Epitaxial growth and characterization of Cu single crystalline films suitable for creation of ballistically conducting nanojunctions

Continued downscaling of Cu nanostructures relevant to CMOS interconnects has been impractical due to resistivity size effects, which result in competitively disadvantageous wire conductance relative to other metals below device length scales of ~10 nm size. Recent publications by our group have shown an ability to controllably minimize grain boundary and surface scattering contributions to resistivity measured through epitaxially grown Ru/Al₂O₃(0001). Moreover, unpublished work by our group now suggests evidence of ballistic conduction through ~100 nm long nanowire devices lithographically produced from such sheets. A similar approach might be expected to allow for ballistic transport through longer devices as a result of improved mean free path for electron scattering through copper vs. ruthenium. This presentation provides results obtained from Cu films grown on MgO(100) and CaF₂(100). MgO-supported film growth is done at the wafer scale using approaches already established at smaller scales under better controlled conditions, while CaF₂ studies will be completed in situ within a UHV surface-science chamber. Key results includes: film thickness and structure characterization (XRR, XRD, and LEED), chemical-state analysis (XPS) and sheet resistance measurements as a function of deposition and processing conditions.