An Analytical Threshold Voltage Model of Fully Depleted (FD) Recessed-Source/Drain (Re-S/D) SOI MOSFETs with Back-Gate Control

Abstract

This paper presents an analytical threshold voltage model for back-gated fully depleted (FD), recessed-source drain silicon-on-insulator metal-oxide-semiconductor field-effect transistors (MOSFETs). Analytical surface potential models have been developed at front and back surfaces of the channel by solving the two-dimensional (2-D) Poisson’s equation in the channel region with appropriate boundary conditions assuming a parabolic potential profile in the transverse direction of the channel. The strong inversion criterion is applied to the front surface potential as well as on the back one in order to find two separate threshold voltages for front and back channels of the device, respectively. The device threshold voltage has been assumed to be associated with the surface that offers a lower threshold voltage. The developed model was analyzed extensively for a variety of device geometry parameters like the oxide and silicon channel thicknesses, the thickness of the source/drain extension in the buried oxide, and the applied bias voltages with back-gate control. The proposed model has been validated by comparing the analytical results with numerical simulation data obtained from ATLAS™, a 2-D device simulator from SILVACO.