Integration of GAA Monolayer MoS2 Nanosheet FETs with Gate First Process for Future 2D CFET Scaling

CFETs based on 2D materials hold the potential to replace Si as a channel at advanced technology nodes. In this work, gate-all-around (GAA) nanosheet FETs with the monolayer MoS $\mathbf{M}_{2}$ channels are presented. The MoS $\mathbf{M o n o l a y e r}_{2}$ was successfully suspended above the oxide trench of varying lengths. Less than $\mathbf{2 0 \%}$ sag was observed up to a trench length of 200 nm. For the first time, a gate-first process, in combination with critical point drying, is introduced to scale down GAA nanosheet FETs to 50 nm channel width and length without introducing damage to the monolayer MoS ${ }_{2}$. Perfect conformal gate stack deposition on the monolayer MoS2 sheets is achieved by using TMA ‘soaking’ treatment. The successful demonstration of monolayer GAA 2D nanosheet FET further shows high potential as a basic component for the future 2D CFET chips integration.

I. Introduction

Two-dimensional (2D) semiconductors, such as transition metal dichalcogenide (TMD), have emerged as alluring candidates to further extend Moore’s Law [1], [2]. TMD channels have higher carrier mobility and are more robust to short channel effects at scaled technology nodes than silicon.