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 10–20 at. % stabilizes tetragonal HfO₂ and increases permittivity. The maximum permittivity achieved for HfREO_x is 28. The maximum permittivity for ZrREO is 32. HfGdO metal-insulator-semiconductor capacitors with EOT=1.93 nm and leakage current <1×10^-8 A/cm² after 1070 °C have been demonstrated. [ABSTRACT FROM AUTHOR]