Higher-Order Effect of Source–Drain Series Resistance on Saturation Drain Current in Sub-20 nm Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

The saturation drain current including a higher-order effect of series resistance is investigated in sub-20 nm metal–oxide–semiconductor field-effect transistors (MOSFETs). The reduction in current by the resistance is calculated using a derived analytical current model. As a result, the reduction rate increases from 15.8 to 24.0% as the gate length decreases from 32 to 18 nm. Ratios of the Nth-order term to the sum of all absolute order terms are calculated. As the gate length decreases, the effect of higher-order terms becomes important for analyzing the effect of the series resistance. Normalized expansion components of the higher-order resistance-effect are compared with the reduction rate to determine the physical reasons for the reduction increase. We find that the ratio of the source resistance to the channel resistance is the dominant factor in device design and development for sub-20 nm MOSFETs.