Improvement of Amorphous InGaZnO Thin-Film Transistor With Ferroelectric ZrOx/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.