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

Abstract

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.