High-density formation of Ta nanodot induced by remote hydrogen plasma

We have studied the formation of Ta nanodots (NDs) on thermally grown SiO2/Si by exposing a thin metal layer to a remote H2 plasma (H2-RP) without external heating. Atomic force microscopy (AFM) analyses show that a combination of a Ge (∼30.0 nm)/Ta (∼2.0 nm) bilayer stack with subsequent H2-RP exposure is effective for forming electrically isolated Ta NDs with an areal dot density as high as ∼1011 cm−2, where the Ge layer plays an important role as a barrier layer against the oxidation of the ultrathin Ta layer surface. The change in the chemical structure of the Ge/Ta bilayer stack on SiO2/Si upon Ta ND formation by H2-RP exposure is investigated by hard X-ray photoemission spectroscopy (HAXPES) and X-ray photoelectron spectroscopy (XPS).