FinFETs are known to be an evolution of metal-oxide-semiconductor field effect transistors (MOSFETs) comprising a semiconductor channel wrapped vertically by conformal gate electrodes. It was first proposed in the 1990s in order to avoid the short channel effect and other drawbacks resulting from the reduction in the size of transistors. Due to the limitation of nanofabrication, the minimum fin width is around 5nm in current technology.
Over the past decades, microelectronics has developed at a rapid pace following Moore’s Law, with the number of transistors per area increasing every two years. Due to the limitation in precision of nano-fabrication, it is now extremely difficult to further reduce the size of transistors on an integrated circuit. It is therefore very important to seek new candidates for semiconductor materials.
In recent years, new materials such as carbon nanotubes and two-dimensional (2-D) materials have been widely studied for the implementation of nanoscale transistors. In a new study published in Nature Communication, researchers at the Metal Research Institute (IMR) of the Chinese Academy of Sciences and France aimed to replace the conventional Si-based fin with a single 2D atomic layer in the FinFET architecture.
Researchers designed a wet spray chemical vapor deposition (CVD) method to universally grow monolayers of transition metal dichalcogenides (ML-TMDCs, such as MoS2 and WS2) on stepped jigs of the order of 300 nm.
After a dedicated workflow of multistage etching and nanofabrication process, vertical single-layer MoS2 the channels are successfully wrapped with dielectric and gate electrodes, with source and drain electrodes in contact with the 0.6 nm fin channel. The gate electrodes can also be made of a thin film of carbon nanotubes.
The best electrical performance of these ML-FinFETs was obtained to show an on / off ratio of up to 107, an oscillation below the threshold of about 300 mV / dec, and mobility of the order of a few cm2V-1s-1. Simulations have shown that by further optimizing the structure of ML-FinFETs, the lowering of the drain-induced barrier (DIBL) can be lowered to 5 mV / V.
This study resulted in a FinFET with a fin width of less than 1nm via an upward path to grow monolayer MoS (ML)2 (thickness ~ 0.6nm) like the fin, which is almost the physical limit that we can actually reach. Arrays of fins with a minimum pitch of 50 nm are also demonstrated, providing new perspectives for the implementation of nanoelectronics in the foreseeable future where Moore’s Law may no longer be valid.
Mao-Lin Chen et al. A FinFET with an atomic layer channel, Nature Communication (2020). DOI: 10.1038 / s41467-020-15096-0
Quote: Scientists reduce FinFET fin width to almost physical limit (March 10, 2020) retrieved September 24, 2021 from https://phys.org/news/2020-03-scientists-fin-width-finfet- physical-limit. html
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