Equivalent Oxide Thickness (EOT) Scaling With Hafnium Zirconium Oxide High-κ Dielectric Near Morphotropic Phase Boundary

We demonstrate a novel strategy to scaling the equivalent oxide thickness (EOT) of MOSFETs by tuning the composition of Hf _1-x Zr _x O ₂ thin-film near morphotropic phase boundary (MPB) between orthorhombic ferroelectric phase and tetragonal anti-ferroelectric phase. This approach can avoid the shortcomings of mobility and reliability degradation incurred in interlayer (IL) scaling approach and gate leakage increase from band gap reduction in traditional higher κ materials. Through comprehensive theoretical modeling and experimental characterization, we show that: 1) MPB exists in Hf _1-x Zr _x O ₂ system due to phase transformation from orthorhombic phase to tetragonal phase with the increase of Zr concentration, in order to reduce the dipole-dipole interaction energy between the oxygen sub-lattices under compression; 2) κ is maximum (κ=38) near the MPB around 70% Zr as two phases co-exist and even a slight perturbation creates a large charge response; 3) Higher κ in advanced technology node FinFET improves the electrostatics and boosts drive current by 13%, suggesting that this strategy is a promising approach to designing high-κ dielectrics for the next generation CMOS.