ECS Transactions · 2007 · 13 citations · 0 references
EngineeringMaterials EngineeringMaterials ScienceElectronic MaterialsSemiconductor DevicesSemiconductor MaterialsInterface EngineeringMetal-oxide-semiconductor Field-effect TransistorsOxide SemiconductorsSemiconductor InterfacesSemiconductor SurfacesSilicon MaterialsGate Oxide InterfacesGate OxidesGate Stack EngineeringHigh-k DielectricsInterface DipolesSilicon DioxideSilicon InterfacesSurface Oxidation Mechanisms
Several origins for VFB shift have so far been discussed about metal/high-k/SiO2/Si structures and we focus on three topics such as bottom interface dipole at the high-k/interfacial layer (IL)-SiO2 interface, charge or dipole of bottom reaction layer in IL-SiO2, and dipole due to oxygen vacancy (Vo) in high-k layer by separating each type of these dipoles. We employed bi-layer high-k dielectrics such as HfO2/Al2O3/SiO2 and Al2O3/HfO2/SiO2 and demonstrated that the bottom interface dipole plays a critical role in determining the VFB shifts. We also show that VFB roll-off behavior in thinner EOT region can be associated with charge or dipole of the bottom reaction layer induced by re-oxidation at the IL-SiO2/Si interface. Finally, we show that Vo in HfO2 and Al2O3 dielectrics generated by HfxRu1-x alloy gates induces dipole at the high-k/IL-SiO2 bottom interface.