Random dopant fluctuation variability in scaled InGaAs dual-gate ultra-thin body MOSFETs: source and drain doping effect

In this paper, we present simulation results on statistical variability of threshold voltage and the respective sensitivity to process variations in Dual Gate Ultra-Thin Body (DG-UTB) InGaAs nMOSFETs at two technological nodes (with physical gate length Lg = 15 nm and Lg = 10.4 nm). Particularly, we focus on the effect of Random Dopant Fluctuations (RDF) in both the channel and the source/drain regions. While the effect of other variability sources (i.e., workfunction fluctuation, WFF, and line edge roughness, LER) can be controlled by existing technological strategies, RDF can become significant due to the 'source-starvation' effect. From our analysis, we find in fact that RDF is strongly dependent on source/drain doping, while the effect due to channel doping variation is marginal. Moreover, results indicate the possibility of achieving lower RDF variability effects at very high source/ drain doping levels that are beyond the reach of current process technology. Hence, RDF can potentially become the limiting factor to the overall variability in ultra-scaled InGaAs devices due to the difficulties in achieving very high source/drain doping.