CNT integration on different materials suitable for VLSI interconnects

We have succeeded in direct integration of carbon nanotubes (CNTs) for via interconnects using different back contact materials. Highly doped Si and poly Si are used, aiming at the CNT via interconnects directly from source, drain and gate of transistors. In addition, we propose to use aluminum copper alloy (AlCu) as a metal line because of its higher conductivity compared that of copper in very small geometries. The experimental conditions for CNT growth are optimized on these three substrate materials, which are applied for the direct integration in via holes with success. The achieved density in 1 μm via holes is more than 1012 cm−2, the highest value reported so far.