What Is an ASML EUV Lithography Machine and How Does It Work?

Look at the smartphone in your pocket or the laptop on your desk. The incredible processing power packed inside those tiny silicon chips is nothing short of modern magic. But that microchip magic does not happen by accident. Behind every high-performance processor powering modern artificial intelligence, smartphones, and computers lies a machine so complex and precise that only one company on Earth builds it. That company is ASML, based in Veldhoven, Netherlands, and its crowning achievement is the extreme ultraviolet lithography machine.

For decades, the semiconductor industry followed Moore's Law, doubling the number of transistors on a microchip roughly every two years. Eventually, engineers hit a massive physical roadblock. Light has a wavelength, and you cannot use a wavelength of light to print a feature smaller than that wavelength. Traditional visible and ultraviolet light sources simply could not shrink circuits any further. The breakthrough development of extreme ultraviolet technology changed everything, earning ASML's engineering marvel the famous title from MIT Technology Review as "the machine that saved Moore's law."

To understand how these massive systems power the global technology ecosystem, we have to look past the business headlines and dive deep into the fascinating physics, optics, and engineering that make extreme ultraviolet lithography possible.

The Evolution of Lithography: From Visible Light to EUV

Photolithography is the semiconductor manufacturing process of using light to transfer geometric patterns from a photomask onto a light-sensitive chemical coating called photoresist on the surface of a silicon wafer. Think of it like shining a shadow-puppet projector onto a photosensitive wall, but scaled down to microscopic proportions.

In the early days of integrated circuits during the 1960s, manufacturers used visible light wavelengths down to 435 nanometers using a mercury G line. As demand for smaller and faster electronics grew, the industry progressed to ultraviolet light, starting at 365 nanometers, followed by excimer laser wavelengths of 248 nanometers using krypton fluoride, and eventually 193 nanometers using argon fluoride, which became known as deep ultraviolet, or DUV.

1. 1960s

   Visible light wavelengths down to 435 nm used for early chips

2. Ultraviolet

   Shift to UV light starting at 365 nm and 248 nm excimer lasers

3. 193 nm

   Deep ultraviolet (DUV) argon fluoride laser systems dominate production

4. 5 nm

   Extreme ultraviolet (EUV) transition opens the sub-7nm chip era

Shrinking features further required an entirely new paradigm. The concept of extreme ultraviolet was first proposed in the mid-1980s by engineer Hiroo Kinoshita at Nippon Telegraph and Telephone in Japan, who demonstrated the first EUV images in 1986. During the 1990s, US researchers at Lawrence Livermore, Lawrence Berkeley, and Sandia National Laboratories performed critical foundational research funded through a public-private partnership called the EUV LLC. ASML later deployed this intellectual property after decades of research, scaling production from a sluggish prototype in 2006 that produced a single wafer in 23 hours to modern systems capable of producing up to 200 wafers per hour by 2022.

Creating Light from Liquid Tin: The Laser-Produced Plasma Source

The heart of an ASML EUV scanner is its light source. Generating extreme ultraviolet light at a wavelength near 13.5 nanometers is extraordinarily difficult because normal light sources do not emit it efficiently. ASML solved this using a method called laser-produced plasma, or LPP.

Inside a sealed vacuum chamber, a droplet generator ejects molten tin droplets approximately 25 micrometers in diameter at a blistering speed of about 70 meters per second. As these tiny tin droplets fly through the chamber, a high-powered dual-pulse carbon dioxide laser strikes them with pinpoint accuracy.

1. 1
   Droplet Ejection

   Molten tin droplets shoot through a vacuum chamber at 70 meters per second

2. 2
   Laser Strike

   A powerful carbon dioxide laser hits the tin droplets instantly

3. 3
   Plasma Creation

   The laser vaporizes and ionizes the tin into a hot, dense plasma

4. 4
   Light Emission

   The glowing tin plasma radiates the desired 13.5 nm EUV light

The laser vaporizes and ionizes the tin instantly, turning it into a superheated, dense plasma. It is this glowing plasma that emits the desired 13.5-nanometer extreme ultraviolet radiation, providing the intense photon energy needed to print bleeding-edge microchips.

