Nicole Nagy: The Fabrication of Copper-Carbon Nanotube Composites for Global Interconnects

Nicole Nagy, Katharina Lilienthal, Benjamin Uhlig Interconnects, Center Nanoelectronic Technologies (CNT), Fraunhofer Institute for Photonic Microsystems (Fraunhofer IPMS), Dresden Due to its promising physical and electrical properties Cu-CNT composite could be the future material for metallization in semiconductor technologies. The aim of the work described in this talk is to take a closer look on the integration of Cu-CNTs from lab to fab, along with the consideration of material restrictions in terms of CMOS compatibility. For the formation of the composite by wet methods there are two common ways. The first is conventional Cu plating from acidic baths driven by current (electrochemical deposition, ECD). ECD is carried out either in acidic CuSO4 or organic Cu(CH3COO)2 baths and it needs a conductive layer for charge carrier transport, which limits its application [1]. The second approach is electroless Cu deposition, which is done from basic baths by catalytic reaction (ELD). Often used ELD baths consist of tartrate as chelating agent and formaldehyde (a CMR substance) as reducing agent [2]. The substitution of formaldehyde leads to limited alternatives for chelating agents. Glyoxylic acid in combination with EDTA is well known, less toxic and has additional advantages [3]. Another choice to be made is the catalyst material, which has to face the same material restrictions. In general, there is a strong dependency between the alignment of the CNTs on the substrate and the applicability of these two methods. The effects of various substance combinations, growth properties of CNTs, and other parameters on composite formation performance will be shown. [1] Subramaniam et al. One hundred fold increase in current carrying capacity in a carbon nanotube–copper composite. Nat. Commun. 4:2202 doi: 10.1038/ncomms3202 (2013). [2] Paunovic, M. ELECTROLESS DEPOSITION OF COPPER. In Schlesinger, M. and Paunovic, M. (Ed.) Modern Electroplating. 5th ed. Hoboken: John Wiley & Sons, Inc. 2010, pp. 433-446. [3] Wang et al. Metallization of multi-walled carbon nanotubes with copper by an electroless deposition process. Electrochemistry Communications 6 (2004) pp. 1042–1044. Nicole Nagy is currently working on ECD processes for semiconductor technologies and on metallization of carbon nanotubes within the EU project CONNECT at Fraunhofer IPMS-CNT in Dresden. She received her M.Sc. degree in chemical engineering from University of Applied Sciences Dresden in 2015.