Epitaxial Ru Nanowire on Single-Crystalline Graphene for Advanced Interconnect Application

In this work, we study epitaxial Ru metallic nanowire on graphene as a model material for future interconnect applications. We first grew epitaxial Ru ultrathin film on single-crystalline, monolayer graphene on SiO2 substrate. We demonstrated fabrication of epitaxial Ru nanowires on graphene using high-resolution H-SiQ ebeam lithography and reaction ion etching techniques. The epitaxial Ru nanowires were prepared using O2/Cl2 dry etching chemistry with ebeam patterned H-SiQ as the etching mask on pregrown Ru thin film. We created epitaxial Ru nanowires with a line height down to 7 nm and a line width down to 26 nm. Electron backscatter diffraction characterization confirms that the epitaxial Ru nanowires maintain a single-crystalline structure. Focused ion beam milling reveals the rectangular shape of the nanowire cross sections. We measured the electrical resistivity of Ru nanowires fabricated on both graphene and bare SiO2 substrates with line widths ranging from ∼26 nm to ∼200 nm and line height ranging from ∼7 nm to ∼19 nm. We confirmed that epitaxial Ru nanowires grown on graphene have significantly lower resistivity (∼13% to ∼38% reductions) than polycrystalline Ru nanowires grown on bare SiO2 substrate with similar cross-section areas which is due to better crystalline quality and reduced electron grain boundary scattering.