High Mobility and Robust Top-Gate In₂O₃ Thin Film Transistor by Ozone-Based Treatment

Atomic layer deposition (ALD) In2O3 is a promising candidate channel material for the back-end of line (BEOL) transistors due to its numerous advantages. However, its application is limited by the degenerative doping of the channel caused by the deposition of top-gate (TG) dielectrics. In this study, we utilized mild (the temperature remains < 150 ∘C through gate-stack fabrication steps) ozone-based treatment to improve the interfacial properties of In2O3, resulting in high stability during HfO2 deposition. Our ozone-based In2O3 TG transistors have a high on current (Ion) = 284 μA/μm, a low Subthreshold Swing (SS) = 63 mV/dec at Vd = 1 V for Lch = 1 μm. Additionally, high field-effect mobility (μFE) = 120 cm2V-1s-1, small threshold voltage (VT) shift = -63 mV under positive stress voltage = 2V, and VT shift = -88 mV from 25 ∘C to 125 ∘C are also achieved, demonstrating the great potential of ozone-based treatment for future In2O3 TG transistors.