Bottom up approach yields atomic-thin FinFETs

March 11, 2020 //By Julien Happich
In today’s FinFETs, a semiconducting channel is vertically wrapped by conformal gate electrodes, and the race is on to either shrink the fin’s width or move onto gate-all-around transistors integrating carbon nanotubes as the channel.

Now a team of researchers from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences and CEA Leti in France has found a way to further shrink the fin’s width beyond what’s achievable with traditional top-down fabrication methods. Indeed, in most FinFETs, the fin channel is etched from a bulk plane, with the width inherently limited by the precision of state-of-the-art lithography tools.

The ML-TMD fin as compared to etched Si-fin and nanotubes
in their typical dimensions (top left). Schematic picture of the
ML-FinFET (bottom). The inset shows several options for
depositing the fin materials in this structure.

As described in a Nature Communication paper titled “A FinFET with one atomic layer channel”, the researchers have opted for a bottom-up manufacturing approach to replace the conventional Si-based fin with an atomic-thin monolayer of a MoS2, a 2D-material.

To do so, the researchers designed a wet-sprayed chemical vapor deposition (CVD) method to universally grow monolayers of transition metal dichalcogenides (ML-TMD) such as MoS2 and WS2 on step-shaped templates. Thanks to this bottom-up fabrication approach, the researchers were able to design vertically free-standing 2D MoS2 and WS2 monolayers which they conformally coated with insulating dielectric and metallic gate electrodes, pushing the FinFET to the sub 1nm fin-width limit.

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