Suppression of Electron Mobility Degradation in (100)-Oriented Double-Gate Ultra-Thin Body nMOSFETs with SOI Thickness of Less Than 2 nm

Much attention has been paid to ultra-thin body (UTB) and double-gate (DG) MOSFETs because of their superior immunity to short channel effect. However, it has been reported that the electron mobility is degraded in DG compared with single-gate (SG) in (100) UTB nMOSFETs with SOI thickness (t_SOI) of around 5-15 nm (Uchida et al., 2003). On the other hand, it has been reported that the hole mobility is enhanced in (100) DG pMOSFETs with t_SOI of around 5-6 nm (Tsutsui et al., 2006). In order to design nano-scale DG CMOSFETs such as FinFETs, it is quite important to understand electron mobility behaviors in DG and to identify the suitable device parameters without mobility degradation. In this study, electron mobility in (100) SG and DG with t_SOI of less than 5 nm is experimentally investigated. It is found for the first time that no mobility degradation in DG compared with SG occurs when t_SOI is 1.7 nm due to strong quantum confinement by ultimately thin SOI.