Statistical fluctuation of universal mobility curves in sub‐100 nm MOSFETs due to random oxide interface

We explore the behavior of universal mobility in sub‐100 nm Si MOSFETs, using a novel 3D statistical simulation approach. Our approach is based on 3D Brownian dynamics in devices with realistic Si/SiO 2 interfaces reconstructed from a Gaussian or exponential correlation function. In this approach carrier trajectories in the bulk are treated via 3D Brownian dynamics, while the carrier‐interface roughness scattering is treated using a novel empirical model. Owing to the high efficiency of the transport kernel, effective mobility in 3D MOSFETs with realistic Si/SiO 2 can be simulated in a statistical manner. We first demonstrate a practical calibration procedure for the interface mobility and affirm the universal behaviour in the long channel limit, using single atomic steps and a correlation length of 6 nm. Next, effective mobility in ensembles of MOSFETs with gate length down to 10 nm is investigated. It is found that random‐discrete nature of the Si/SiO 2 interface leads to a distribution of carrier mobility below the interface, which can deviate considerably from universal mobility curves when L gate < 6 Λ , where Λ is the correlation length for the SiO 2 interface. Based on recent data Λ = 2.8 nm, our simulations indicate that universal‐mobility curves should be reliable for MOSFET designs down to a gate length of 17 nm. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)