On the impact of channel compositional variations on total threshold voltage variability in nanoscale InGaAs MOSFETs

Abstract

In this paper we present an analysis of the impact of channel compositional variations on the total threshold voltage variability in nanoscale III-V MOSFETs. The analysis is carried out on a template Dual-Gate Ultra-Thin Body (DG-UTB) MOSFET through TCAD simulations in Sentaurus by Synopsys. The Impedance Field Method (IFM) is employed to evaluate statistical variability for five different sources: Random Dopant Fluctuation (RDF), Work Function Fluctuation (WFF), Body- and Gate-Line Edge Roughness (B-LER and G-LER) and Band Gap Fluctuation (BGF). BGF arises due to the compositional variations of Indium in the compound semiconductor composing the channel, namely InGaAs. Our analysis shows that, by appropriately modeling band gap fluctuations, it is possible to identify a worst-case total relative Vt variability for different amounts of Indium mole fraction variations, providing technologists with an important reference. Side-effects of channel compositional variations on other variability sources are evaluated as well, and are found to have a non-negligible impact on B-LER only.