Integration and Electrical Properties of Carbon Nanotube Array for Interconnect Applications

Carbon nanotube (CNT) vertical integration and electrical properties are presented in full 6-inch wafer for interconnect applications. Series array of 1000 vias made of vertically grown CNTs is obtained with uniform electrical resistances within the wafer. Integration processes are implemented by following sequential steps: bottom electrode and via hole patterning, CNT growth and planarization, and top electrode patterning in a 6-inch wafer. Multiwall carbon nanotubes (MWNTs) are used for interconnection, titanium nitride for the bottom electrode, and aluminum with titanium adhesion layer for the top electrode. We have demonstrated well-defined CNT via series interconnection with 700 nm via diameters within the full wafer. Via resistance of 1.2 kΩ with CNT density of 2.7×10¹⁰/cm²is obtained with small resistance variation within the wafer, which also corresponds to 176 kΩ per one MWNT with 10 nm diameters. The possible approaches for further decrease of electrical resistance will be suggested.