Three-Dimensional “Atomistic” Simulation of Discrete Random Dopant Distribution Effects in Sub-0.1μm MOSFET's

Abstract

In this paper, discrete random dopant distribution effects in sub-0.1μm MOSFET's were studied using three-dimensional, drift-diffusion “atomistic” simulations. Effects due to the random fluctuation of the number of dopants in the MOSFET channel and the microscopicrandom distribution of dopant atoms in the MOSFET channel were investigated. We found that, in addition to the well-known fluctuation of the threshold voltage, there was an average shift of the threshold voltage to a lower value. The average shift was believed to be attributed to the inhomogeneity of channel potential due to the discreteness of channel dopants, and the logarithmic dependence of subthreshold current. Microscopic dopant distribution also gave rise to asymmetry in drain current upon interchanging the source and the drain.