Performance, variability and reliability of silicon tri-gate nanowire MOSFETs

We systematically study short-channel performance, threshold voltage variability, and negative bias temperature instability in silicon tri-gate nanowire transistors (NW Tr.). By introducing epi S/D with thin gate spacer, on-current of NW Tr. is significantly improved for the same off-current thanks to the parasitic resistance (RSD) reduction. <;100>;-oriented NW channel further improves on-current as compared to <;110>; NW channel. In Pelgrom plot of σVth of NW Tr., there exists a universal line whose Avt is smaller than planar Tr. due to gate grain alignment. Deviation of the narrowest Tr. from σVth universal line is eliminated by suppressing RSD. Enhanced degradation by negative bias temperature stress in narrow NW Tr. can be attributed to the electric field concentration at the NW corner.