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 SiO 2 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 O 2 /Cl 2 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 SiO 2 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 SiO 2 substrate with similar cross-section areas which is due to better crystalline quality and reduced electron grain boundary scattering.