Nanosheet oxide semiconductor FETs with ALD InZnO x compared to InGaO x

Abstract We established an atomic layer deposition (ALD) process of InZnO x (IZO) and fabricated ALD IZO FETs for comprehensive characterization, aimed at advancing nanosheet structure and monolithic 3D (M3D) integration technologies. Thermal stability and composition/thickness dependence on device characteristics are systematically explored. Our findings reveal that ALD IZO FETs maintain high thermal stability at temperatures up to 400 °C, and we identify critical trade-offs among key parameters such as mobility, threshold voltage ( V th ), and initial V th shift (Δ V th ) under positive bias stress conditions. ALD IZO FETs show higher mobility, lower V th , and especially smaller initial Δ V th than previously reported in ALD InGaO x (IGO) FETs. These improvements are linked to the intrinsic differences in oxygen dissociation energy between Zn and Ga in the compound of InO x . The material properties and device behavior of IZO FETs obtained in this work will provide insights into their application in M3D integration.