Investigation of the random dopant fluctuations in 20-nm bulk MOSFETs and silicon-on-insulator FinFETs by ion implantation Monte Carlo simulation

In this paper, we proposed a simulation approach for studying the random dopant fluctuation (RDF) effects in the nanoscale MOSFETs using only the TCAD tools. We use this approach to simulate the RDF effects in the 20-nm gate-length bulk MOSFETs, silicon-on-insulator (SOI) single-gate (SG) and triple-gate (TG) FinFETs for demonstration. This approach utilises the stochastic nature of the Monte Carlo (MC) simulation of ion implantation to capture the RDF phenomena in the devices. The simulation results show that the standard deviation of the threshold voltage ( σV T ) is approximately proportional to the cube root of the channel doping concentration for the simulated conventional bulk MOSFETs. For the SOI SG and TG FinFETs, the σV T increases much less than that of the conventional bulk MOSFETs as the channel doping concentration increases. Besides, the σ V T of the SOI TG FinFETs show about 30–40% reductions comparing to those of the SOI SG FinFETs. The average of the MC simulation results agrees with the implant table simulation results. The reasonable simulation results verify the validity of this TCAD simulation scheme for the RDF study.