Comprehensive electrothermal characterization of shrunk nanosheets in gate-all-around field-effect transistors

Abstract

Gate-all-around field effect transistor (GAAFET) possesses a three-dimensional stacked structure, with its channels wrapped by materials of lower thermal conductivity. This configuration hinders heat dissipation, leading to a more pronounced self-heating effect (SHE) compared to FinFETs. The shrinking of channel length, width, and thickness enhances phonon-boundary scattering within the nanosheet, thereby degrading thermal conductivity and exacerbating the SHE. In this paper, the degradation of thermal conductivity and its impact on the electrothermal characteristics of the GAAFET are studied. The calculated results demonstrate that the proposed thermal conductivity degradation model aligns well with the experimental data, whereas the conventional thermal conductivity model underestimates the degradation by up to 50.4 %. Furthermore, using the proposed model, the electrothermal characteristics of GAAFETs in 5 nm node are investigated. It is observed that, compared to the conventional thermal conductivity model employed in TCAD simulator, the peak temperature increases by 4.9 %, while the threshold voltage and the on-state current decrease by 3 % and 1 %, respectively. Consequently, the proposed thermal conductivity model offers a perceptive and accurate analysis of the thermal characteristics of GAAFETs.