Grant, Nicholas E.

Healy, Brendan F. M.

Khorani, Edris

Leimenstoll, Antonio

Murphy, John D.

Niewelt, Tim

Pain, Sophie L.

Walker, David

Walker, Marc

Yadav, Anup

Hafnium oxide thin films have attracted considerable interest for passivation layers, protective barriers, and anti-reflection coatings. Atomic layer deposition offers a route to produce conformal films at the nanometre scale, but there is a lack of clarity over how the growth conditions affect the film properties. Here we present a study into the role of different co-reactants (O2 plasma, O3 and H2O) for the atomic layer deposition of HfOx on n-type silicon from a tetrakis(dimethylamido)hafnium (TDMAH) precursor at 200 °C followed by post-deposition annealing (up to 500 °C). Through X-ray diffraction and X-ray photoelectron spectroscopy, we demonstrate variations in film composition, stoichiometry and crystallinity with co-reactant. Depth profiling conducted with X-ray photoelectron spectroscopy reveals differences in composition between the HfOx surface and the HfOx/Si interface. We also determine differences in the charge level and chemical passivation through photoconductance decay measurements and Kelvin probe analysis. We find that surface recombination velocities <10 cm s-1 are possible for HfOx films, with the best passivation achieved for H2O-based HfOx (SRVs as low as ~5 cm s-1). We show that with TDMAH as a hafnium precursor, neither co-reactant choice nor annealing ambient influence resulting charge polarity

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Influence of co-reactants on surface passivation by nanoscale hafnium oxide layers grown by atomic layer deposition on silicon

Influence of co-reactants on surface passivation by nanoscale hafnium oxide layers grown by atomic layer deposition on silicon

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