Transport in ultra-thin-body SOI and silicon nanowire MOSFETs

The ultra-thin-body (UTB) SOI and silicon nanowire MOSFETs are promising devices for future VLSIs because of their high short channel effect immunity. When the thickness of SOI and the width of nanowire are scaled down to the nanometer regime, the transport is strongly affected by the quantum confinement effects. In order to attain high performance nanoscale MOSFETs, the basic understandings of mobility, transport, and band structures of silicon nanostructures are indispensable. A new design methodology of nanoscale devices in which the new physics in nanostructures are positively utilized is strongly required. In UTB MOSFETs, severe mobility degradation has been observed as the SOI thickness (t_SOI) is reduced below 5 nm in both (lOO)-oriented nMOSFET and pMOSFET, which is one of the most crucial issues in future scaled CMOS. In a nanowire MOSFETs, on the other hand, only a few experimental works have been reported previously on the quantum confinement effects. In this study, mobility enhancement in (110)-oriented UTB MOSFETs, instead of (100) MOSFETs, and variability suppression in silicon nanowire MOSFETs are reported.