We report the first successful growth of an epitaxial insulator‐metal‐semiconductor structure. The substrate is Si (111), on which a layer of CoSi2followed by a layer of CaF2have been grown by molecular beam epitaxy. The epitaxy of the top CaF2layer improves upon rapid thermal annealing. The epitaxial relations of the two overlayers with respect to the substrate have been determined. The lattice of the CoSi2is rotated 180° with respect to the Si lattice, while the CaF2is aligned with the Si lattice. This work demonstrates that it is possible to combine these materials in a single heteroepitaxial structure and may have important applications in three‐dimensional integration.