Low-resistance multi-walled carbon nanotube vias with parallel channel conduction of inner shells [IC interconnect applications]

We have succeeded in lowering the resistance of multi-walled carbon nanotube (MWNT) vias, using parallel channel conduction of each tube´s inner shells. By optimizing the structure of the interface between MWNTs and Ti bottom contact layers, we could obtain a via resistance of 0.7 Ω for a 2-μm-diameter via consisting of about 1000 MWNTs. The corresponding resistance of about 0.7 kΩ per MWNT indicates that most of the inner shells contribute to carrier conduction as an additional channel. The total resistance of the CNT vias that we fabricated is in the same order of magnitude as the theoretical value of W plugs and one order of magnitude higher than the theoretical value of Cu vias.