Comparative investigation into surface charged multi-walled carbon nanotubes reinforced Cu nanocomposites for interconnect applications

We present the electrodeposition of copper (Cu) nanocomposites with a high content of carbon nanotubes (CNTs), and evaluate the mechanical and thermal properties of the nanocomposites. Two kinds of multi-walled CNTs (MWCNTs), thermally-annealed at 1200 °C and 2600 °C, are pretreated in a polyelectrolyte solution to show positive charges on their surfaces and added into a sulfuric Cu electroplating solution. The weight fractions of the MWCNTs in the electroplated composites are 5.3 wt% and 2.8 wt%, respectively. The Young's moduli of the composites are approximately 1.2 times and 1.1 times greater than that of a pure Cu thin film, and the coefficients of thermal expansion (CTEs) of the composites are reduced to be 77% and 85% of the CTE of the pure Cu film, respectively. The mechanical strengthening and thermal expansion reduction are found in the composite. These results show that the nanocomposites would be used instead of Cu thin film for interconnect applications.