Effect of annealing protection atmosphere on the ferroelectric yttrium doped hafnium oxide thin films

The 10 nm thick yttrium doped hafnium oxide (Y:HfO₂) thin films, prepared by chemical solution deposition which using all-inorganic aqueous salt reagents, were fabricated on Si (100) substrates. The crystalline structure, chemical composition and ferroelectric properties of thin films, annealed in protection atmosphere of Air, Ar and N₂, were examined. Result showed that the crystalline structure and ferroelectric properties of films exhibited a strong annealing protection atmosphere dependence. When compared to annealing protection atmosphere of Air and Ar, the films with the N₂ exhibited lowest m-phase fraction of 19.4%, and the highest oxygen vacancy percentage content of 3.06%, accompanied with the highest relative permittivity of 50.9 and the remanent polarization of 14.6 μC/cm². These excellent ferroelectric properties were correlated with asymmetric orthorhombic phase and the concentration of oxygen vacancy introduced from the nitrogen doping concentration.