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

Abstract

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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim {\textbf {24}}\%$ </tex-math></inline-formula> reduction while Tree-FET ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{\textbf {IB}}\,\,=$ </tex-math></inline-formula> 25nm) shows only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim \textbf {20}\%$ </tex-math></inline-formula> reduction in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{\textbf {ON}}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim \textbf {23K}$ </tex-math></inline-formula> in Tree-FET, whereas, in the case of other counterparts, it is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim \textbf {28K}$ </tex-math></inline-formula> . A comparatively smaller variation in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\textbf {T}}$ </tex-math></inline-formula> shift due to the self-heating effect is observed in Tree-FET in order to achieve higher <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{\textbf {ON}}$ </tex-math></inline-formula> , 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(\sim \textbf {3}\%$ </tex-math></inline-formula> ) compared to 5-channel NSFET under a self-heating environment.

Topics & Concepts