Characteristics of Stacked Gate-All-Around Si Nanosheet MOSFETs With Metal Sidewall Source/Drain and Their Impacts on CMOS Circuit Properties

Abstract

In this brief, we computationally examine electrical characteristics of stacked gate-all-around Si nanosheet MOSFETs (GAA NS-FETs) with and without metal sidewall (MSW) source/drain (S/D) by increasing the number of channels (NCs) and their impacts on digital circuits. The ON-current ( I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ) and circuit performances of the NS-FETs without the MSW S/D are limited to three channels due to the electrostatic potential decreasing from the top contacts to the bottom S/D side of NS-FETs; however, the MSW S/D can improve the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> with increasing the NCs over three channels because of low resistivity of tungsten ( 5.6×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> Ω·cm) in the sidewall of S/D and then the circuit performances can be boost by the MSW S/D structure of the stacked GAA NS-FETs over three channels. For example, up to six channels of the NS-FETs with the MSW S/D, the frequency of ring oscillator is 57% increase, compared with the case without MSW S/D. The results of this study can be considered to design the S/D structure of the stacked GAA NS-FETs in emerging device technologies.