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) β-diketonate precursor [(nBu3P)2Cu(acac)] and wet oxygen at 135 °C. This paper focuses on different thermal in situ pre-treatments of the CNTs with O2, H2O and wet O2 at temperatures up to 300 °C 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 300 °C. 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.

Influence of thermal pre-treatments of CNTs onto a subsequent copper oxide ALD process.Figure optionsDownload as PowerPoint slideHighlights
► Study of CuxO atomic layer deposition on thermally pretreated MWCNTs.
► Most pre-treatments resulted in the formation of CuxO particles.
► Areas with layer-like growth occurred after a pre-treatment with wet O2 at 300 °C.
► This growth behavior suggests a partial destruction of the outer CNT shell.
► Damage introduced to the MWCNTs is too low to be detected by Raman spectroscopy.