Investigation of switching and inverter characteristics of Recessed-Source/Drain (Re–S/D) Silicon-on-Insulator (SOI) Feedback Field Effect Transistor (FBFET)

Abstract

In this paper, the switching and inverter characteristics of Recessed-Source/Drain (Re–S/D) Silicon-on-Insulator (SOI) Feedback Field Effect Transistor (FBFET) are presented using a TCAD mixed-mode simulator. FBFETs have recently acquired popularity as alternative steep-switching devices. It has a very steep subthreshold slope (SS) and high ON current (ION). The current in the device is caused by the movement of electrons and holes which creates positive feedback. To improve the device characteristics in SOI FBFET, a Re–S/D technique is incorporated by extending the source and drain regions into the buried oxide (BOX). An improvement in the IONis observed with reduced hysteresis (memory window) in a Re–S/D SOI FBFET compared to conventional SOI FBFETs which is very useful in logic applications. A complementary inverter implemented using n-type and p-type Re–S/D SOI FBFETs is found to have improved voltage transfer characteristics (VTC) and transient response levels than those of SOI FBFET-based inverters. The high logic level is improved to 0.882V from 0.85V and the low logic level is improved to 0.1V from 0.15V in both VTC and transient response of SOI FBFET inverter at a Re–S/D thickness of 50 nm. Hence, a Re–S/D technique is very useful for both improvements in ION and tackling the problem of clear ON/OFF states in FBFET devices. Further, the three-stage Re–S/D SOI FBFET inverter-based ring-oscillator is implemented, and found that the frequency (fo) and propagation delay (tp) are improved with increased Re–S/D thickness.