Ruthenium Modified Zr-Doped HfO2 High-k Thin Films with Low Equivalent Oxide Thickness

Thin Zr-doped HfO 2 high-k thin film with an equivalent oxide thickness less than 2 nm has been prepared by including ruthenium into the structure. In addition to forming discrete ruthenium nanoparticles in the amorphous Zr-doped HfO 2 film, the bulk and interfacial properties, e.g., density of oxygen vacancies and layer composition, were changed with the addition of ruthenium. The permittivity of the film was increased due to the dipole enhancement, which was supported from the frequency-dependent capacitance-voltage and the conductance-voltage measurements change. The ruthenium modified ZrHfO film has a leakage current density 5 orders of magnitude lower than that of the thermally grown SiO 2 with the same equivalent oxide thickness. The Schottky emission mechanism was observed in the low electric field regime while the Frenkel-Poole conduction mechanism was applicable in the high electric field regime. A 10-year life expectance is estimated at the gate voltage of 2 V.