Lithography

Every transistor in an AI accelerator gets its shape from a machine one company builds. ASML sold 327 lithography systems in 2025, 48 of them extreme ultraviolet^[1]. Nobody else makes EUV systems^[2].

How it works

The stencil is a photomask, the film is photoresist and the machine is a scanner (see Photomasks and pellicles).

The wafer is coated with photoresist, a film that changes wherever light touches it. The mask holds one layer of the circuit as a pattern of clear and dark areas, drawn four times larger than life. The machine shines light through the mask, shrinks the image four times with a lens, and lands it on the film. A wash then removes the film where the light hit, and the pattern is left standing on the wafer for the next machine to etch in or fill with metal. Then the film is stripped and the next mask goes in. A chip takes dozens of masks, one per layer.

How lithography prints a chip

1. Coat. The wafer is coated with a thin film that changes wherever light touches it.
2. Stencil. A stencil, called a mask, holds the pattern for one layer of the chip, drawn four times larger than life.
3. Shrink. Light shines through the stencil, and a lens shrinks the image four times and lands it on the film.
4. Wash. A wash removes the film wherever the light landed, and the pattern is left on the wafer.
5. Repeat. The machine steps across the wafer, printing one patch at a time, each about the size of a postage stamp.

Simplified. The newest machines, which use extreme ultraviolet light, carry the image with mirrors in place of a lens.

The image from one mask covers a patch about 26 by 33 mm, so the wafer moves under the lens one patch at a time, close to a hundred patches per wafer. ASML's own throughput rating for an EUV scanner assumes 96 of them^[4]. Before the wafer is exposed, the machine measures alignment marks printed in earlier layers so the new layer lines up with them, and ASML rates the NXE:3400B's matched-machine overlay at 2 nm^[4].

Finer lines need shorter light. The finest light now in use, at 13.5 nm, is stopped by glass and by air, so an EUV scanner works in a vacuum and uses mirrors instead of lenses, and its masks are mirrors too^[5]. The older machines use light more than fourteen times longer^[3]. The immersion type among them gains extra sharpness by filling the gap between lens and wafer with water^[6].

When one exposure cannot draw a pattern finely enough, the layer is printed with two, three or four masks instead. Each extra pass costs a mask, machine time and a chance to misalign, and ASML says one EUV exposure per layer cuts masks and process steps and lowers cost^[2].

Variants and trade-offs

Deep ultraviolet

Deep ultraviolet (DUV) light comes from gas lasers: 248 nanometers from krypton fluoride (KrF), 193 from argon fluoride (ArF), shone through air or water^[3]. These tools still dominate by volume. Of ASML's 327 systems in 2025, 131 were ArF immersion, 78 KrF and 16 ArF dry, all deep ultraviolet, and another 54 were older i-line tools^[7]. The i-line tools use 365 nm light from a mercury lamp, and ASML says they print features as small as 220 nm^[3]. A DUV scanner costs roughly $60 million. DUV is the one tier with named competitors, Nikon and Canon, and ASML still holds above 80 percent of it^[8].

Immersion is the contested tier, because without EUV a fab needs NXT:2000i-class scanners and several passes per layer to reach leading-edge logic, and that is the tier Dutch export licensing covers.

Extreme ultraviolet

The 13.5 nm light comes from shooting molten tin droplets from a generator and hitting each droplet twice, with a low-intensity pulse to flatten it and then a more powerful one that vaporizes it into plasma, a process repeated 50,000 times a second^[3]. Zeiss mirrors carry it to the wafer, and the largest are a meter across, smooth down to tens of picometers, a picometer being a thousandth of a nanometer^[6].

Brighter light means more wafers an hour, and ASML ran the first 1,000-watt EUV source in April 2025^[2]. Its TWINSCAN NXE:3800E now ships at its full 220 wafers an hour, 37 percent better than the NXE:3600D^[2].

High-NA EUV

High numerical aperture (High-NA) raises the aperture from 0.33 to 0.55 and cuts the smallest printable feature from 13 nm to 8 nm^[9]. Its optics shrink the mask image four times in one direction and eight in the other, halving the patch of wafer one exposure covers and doubling the exposures per wafer^[9]. The second-generation TWINSCAN EXE:5200B runs at 175 wafers an hour, 60 percent above the EXE:5000^[2].

Reuters puts a standard EUV tool at around $200 million and a High-NA machine at $350 to $400 million, prices ASML does not publish^[8].

What one lithography system costs. The High-NA figure is quoted as a $350-400M range; the bar shows the low end$M

What one lithography system costs. The High-NA figure is quoted as a $350-400M range; the bar shows the low end

DUV scanner	60 $M
EUV, 0.33 NA	200 $M
High-NA EUV	350 $M

Source: Reuters explainer on ASML's lithography machines, 28 July 2026

Intel and TSMC have chosen differently on High-NA:

• Intel Foundry says it uses High-NA in volume production for select layers of some Intel 18A products^[10]. It installed the first EXE:5200B^[11]. By September 2026 it had run more than one million wafers on High-NA tools, a count that includes tool testing and research as well as volume production^[10].
• TSMC waited, and now says it will use High-NA in high-volume manufacturing from 2030^[12].

