Impact of Corner Rounding on Quantum Confinement in GAA Nanosheet FETs for Advanced Technology Nodes

Abstract

Due to the better electrostatic control, semiconductor industry has already adopted gate-all-around FETs (GAAFETs) for upcoming technology nodes. Effects like sub-band quantization, threshold voltage shift, the geometry-dependent density of states (DOS) etc., are predominant in the terminal characteristics of GAAFETs due to strong geometrical confinement, which has a significant impact on both analog and RF characteristics of the device. In this paper, for the first time we demonstrate the impact of corner rounding radius $(r_{c})$ on quantum confinement effects which alter the sub-band quantization levels of the channel. We have used a 2D Schrodinger solver to obtain the sub-band energy levels and used BSIM-CMG framework to predict the effect of sub-band quantization on the terminal characteristics of the device viz. capacitances, drain currents and transconductances with respect to $r_{c}$ variations.