Cubic phase stabilization and improved dielectric properties of atomic-layer-deposited Er_yHf_1-yO_x thin films

The electrical and physical properties of atomic-layer-deposited Er_yHf_1-yO_x thin films have been investigated with different stoichiometries of erbium oxide (Er₂O₃) and hafnium oxide (HfO₂). The as-deposited and annealed Er_yHf_1-yO_x films exhibit much higher dielectric constants than the reported k-values of the corresponding binary oxides. The highest k-value of 37.6 ± 1 is achieved with 13 at.% of erbium in the film. The enhancement in dielectric constant is due to the formation of the cubic HfO₂ phase stabilized by erbium, as revealed by x-ray diffraction experiments. The annealed mixed oxide films exhibit remarkably low oxide charges, low interface states, low leakage, and good breakdown electric fields.