Carbon Nanotube Growth Technologies Using Tantalum Barrier Layer for Future ULSIs with Cu/Low-k Interconnect Processes

We succeeded in developing carbon nanotube (CNT) vias specifically adapted for the copper interconnect process used in ultra large-scale integrated circuits. The CNTs were grown selectively on titanium films using Co catalyst films. The use of tantalum enabled CNTs to be grown on Cu lines and prevented any increase in the sheet resistance of the Cu lines. A Cu wire/CNT via/Cu wire structure was fabricated and low resistance of the via was demonstrated. In addition, tests showed that a high current density of about 10 6 A/cm 2 flowed into the CNT via for 125 hours.