Nanocrystalline ruthenium oxide embedded zirconium-doped hafnium oxide high-k nonvolatile memories

摘要

Metal-oxide-semiconductor capacitors made of the nanocrystalline ruthenium oxide embedded Zr doped HfQ_2 high-k film have been fabricated and investigated for the nonvolatile memory properties.Discrete crystalline ruthenium oxide nanodots were formed within the amorphous high k film after the 950 °C postdeposition annealing step.The capacitor with the Zr-doped HfO_2 high-k gate dielectric layer traps a negligible amount of charges.However,with the nanocrystalline ruthenium oxide dots embedded in the high-k film,the capacitor has a large memory window.The charge trapping capacity and the trapping site were investigated using the constant voltage stress method and the frequency-dependent capacitance-voltage measurement.The memory function is mainly contributed by the hole-trapping mechanism.Although both holes and electrons were deeply trapped to the bulk nanocrystalline RuO site,some holes were loosely trapped at the nanocrystal/high-k interface.The current-voltage and charge retention results confirmed the above-mentioned charge trapping mechanism.In summary,this kind of nanocrystal-embedded high-k dielectric has a long charge retention lifetime,which is suitable for future nanosize nonvolatile memory applications.