High-Performance Annealing-Free InGaZnOx Thin Film Transistors by Thermal Atomic Layer Deposition

We report indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) fabricated by thermal atomic layer deposition (TALD) within a low thermal budget ({less than or equal to} 300 {degree sign}C) and without post-deposition annealing. A targeted O3 overdose step integrated into the Ga2O3 sub-cycles of the IGZO TALD super-cycle raises the local oxygen chemical potential and helps suppress inter-sub-cycle redox reactions and vacancy formation. Structural and chemical analyses confirm smooth, fully amorphous Al2O3/IGZO stacks with abrupt interfaces and reduced oxygen-vacancy signatures, while cation states remain stable. Standard TFTs fabricated from these layer stacks exhibit excellent device performance, including near-ideal subthreshold swing (SS) values of 66.4-70 mV dec-1, operation windows within 3V, field-effect mobilities ranging between μFE = 23.6-25.6 cm2V-1s−1, threshold voltages (VTH) close to 0 V, and negligible hysteresis. Under positive-bias temperature stress, ΔVTH remains small across 25-85 {degree sign}C indicating good device reliability. A holistic comparison with prior ALD-based oxide TFTs, shows that the combination of low temperature processing, near-ideal SS, and small drift under stress places our devices on the favorable end of performance-stability tradeoff. The O3 overdose concept presented here provides a generalizable lever for oxygen vacancy control in the TALD of multi-cation oxides and is naturally compatible with BEOL and monolithic 3D integration.