Why Mirrors Must Replace Lenses

If you look inside a traditional microscope or camera, you will see glass lenses bending and focusing light. However, standard refractive lenses made of glass and ordinary air will completely absorb EUV light before it can travel even a few millimeters.

Because EUV light is so easily absorbed by matter, ASML machines must operate entirely inside a high vacuum chamber. More importantly, they cannot use refractive glass lenses at all. Instead, the optical system relies completely on specialized reflective optics—in other words, mirrors.

These are not the mirrors you hang on a bathroom wall. The system uses extreme ultraviolet mirrors manufactured by German optics giant Zeiss, frequently described as the most precise mirrors in the world. Because no single material naturally reflects 13.5-nanometer light effectively, these mirrors are built using alternating microscopic layers of molybdenum and silicon multilayers.

Manufacturing these mirrors requires perfection on an atomic scale. Zeiss perfects them by mapping microscopic imperfections and knocking off individual atomic molecules using advanced techniques like ion beam figuring. If a Zeiss EUV mirror were scaled up to the size of Germany, its highest bump would be less than a millimeter tall.

The Exposure Process: Stenciling Microscopic Circuits

Once the EUV light is generated and guided through the maze of Zeiss mirrors, the actual printing process begins. The focused EUV beam bounces off a reflective photomask, which acts like a microscopic stencil containing the detailed geometric blueprint of a computer circuit.

After reflecting off the photomask, the patterned light beam projects that circuit design directly onto a silicon wafer covered in a light-sensitive chemical coating called photoresist. When the EUV photons strike the photoresist, they trigger a chemical change in the exposed areas. Manufacturers then wash away those exposed sections using specialized solvents, etching the intricate circuitry permanently into the silicon substrate beneath.

DUV

• 193 nanometers
• Refractive glass lenses
• Cleanroom air or water immersion
• 7 nm and older mature nodes

VS

EUV Lithography

• 13.5 nanometers
• Reflective multilayer mirrors
• High vacuum chamber
• Bleeding-edge 5 nm and 3 nm nodes

Real-World Footprint and the Global Tech Supply Chain

ASML does not manufacture consumer microchips itself. Instead, the company sells its massive, highly complex machines to major global semiconductor manufacturers like TSMC in Taiwan, Samsung in South Korea, and Intel in the United States. These foundries rely entirely on ASML's EUV systems to produce cutting-edge smartphone processors, artificial intelligence accelerators, and high-performance server CPUs.

Because these machines are absolute bottlenecks for modern technological advancement, they occupy a unique place in geopolitics. Under pressure from authorities, the Dutch government restricts ASML from shipping its advanced EUV systems to certain regions, prompting intense domestic efforts in countries like China to build independent alternatives. Meanwhile, nations building domestic semiconductor ecosystems—such as India through the India Semiconductor Mission supporting fabs by Tata Electronics and Micron—currently rely on mature and deep ultraviolet nodes like 28 nanometers. While Indian fabrication plants do not house EUV machines yet, Indian engineers, researchers, and global design hubs actively participate in the wider semiconductor design and packaging ecosystem that depends on EUV-produced silicon.

4 Billion EurosASML's record annual turnover fueled by its EUV monopoly

200 Wafers / HourThroughput rate achieved by modern ASML EUV scanners by 2022

23 HoursTime required for ASML's first 2006 EUV prototype to make one wafer

25 MicrometersDiameter of the molten tin droplets shot inside the vacuum chamber

Common Misconceptions About Lithography Machines

People often visualize high-tech manufacturing through science-fiction tropes, leading to several persistent myths about how these systems operate.

Another common misunderstanding involves factory maintenance. You cannot simply open an operating EUV machine like a household appliance or a standard factory tool. Because EUV light is instantly absorbed by air, the entire optical path must remain sealed inside an extreme vacuum, requiring rigorous contamination-control protocols during any service work.

The Bottom Line

The ASML extreme ultraviolet lithography machine represents one of the most astonishing collaborations in human engineering and physics. By mastering the art of vaporizing tin with lasers, harnessing atomic-scale multilayer mirrors, and manipulating light at a 13.5-nanometer wavelength in a vacuum, ASML bridged a physical gap that threatened to halt the digital revolution. Understanding the inner workings of these machines reveals the staggering depth of science required to build the pocket-sized computing power we use every day.