiments

A new class of materials is presented that is supposed to be a potential candidate for isolating ultra low-k thin films between metal on-chip interconnects in future CMOS technology nodes. The ideal structure of the novel carbon-cage-based materials is described by a model that assumes an ordered network (mosaic structure) with fullerenes (C60) as the nodes and linker molecules along the edges of the mosaic cells. The interior of the network represents a nanopore of a 1-nm scale. According to the molecular design-based model, structures with simple cubic and diamond-like topology of the network are considered promising candidates. A dielectric constant (k value) of 1.7 and an elastic bulk modulus of about 20 GPa are predicted of ideal combinations of network topology and linker molecules. First experimental results, based on electron energy loss spectroscopy, X-ray absorption spectroscopy, nanoindentation, and atomic force microscopy are presented. A more controlled film fabrication process is needed to get more homogeneous thin films with characteristic material parameters as predicted by the model.