Copper oxide atomic layer deposition on thermally pretreated multi-walled carbon nanotubes for interconnect applications
Carbon nanotubes (CNTs) are a highly promising material for future interconnects. It is expected that a decoration of the CNTs with Cu particles or also the filling of the interspaces between the CNTs with Cu can enhance the performance of CNT-based interconnects. The current work is therefore considered with thermal atomic layer deposition (ALD) of CuxO from the liquid Cu(I) ?-diketonate precursor [(nBu3P)2Cu(acac)] and wet oxygen at 135C. This paper focuses on different thermal in situ pre-treatments of the CNTs with O2, H2O and wet O2 at temperatures up to 300C prior to the ALD process. Analyses by transmission electron microscopy show that in most cases the CuxO forms particles on the multi-walled CNTs (MWCNTs). This behavior can be explained by the low affinity of Cu to form carbides. Nevertheless, also the formation of areas with rather layer-like growth was observed in case of an oxidation with wet O2 at 300C. This growth mode indicates the partial destruction of the MWCNT surface. However, the damages introduced into the MWCNTs during the pre-treatment are too low to be detected by Raman spectroscopy.
copper copper oxide interconnect carbon nanotubes (cnt) atomic layer deposition (ald) thermal oxidation