Physics-based device models for nanoscale double-gate MOSFETs

Abstract

Compact, physics-based models of subthreshold swing and threshold voltage are presented for undoped double-gate (DG) MOSFETs in symmetric, asymmetric, and ground-plane modes of operation. Applying the new device models, a novel scale-length based methodology is demonstrated to comprehensively and exhaustively investigate threshold voltage variations in DG MOSFETs. In light of ultra-thin silicon film used as the channel and possible introduction of high-permittivity gate dielectrics, physical, analytical models of quantum mechanical effects, gate direct tunneling current, and fringe-induced barrier lowering effect are developed to assess their impact on DG MOSFET scalability. Scaling limits projections indicate that individual DG MOSFET's with good turn-off behavior are feasible at 10nm scale; however, practical exploitation of these devices toward gigascale integrated systems requires significant improvement in process control.