  The material and electrical properties of the CNT single vias and array vias
grown by microwave plasma-enhanced chemical vapor deposition were investigated.
The diameters of multiwall carbon nanotubes (MWNTs) grown on the bottom
electrode of Ta decrease with increasing pretreatment power and substrate
temperature while the effects of the growth power and methane flow ratio are
insignificant The decrease of CNT diameters leads to the decrease of the CNT
via diode devices. The increase of growth power enhances the CNT graphitization
degree and thue the conductivity of CNT via diode devices. In the same via
region, the MWNT diode resistances of the array vias are lower than those of
the single vias. The MWNT diode resistances on the bottom electrode of titanium
are lower than those on the bottom electrode of tantalum. It may be attributed
to the smaller tube diameters on the bottom electrode of Ti and the work
function difference between Ta and Ti films with respect to the work function
of CNTs.
