What Is EUV, and How Does It Work?

Extreme ultraviolet (EUV) light technology is a key driver of change in the semiconductor industry. Lithography, the method used for printing intricate patterns onto semiconductor materials, has advanced by using ever shorter wavelengths since the beginning of the semiconductor age. EUV lithography is the shortest yet.

In development for decades, the first EUV lithography machine bought in batches and ready for production was from ASML, the Dutch semiconductor company.

What Is EUV Lithography?

EUV light refers to the extreme ultraviolet light used for microchip lithography, which involves coating the microchip wafer in a photosensitive material and carefully exposing it to light. This prints a pattern onto the wafer, which is used for further steps in the microchip design process.

The history of computers is the history of the semiconductor industry, which in turn is the history of the relentless pursuit of miniaturization. In the sector’s initial phase from the 1950s to mid-’80s, photolithography was done through UV light and photomasks to project circuit patterns onto silicon wafers.

During this time, Moore’s Law—the 1960s dictum that the number of transistors on a microchip would double every two years—started coming up against the physical limits of this process. This meant that the staggering increases in computing power and reduced technology costs for consumers were also in danger of hitting a limit. From the 1980s to the 2000s, deep ultraviolet (DUV) lithography drove the next generation of miniaturization, using shorter wavelengths in the range of 153 to 248 nanometers, which allowed for smaller imprints on the silicon wafers of semiconductors.

In leading up to the new millennium, researchers and competing firms worldwide looked for breakthroughs in making EUV lithography and its even shorter wavelengths possible. ASML completed a prototype in 2003, though it would take another decade to develop a system ready for production.

Every few years since then, ASML has delivered the next iteration of its EUV lithography systems with more capacity for production and wavelengths down to 13.5 nanometers. This allows for incredibly precise microchip designs and the densest possible placement of transistors on microchips—in short, it enables faster computer speeds.

How EUV Lithography Works

ASML’s EUV lithography systems emit light with wavelengths of about 13.5 nanometers, which is significantly shorter than the wavelengths used in the previous generation of DUV lithography, thus enabling finer patterns to be printed on semiconductor wafers​. The most advanced microchips can have nodes as small as 7, 5, and 3 nanometers, which are made by repeatedly passing the semiconductor wafers through the EUV lithography system.

Though you won’t be able to follow these steps in your garage workshop to make semiconductors, they are important for understanding how the technology involved can be advanced and where potential investment funds might be best placed. First, a high-intensity laser is directed at a material (usually tin) to generate plasma (charged electrons and protons in motion). The plasma then emits the EUV light at a wavelength of about 13.5 nanometers.

The generated light is gathered and directed through a series of mirrors and optics through a mask or reticle as a circuit pattern is placed in the path of the EUV light, in a manner loosely analogous to using a stencil to paint a pattern on a board. A material called photoresist on the wafer is sensitive to EUV light, and the areas exposed to it go through a chemical change and are then etched. New materials may then be deposited in the etched areas to form the various components of the microchip. This process can be repeated up to 100 times with different masks to create multilayered, complex circuits on a single wafer.

After these steps, the wafer undergoes further processes to remove impurities and get the chip ready to be sliced into individual chips. They are then packaged for use in electronic devices.

EUV vs. DUV Lithography

While major purchases of EUV lithography systems have been driving news in the superconductor industry, given the dramatic costs involved and the technological advances it could bring, DUV lithography is still more widely used. It has the advantage of already being in manufacturing facilities with staff trained in its use.

EUV lithography, with its extremely short wavelengths of about 13.5 nanometers, allows for finer etching of smaller features on chips. For its part, DUV lithography operates at wavelengths starting at 153 nanometers. While chipmakers can use this for designs with sizes as small as 5 nanometers or less, pushing the boundaries of physics, DUV light can only be used for sub-10-nanometer sizes with a loss in resolution quality.

EUV lithography systems not only come with the startup costs of newer technologies but also are inherently more expensive than the equipment and maintenance for DUV lithography. For example, EUV lithography systems installed by Intel in 2023 cost $150 million each. This cost makes DUV lithography systems preferred for uses where EUV lithography’s smaller size is unnecessary.

DUV lithography is also a known quantity: There is no need for additional training, new facilities, and other major capital investments that EUV light systems require. DUV light technology is still needed for many chips in phones, computers, cars, and robots, and it has proved robust and versatile. Its relatively simpler processes also mean that DUV lithography can produce more chips per unit of time than EUV lithography, an important point in its favor in light of the global demand for semiconductors.

Many expect DUV lithography to remain popular for years to come. This is in part because of the price of EUV lithography and the technical issues that come with any new technology. In addition, DUV lithograph technology is not stuck in place, continuing to improve how it helps create the chips found in the many electronic devices of our everyday lives.

The industry is likely in a transition, and while EUV light will play an increasingly more central role in chip manufacturing, DUV lithography is still vital to the production of electronics used in our everyday lives.

Advantages and Disadvantages of EUV Lithography

EUV lithography is a relatively new technology that brings many advantages and some drawbacks to consider.

Advantages

EUV lithography brings many advantages that could lead to future developments in microchip production. Here are two of the reasons why semiconductor companies like Intel are investing so much in the technology:

• EUV light can produce more complex and fine patterns on silicon wafers, allowing for more transistors to be placed on a microchip.
• EUV lithography reduces the number of pattern layers (mask count) required to create a circuit.

Disadvantages

EUV lithography has many benefits, but as a new technology, it’s important to consider its drawbacks.

• EUV lithography systems are more expensive than other systems for microchip lithography.
• ASML is the only company manufacturing these systems, which could create a bottleneck for companies wishing to use EUV lithography or in need of support for their machinery.

The Bottom Line

EUV light is used in microchip lithography to produce the patterns necessary to create a microchip, though at far smaller sizes than from previous lithographic techniques. However, because of its novelty, only one company—ASML—makes machines that use it, and they are costly. As the technology matures, it should play a central role in future developments in microchip production.