In the ever-evolving world of semiconductors, the quest to pack more performance into ever-smaller chips has driven innovation for decades. With Moore’s Law slowing, the industry has had to reinvent itself—not through smaller transistors alone, but smarter ones. Two transistor architectures stand at the center of this transformation: FinFET and Gate-All-Around (GAA).

Both have changed the game in their time. But as chipmakers race toward 2nm and beyond, GAA is poised to take the crown. So what makes these two transistor designs different, and why does the future seem to favor GAA?

Let’s dive in.

A Quick Primer on Transistors

Before comparing the two, it’s worth remembering what a transistor actually does. It’s essentially an on/off switch for electrical current, forming the building block of all digital circuits. Billions—sometimes trillions—of them are etched onto microchips, making modern computing possible.

As transistors shrink, maintaining control over that current becomes harder. Leakage, power loss, and overheating are just a few of the issues designers battle at nanoscale dimensions. This is where architecture makes all the difference.

EQ.1:Subthreshold Slope (SS) Equation

FinFET: A Revolution in Its Time

Introduced commercially around 2011, FinFET (short for fin field-effect transistor) was the successor to the traditional planar MOSFET. It got its name from the “fin”—a thin, vertical silicon structure through which current flows. The gate (which turns the transistor on or off) wraps around the fin on three sides, improving control over the current.

This three-dimensional structure made FinFETs more efficient at smaller sizes, allowing the industry to scale below the 20nm node while keeping leakage and power consumption in check.

Why FinFET Was a Big Deal:

Better Electrostatics: With gate control on three sides of the channel, FinFETs reduced leakage significantly compared to planar designs.
Power Efficiency: Lower threshold voltages and reduced leakage meant better battery life for mobile devices.
Scalability: It enabled continued node shrinkage for nearly a decade, powering most chips from 16nm down to 5nm.

But like all innovations, FinFET hit its wall.

The FinFET Bottleneck

As engineers approached the 3nm node, FinFETs began to show cracks in the armor:

Short-Channel Effects: With shrinking channel lengths, the gate struggled to control the current flow, leading to increased leakage.
Design Limitations: The fin’s height and width were hard to tune independently, limiting flexibility in power/performance trade-offs.
Thermal Issues: As density increased, heat dissipation became a growing concern.

To go smaller, the transistor needed to evolve again.

Enter Gate-All-Around (GAA)

GAA transistors take the FinFET idea and go one step further: they wrap the gate around all four sides of the channel, offering complete electrostatic control. Instead of a fin, the channel takes the form of one or more nanosheets (or nanowires) stacked horizontally. Each sheet is surrounded by the gate material on every surface.

This design allows for tighter control, reduced leakage, and improved performance—even at dimensions below 3nm.

How GAA Improves Upon FinFET

1. Superior Gate Control

GAA’s full 360-degree gate coverage means the transistor channel is almost perfectly controlled by the gate. This drastically reduces leakage and short-channel effects—two of the biggest problems in advanced nodes.

2. Customizability

In FinFET, tuning performance required major design compromises. GAA allows chip designers to tweak the number of nanosheets or their width for precise control over drive current, power, and area.

Want more performance? Stack more nanosheets. Want less power? Use fewer or thinner sheets.

3. Better Scaling Prospects

GAA’s architecture is inherently more scalable. It’s easier to shrink vertically by stacking more layers than it is to scale out a 3D fin. This makes GAA a natural fit for 2nm and even 1.4nm nodes.

Industry Adoption: Who's Doing What?

Samsung: Leading the GAA Charge

Samsung was the first major foundry to bring GAA to market at the 3nm node in 2022. Their GAA implementation, dubbed Multi-Bridge Channel FET (MBCFET), uses stacked nanosheets and promises 45% area reduction and 50% power savings compared to 7nm FinFETs.

TSMC: Playing It Safe, but Ready

TSMC, the world’s largest chip foundry, has stuck with FinFET through the 3nm node. However, it plans to roll out GAA at 2nm, likely in 2025. TSMC is known for only adopting technologies once they’re fully mature and production-ready.

Intel: RibbonFET and Beyond

Intel’s version of GAA is called RibbonFET, part of its 20A and 18A roadmap. It combines GAA with a novel PowerVia backside power delivery system for improved performance. Intel aims to bring this to market in late 2024 or early 2025.

EQ.2:Drain Current in Saturation for Short-Channel Devices

Challenges with GAA

It’s not all smooth sailing. GAA introduces new manufacturing and design complexities:

Fabrication Difficulty: Producing uniform nanosheets, etching under them without damage, and precisely stacking them is extremely difficult.
Cost: More complex processes and lower yields (initially) drive up manufacturing costs.
EDA Tools and Training: Designers need updated tools and models to work with GAA architectures.

Despite this, the long-term benefits are considered well worth the transition.

What Comes After GAA?

While GAA will likely carry us through several upcoming nodes, it won’t be the end of the line. The semiconductor industry is already exploring:

3D Monolithic Chips: Stacking logic on top of logic, not just memory.
2D Materials: Graphene, molybdenum disulfide (MoS₂), and other atom-thick materials could replace silicon.
Quantum and Neuromorphic Computing: Completely new computing paradigms based on physics and biology.

But for now, GAA is the technology that will keep Moore’s Law on life support.

Conclusion

FinFET changed the game when it arrived, but its time as the king of transistors is ending. Gate-All-Around, with its superior gate control, scalability, and customizability, is emerging as the clear successor for the next era of chipmaking.

While the road to GAA is complex and costly, the benefits in performance, power, and future scaling are undeniable. As we head into the angstrom era of chip design, GAA isn’t just an upgrade—it’s a necessity.

The transistor may be small, but its evolution is shaping the future of everything from smartphones to AI to space travel. And in this next chapter, Gate-All-Around leads the charge.

FinFET vs. Gate-All-Around (GAA): The Future of Transistor Scaling