Copper replaced aluminum nearly two decades ago as interconnect material in integrated circuit manufacturing due to its better electrical conductivity. The size of the interconnect wire has been steadily decreasing as Moore’s law has been progressing through various feature size generations. The diameter of the interconnect structure is further expected to decrease as silicon technology is poised to march through a few more generations. Alternatives to copper have been reported—notably, materials such as carbon nanotubes. Their success has been limited, and carbon nanotubes have not been integrated into manufacturing practice.
In this work, copper oxide nanowires (CuO and Cu2O) were produced from copper film, foil, or millimeter-sized wires commercially available, through oxidation using a vapor phase technique. Copper oxide nanowires are grown from conventional bulk copper wires by thermal oxidation. Both CuO and Cu2O nanowires are produced first on Cu substrate in a simple quartz tube furnace system using the most basic and primary methods of oxidation and reduction mechanisms. Oxidation is performed in ambient air, then oxide nanowires are reduced to copper nanowires in the same furnace under a hydrogen flow at 400 °C. The reduction process effectively transforms the oxide nanowires into metallic copper nanowires. The process is amenable to integration into the silicon manufacturing line.