Reduction of CNT Interconnect Resistance for the Replacement of Cu for Future Technology Nodes

• Published in: IEEE transactions on nanotechnology 2012-01, Vol.11 (1), p.56-62
• Main Authors: Ward, J. W., Nichols, J., Stachowiak, T. B., Quoc Ngo, Egerton, E. J.
• Format: Article
• Language: English
• Subjects: Alignment; Applied sciences; Carbon nanotubes; Copper; Cross-disciplinary physics: materials science; rheology; Delay; Design. Technologies. Operation analysis. Testing; Electrical resistance measurement; Electrical resistivity; Electronics; Exact sciences and technology; Fabrics; Integrated circuit interconnections; Integrated circuits; interconnects; Materials science; Mathematical analysis; Molecular electronics, nanoelectronics; molecular functionalization; Nanoscale materials and structures: fabrication and characterization; Nanotechnology; Nanotubes; Physics; Reduction; Reinforced concrete; Resistance; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; sheet resistance reduction; Studies; Substrates
• ISSN: 1536-125X; 1941-0085
• DOI: 10.1109/TNANO.2011.2148725

Replacement of Cu interconnects with carbon nanotubes (CNTs) has been hindered by the high resistance of the CNTs. In this paper, methods for reducing CNT interconnect sheet resistance are presented. Functionalization with electron accepting molecules decreased sheet resistance up to 60%, giving a minimum sheet resistance of ~55 Ω/sq. Alignment of CNTs within the interconnect further reduced resistance. In contrast to nonaligned fabrics, aligned CNT interconnects maintained a constant resistance as CNT line width decreased, demonstrating a path for scaling to smaller technology nodes. In addition, interconnects made with single-walled CNTs consistently showed lower resistance than those with multiwalled CNTs. Finally, a projected RC delay was calculated that demonstrates improved performance below the 45 nm technology node for CNTs compared to Cu. To achieve the desired RC delay improvement, the aspect ratio of the CNT interconnect should be scaled appropriately and combined with an additional reduction in CNT interconnect sheet resistance to 10 Ω/sq, which is feasible based on the functionalization and alignment methods presented here.