Approximately 13 nm thick HfO2 films are grown on Si wafers by atomic layer deposition under different ozone concentrations at 280 °C using Hf[N(Et)(Me)]4 as Hf precursor.

Variations in the (a) growth rate and (b) film density, measured via the XRR of the HfO2 films with O3 and H2O oxidants as a function of Ts (160–360 °C).

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RuO₂ metal gates were fabricated by a reactive sputtering method under different O₂ gas ratios. For the given sputtering power of 60 W, a ∼13% O₂ ratio was the critical level below or over which RuO₂ film has hyperstoichiometric and stoichiometric compositions, which resulted in a difference in the effective work function by ∼0.2 eV. The stoichiometric RuO₂ film imposes almost no damaging effect to the underlying SiO₂ and HfO₂ gate dielectrics. The RuO₂ gate decreased the equivalent oxide thickness by ∼0.5 nm and leakage current by around two orders of magnitude compared to the Pt-gated samples.

The effect of the carbon concentration on the crystalline phase and dielectric constant (k) of atomic layer deposited HfO 2 films on Ge substrate was investigated. After annealing, the HfO 2 films grown at 200 • C and 280 • C were crystallized to the tetragonal (t) and monoclinic (m) phases, respectively, which was related to the carbon contents within the films and grain boundary energy. To clarify this, the energy difference between a t-and a m-phases ( E tetra ) was calculated by first principles calculations. The higher k value of t-HfO 2 compared to amorphous and monoclinic HfO 2 was experimentally confirmed.