Modeling the threshold voltage variation induced by channel random dopant fluctuation in fully depleted silicon-on-insulator MOSFETs

Abstract

In nanoscale fully depleted silicon-on-insulator (FD-SOI) MOSFETs, the standard deviation of threshold voltage (σVth) caused by random dopant fluctuation (RDF) is an important parameter to predict the performance of transistors and circuits. In this paper, an analytic model of σVth considering both the dopant “number” and dopant “position” fluctuation in channels is proposed. A new model of σVth,num caused by “number” is given and the method of obtaining the “position” influence ratio Rp is discussed in this paper. Moreover, the simulation methods are analyzed in detail. The calculated σVth values in FD-SOI MOSFETs are compared with the Sentaurus TCAD simulation results at different channel lengths, channel doping concentrations, SOI film thicknesses, front gate oxide thicknesses, and buried-oxide thicknesses. The comparison shows that the proposed model matches well with the obtained numerical simulation results.