Improvement of Amorphous InGaZnO Thin-Film Transistor With Ferroelectric ZrO_x/HfZrO Gate Insulator by 2 Step Sequential Ar/O₂ Treatment

We report the improvement of ferroelectric (FE) amorphous InGaZnO ₄ (a-IGZO) thin film transistors (TFT) by Ar/O ₂ plasma treatment and subsequent thermal annealing. The a-IGZO (In ₂ O ₃ :Ga ₂ O ₃ :ZnO = 1:1:1) and HZO (Hf:Zr = 1:1) layers were deposited by DC sputtering and spray coating, respectively. The Ar/O ₂ plasma exposure for 10s and thermal annealing at 300°C for 15 min on the a-IGZO/HfZrO(HZO) improves the field effect mobility from 18.6 to 20.0 cm ² V ⁻¹ S ⁻¹ , subthreshold swing from 345 to 125 mV/decade, memory window from 0.45 V to 1.0 V, and polarization from $7 ~\mu \text{C}$ /cm ² to $9 ~\mu \text{C}$ /cm ² . The improvement is mainly due to the reduction of oxygen vacancies at the a-IGZO/HZO interface by Ar/O ₂ plasma exposure and subsequent annealing.