Higher permittivity rare earth doped $HfO2$ for sub-$45-nm$ metal-insulator-semiconductor devices

Rare earth (RE) doping (Gd, Er, Dy) of $HfO2$ reduces leakage current by three orders of magnitude compared with pure $HfO2$⁠. The key to reducing $HfO2$ leakage current and equivalent oxide thickness (EOT) is stabilization of the higher permittivity tetragonal phase. RE doping of $10–20at.%$ stabilizes tetragonal $HfO2$ and increases permittivity. The maximum permittivity achieved for $HfREOx$ is 28. The maximum permittivity for ZrREO is 32. HfGdO metal-insulator-semiconductor capacitors with $EOT=1.93nm$ and leakage current $<1×10−8A∕cm2$ after $1070°C$ have been demonstrated.