Solution-Deposited Carbon Nanotube Flip Chip Interconnect for High-Frequency Applications

A coplanar waveguide (CPW) structure with carbon nanotube bumps as flip chip interconnects is presented. The carbon nanotube (CNT) interconnects are fabricated using a solution-based method. This work shows the feasibility of using solution-deposited CNTs as flip chip interconnects and presents their high frequency characteristics in comparison to similarly-sized gold interconnects. The solution-deposited CNT interconnects have similar resistance to transferred CNT bumps grown by chemical vapor deposition. The fabricated CNT bumps are well shaped and have an average dc resistance of 970 mΩ ( 150 μm in diameter and 10 μm in height). High frequency characterization was carried out up to 40 GHz. The return loss is better than 15 dB and the insertion loss of the CNT interconnect is 0.3 dB higher than conventional gold bump interconnects per transition.