A Unified Quasi-3D Subthreshold Behavior Model for Multiple-Gate MOSFETs

Based on the quasi-3D potential approach, a unified subthreshold-potential, threshold-voltage, and subthresholdcurrent model is developed for multiple-gate MOSFETs including a quadruple-gate, triple-gate, and omega-gate MOSFET. Thiswork indicates that the scaling-length-oriented subthreshold current rollup Delta I-sub and threshold voltage roll-off Delta V-th provide the physical insight into well-controlled short-channel effects (SCEs) in terms of effective scaling length lambda(eff) according to the scaling factor. Besides the decreased minimum conducting channel potential Phi(C, min), the smaller scaling-length-induced effective channel width/height (W-eff /H-eff) reflects the smaller effective conducting cross-sectional area, which reduces the subthreshold current degradation due to the increased subthreshold resistance R-sub. By accounting for the coupling factor in the quasi-3D potential approach, W-eff, H-eff, and Phi(C, min) will be increased to some extent to decrease R-sub, which, hence, degrades the subthreshold behavior more extensively in response to SCEs.