ASML dominates the market for lithography machines used to make chips, but several other companies are looking to reduce that dependence with their own systems.
Almost every field related to high-end processing chips, from CPUs in computers to GPUs for AI training, relies on ASML, based in Eindhoven, the Netherlands. It is the only company that owns the lithography tools needed to manufacture chips using a sub-5nm process.
Each microprocessor has billions of transistors, and nm (nanometer) is a unit of measurement for the size of the transistors. The smaller the size, the more a microprocessor can fit, making it faster and more efficient. For example, TSMC's 5nm chip has about 173 million transistors per square millimeter.
ASML's latest creation is a giant extreme ultraviolet (EUV) lithography machine that weighs 150 tons, is the size of two Airbus A320 passenger jets, and costs $380 million. But it also puts ASML at the center of a global semiconductor war, with the United States trying to block the Dutch company from selling its lithography machines to Chinese manufacturers in a bid to limit further advances.
What else does China have?
For years, China has been restricted from buying EUV machines and has been tapping into imported DUV systems. They combine multiple patterns, dividing them into multiple etching stages to print parts that are half as small. However, this increases complexity and slows down the production process, thereby reducing productivity and raising costs.
China is also building its own lithography tools, pouring billions of dollars into domestic alternatives. SMEE is said to be making progress with a machine capable of producing 28nm chips using DUV technology.
"But developing an EUV system is a completely different challenge," said Jeff Koch, an expert at research firm SemiAnalysis. "In addition to mastering EUV light, China needs to create a supply chain as vast as ASML's, which spans more than 5,000 specialized suppliers."
Some companies are also starting to accelerate their own solutions. Japan's Canon is betting on a Nanoimprint Lithography (NIL) technology that "stamps" circuit patterns directly onto wafers like a printer. NIL can theoretically create chips with nanometer precision but in a more compact, lower-cost machine than ASML's EUV machines.
In terms of the process, NIL creates a master mask layer, onto which the circuit patterns are etched with an electron beam. Droplets of liquid resin are applied to the wafer before the mask layer presses the circuit patterns onto the wafer. Ultraviolet light is used to harden the resin and form the circuit patterns. Finally, the mask layer is removed. These steps are repeated for each chip layer. Canon estimates its method is about 40% cheaper than a comparable system from ASML.
However, to become a mass-market chip-making tool, it must overcome a number of challenges. For example, the liquid resin application process can introduce errors that can damage the wafer. Because chips are built layer by layer, the circuit patterns of each layer must be precisely aligned, otherwise nanoscale errors can “break” the electrical connections. In addition, the number of wafers created per hour is very small, many times lower than ASML’s 180.
NIL is having success outside of semiconductor manufacturing, mainly in smartphone displays and high-precision components. The technology is now penetrating memory chip manufacturing, where defect rates are acceptable compared to logic chips.
“NIL can coexist with EUV lithography, making low-cost manufacturing where possible and moving toward finer details in the future,” said Iwamoto Kazunori, head of Canon’s optical division.
In addition to Canon, Nikon also has some photolithography solutions. In the early 1990s, it was a supplier of lithography equipment to Intel. However, as ASML commercialized its EUV lithography technology, Nikon gradually lost steam. Recently, it is said to be promoting the i-Line, a technology first commercialized in 1990, to design chip processing machines for Chinese companies.
Last August, the Okinawa Institute of Science and Technology (OIST) said it had designed an EUV lithography device that could significantly reduce the cost of manufacturing semiconductors of 7nm and below. The device, developed by Professor Tsumoru Shintake and his colleagues, is simpler in structure and cheaper than ASML's product. If mass-produced, it is expected to reshape the chip manufacturing equipment industry.
Earlier this year, the US invested nearly a billion dollars in the EUV Accelerator center with the goal of developing advanced high-numerical-aperture EUV machines. The center is expected to provide access to standard EUV NA this year and to High-NA EUV in 2026 for members of the US National Semiconductor Technology Center (NTSC) and Natcast.
The power of the ASML system
ASML’s most advanced machine uses high-numerical-aperture (High-NA EUV) technology. It works by firing 50,000 droplets of molten tin into a vacuum chamber. Each droplet is subjected to a double blow: first a weak laser pulse that flattens it into a pancake shape, then a powerful laser that vaporizes it. This turns each droplet into a hot plasma that reaches nearly 220,000 degrees Celsius, about 40 times hotter than the surface of the Sun, and emits extreme ultraviolet (EUV) light.
This light is then reflected by a series of mirrors so smooth that its imperfections are measured in trillionths of a meter. Mirrors focus the light onto a template containing the chip’s circuit blueprint. The beams are then reflected onto a silicon wafer coated with a light-sensitive chemical to print the chip.
ASML’s tools are complex, but the basic principle is very similar to an old slide projector: light passes through a template to project an image onto a surface. A photolithography tool depends primarily on the wavelength of the light. Just as a finer brush allows for finer strokes, a shorter wavelength allows for smaller etchings.
In addition, a microchip, a semiconductor die, is covered with layers of copper wire to carry data and power. An advanced processor can pack more than 100 billion transistors, contain more than 70 layers, and have more than 100 kilometers of wire on a 1.5-liter piece of silicon. compared to a standard postage stamp.
Before EUV, ASML pioneered DUV lithography machines with wavelengths ranging from 248 to 193 nm, creating features as small as 38 nm. However, DUV with wavelengths of 13.5 or as close as 8 nm makes things much more complicated. EUV light is absorbed by air, glass and most materials, so the process must be enclosed in a vacuum, using special mirrors to reflect it. ASML says it has spent two decades perfecting a method of firing a laser into a drop of molten tin to create this “elusive beam.”
Despite having the most advanced technology, ASML is aiming to shrink the wavelength even further to produce lower-process chips. This means the machines must have more mirrors, which add weight and power consumption. In addition, shorter wavelengths also create a new challenge: very high noise, according to expert Yasin Ekinci of the Paul Scherrer Institute, a Swiss semiconductor research center.