can someone explain the working /operation of FinFET?

Question

Any resources that give in depth analysis of FinFET working would be helpful. I read a couple of papers on IEEE but most of them had very little information related to the working principle.

Answer 1

This looks like a very good overview - FinFETS: The ultimate guide

They say - and much more:

"The working principle of a FINFET involves the use of a fin-shaped channel instead of a planar channel found in conventional MOSFETs. Unlike planar transistors, which have a flat channel, FinFETs employ a fin-shaped channel that protrudes vertically from the substrate. The channel is surrounded by gate electrodes on three sides, offering superior control over the transistor’s behaviour. The gate structure consists of a gate oxide layer, a gate electrode, and a gate insulator."

&

"Key Advantages of FinFETs

Reduced Leakage Current: One of the primary advantages of FinFETs is their ability to significantly reduce power leakage. The vertical fin structure allows better control of the channel, resulting in reduced leakage current when the transistor is in the off-state. This improved control minimizes energy wastage and enhances power efficiency.

Enhanced Performance: FinFETs offer remarkable performance improvements compared to their predecessors. The three-dimensional structure allows for increased transistor density, enabling more transistors to be packed into a given area. This results in higher processing power and faster switching speeds, leading to improved overall device performance.

Scaling Possibilities: As electronic devices continue to shrink in size, the scalability of transistors becomes crucial. FinFETs have exhibited excellent scaling capabilities, allowing the semiconductor industry to continue its relentless pursuit of miniaturization. The design’s robustness in handling reduced transistor dimensions has been instrumental in maintaining the pace of Moore’s Law.

Lower Power Consumption: FinFETs operate at lower voltages than traditional transistors, leading to reduced power consumption. The improved control over the channel allows for better power management, resulting in longer battery life for portable devices and reduced energy requirements for larger systems.

Better Channel Control: FinFETs allow better control over the channel region, mitigating the short channel effects that plagued MOSFETs. The three-dimensional fin structure and the ability to modulate the width of the fin provides enhanced electrostatic control and reduced undesirable effects, enabling efficient scaling and improved performance. By adjusting the fin width, the threshold voltage and performance of the transistor can be fine-tuned enabling optimization for specific performance requirements."

Image from above linked page

Also worth noting (same source)

Answer 2

In addition to the other answer the Siemens Digital Industries Software Mastering parasitic extraction at the 3 nm process node has the following which has some information about finFET and the later generation GAAFET technology:

Designing integrated circuits (ICs) for the 3 nm process node poses challenges never seen before. One of the biggest challenges for the 3 nm node is the introduction of GAAFETs, including how to model their parasitic capacitance and resistance, given their impact on circuit performance and the significant effect they have on power consumption. Fast, accurate parasitic extraction (PEX) is essential to design success at any node; overcoming design challenges to achieve this goal requires electronic design automation (EDA) PEX tools with advanced extraction capabilities.

What is the 3 nm technology node?

Compared to the 5 nm technology node, the 3nm technology node has the potential to deliver even more improvements in performance, power consumption, and size. This technology introduced gate-all-around (GAA) transistor architecture in place of the finFET transistor architecture used in 5 nm designs. The GAA architecture removes substrate doping and reduces stacking height and source-drain resistance, enabling faster performance with reduced power consumption and smaller size.

Why do we need finFETs and GAAFETs?

FinFET and GAAFET technologies were introduced at advanced nodes to combat unwanted FET physical effects that came with shrinking transistor sizes. Earlier MOSFETs with planar gates didn’t suffer from these effects because they had long channels. As FET gate lengths scaled toward 25 nm, short-channel effects (SCEs) became more and more pronounced, significantly weakening gate control over the channel. With weak channel control, leakage currents become a critical problem that can only be overcome by gaining back the once-strong channel control through new transistor designs.

FinFETs have a double or triple gate structure wrapping around a vertical channel that looks like a fin. FinFETs offer strong channel control at small channel lengths, but they still suffer from SCEs at extreme scaled process features, like gate length or tall fin profiles.

In contrast to finFETs, GAAFET gates fully wrap around the channels (figure 1), allowing for superior control over SCEs. Nanosheet GAAFETs also contain vertically stacked horizontal channels that allow for larger effective channel widths than finFETs without a 2D footprint increase. Designers can use this vertical real estate where needed instead of using x-y space when sizing wider finFET devices. Figure 1. Nanosheet GAAFET with triple stacked nanosheet configuration.

So, from the above finFET was for a 5 nm process, and GAAFETs is for the smaller 3 nm process, supported by the Calibre Design Solutions for IC sign-off verification.

See also What is a FinFET? from the Synopsys design tools. E.g. has pictures of a Planar FET and FinFET:

Definition

A FinFET is a type of field-effect transistor (FET) that has a thin vertical fin instead of being completely planar. The gate is fully “wrapped” around the channel on three sides formed between the source and the drain. The greater surface area created between the gate and channel provides better control of the electric state and reduces leakage compared to planar FETs. Using FinFETs, results in much better electrostatic control of the channel and thus better electrical characteristics than planar FETs.