Higher Permittivity Rare Earth-Doped HfO2 and ZrO2 Dielectrics for Logic and Memory Applications

We demonstrate electrical properties of rare earth (RE)-doped HfO₂ and ZrO₂ for application as higher permittivity (k) dielectrics in logic and memory devices. X-ray diffraction (XRD) results show that Dy, Er, and Gd doping stabilizes the higher-k tetragonal phase rather than the lower-k monoclinic phase. This preferred tetragonal phase results in a k~30. Initial electrical results show ~3 nm higher-k enables an equivalent oxide thickness (EOT) of 0.93 nm. Alternatively, ~7nm higher-k reduces leakage currents 1000x relative to HfO₂ achieving <10^-8 A/cm² at an EOT of 2 nm. Capacitance-voltage (C-V) data show increasing amounts of RE dopants shift flatband voltage (Vft) in the negative direction vs. pure HfO₂.