Investigation of Self-Heating Effect in Tree-FETs by Interbridging Stacked Nanosheets: A Reliability Perspective

This work comprehensively investigates the self-heating effects (SHEs) in Tree-FET at 5nm technological nodes. A comparative analysis of Tree-FET with Nanosheet FET (NSFET) shows that the Tree-FET (3-channel+2-bridge) is more or less comparable to the 5-channel NSFET rather than with 3-channel NSFET. An in-depth physics-based study shows that considering only one aspect of increasing ON current is insufficient to judge Tree-FETs for future technological nodes. Targeting these facts, device reliability is demonstrated through numerical simulations showing that Tree-FET outperforms in a self-heating situation, which is a prime concern at a lower technology node. 5-channel NSFET shows
$\sim {\textbf {24}}\%$
reduction while Tree-FET (
$\text{H}_{\textbf {IB}}\,\,=$
25nm) shows only
$\sim \textbf {20}\%$
reduction in
$I_{\textbf {ON}}$
under self-heating. This is because the bridges create a path to heat removal through electrodes and substrate. The peak temperature difference between channels is
$\sim \textbf {23K}$
in Tree-FET, whereas, in the case of other counterparts, it is
$\sim \textbf {28K}$
. A comparatively smaller variation in the
$\text{V}_{\textbf {T}}$
shift due to the self-heating effect is observed in Tree-FET in order to achieve higher
$I_{\textbf {ON}}$
, showing a promising candidate for circuitry that requires a high drive current. A comparative lower gate capacitance implies that Tree-FET may perform well in digital switching applications. Though Tree-FET is not comparable to NSFET for analog applications due to lesser intrinsic gain, it shows a lesser degradation in cut-off frequency
$(\sim \textbf {3}\%$
) compared to 5-channel NSFET under a self-heating environment.