ASML recognized four EXE systems in sales in 2025 against two in 2024^[1]. In its 2025 annual report, filed in February 2026, ASML said it expected the platform to start supporting high-volume manufacturing in 2027^[13]. On 8 September 2026 it announced with TSMC a move to 12-inch photomasks to remove stitching constraints, aiming for a pilot mask line by 2031 and 12-inch High-NA systems in production by 2033^[12].

EUV systems ASML recognized in sales each yeartools

EUV systems ASML recognized in sales each year

2023	53 tools
2024	44 tools
2025	48 tools

Source: ASML 2025 annual report (2024 and 2025); 2023 from ASML's Q4 2023 investor presentation

Who makes it

ASML took EUR 32.7 billion in net sales in 2025 at a 52.8 percent gross margin^[1], and in July 2026 raised its 2026 forecast to EUR 43 to 45 billion at 54 to 56 percent^[14]. It assembles more than it makes, listing 5,100 suppliers^[13]. Four of them make the main parts of the EUV machine:

• Zeiss SMT, Oberkochen, makes the illumination system and the six-mirror projection optics^[15].
• Trumpf, Ditzingen, makes the carbon dioxide drive laser, which amplifies a few watts to 40 kilowatts^[16].
• ASML San Diego, which includes the light-source maker Cymer that ASML bought in 2013, designs the source where the laser turns tin into plasma, and builds the droplet generator^[17].
• VDL ETG builds the frames that suspend and position the mirrors^[18].

ASML says the production capacity of Zeiss, its sole supplier of optics, limits how many lithography systems it can build^[13].

Nikon and Canon are specialists now. Nikon sold 22 new chip lithography systems in the year to March 2026, into a market it sizes at 570 units for 2025, and its Precision Equipment business made an operating loss^[19]. Canon's alternative is nanoimprint, where the FPA-1200NZ2C stamps the pattern instead of projecting it, down to a 14 nm linewidth^[20]. Canon delivered one in 2024 to the Texas Institute for Electronics, to be used for research and prototypes^[20].

ASML net system sales by technology, 2025%

EUV48%ArF immersion42%KrF4%Metrology and inspection3%ArF dry2%i-line1%

Source: ASML Q4 2025 investor presentation

Controls and China's answer

Export controls bar EUV from Chinese foundries^[21]. In September 2025, before the Chinese prototype described below was reported, CSIS judged that EUV remained "firmly out of reach" for China despite massive state investment^[21]. Below EUV, the restrictions arrived in this order:

• Dutch national licensing of advanced DUV took effect on 1 September 2023^[22].
• A US rule published on 25 October 2023 put certain immersion scanners bound for advanced chipmaking under US export rules if they held any American content at all, unless the country they were first exported from already controlled them^[23].
• A partial license revocation disclosed on 1 January 2024 stopped NXT:2050i and NXT:2100i shipments to a few Chinese customers^[24].
• The Netherlands widened its licensing from 7 September 2024^[22]. On 15 January 2025 it announced that from 1 April 2025 the license requirement would also cover a very limited number of further goods, among them specific measuring and inspection equipment^[25].
• The BIS Affiliates Rule extended entity-list controls to affiliates owned 50 percent or more by listed entities from 29 September 2025^[26], then BIS suspended it to 9 November 2026^[27].
• The EU added certain Dutch controls to the EU Control List in November 2025, and ASML says this changed nothing for its immersion tools because they already needed a Dutch license^[13].

China fell from 41 percent of ASML's net system sales in 2024 to 33 percent in 2025^[7].

On DUV, Reuters reported in July 2026, on one unnamed source, that Shanghai Aishengna Electronic Technology Group has started producing home-grown immersion DUV tools. The firm was registered in August 2023 with 7 billion yuan of capital and two state shareholders, Shanghai Electric Holding and a Shanghai International Trust subsidiary. It has no website, and has taken in teams from SMEE and the startup Yuliangsheng^[28]. SMEE, the incumbent, is strongest in i-line and even there holds about four percent of the world market^[21].

On EUV there is less evidence, and claims of Huawei mass production in 2026 remain unverified. Reuters reported in December 2025 that a Shenzhen team of former ASML engineers had built a prototype that makes extreme ultraviolet light but no chip^[29]. Between that light and a printed chip sit the mirrors, and ASML's sole supplier of them is Zeiss^[13].

ASML net system sales by the region tools shipped to, 2025%

China33%South Korea25%Taiwan22%United States12%Japan5%Rest of Asia2%EMEA1%

Source: ASML Q4 2025 investor presentation

The chokepoint

If ASML stopped shipping, no fab anywhere could add EUV scanners. Tools already in fabs would keep printing for as long as they were serviced. In its 2025 annual report ASML said about 95 percent of the systems it had sold in the previous 30 years were still in use^[13]. It guarantees service and spare parts for each platform until at least a committed date, subject to export controls^[13]. Even ASML could not rebuild itself quickly, since Zeiss makes its optics and Trumpf its drive laser.

In July 2026 ASML put its 2026 capacity at around 65 standard (low-NA) EUV scanners and said it plans to add 30 percent for 2027^[14].

For AI accelerators, EUV is the point of control. It prints the finest layers, the ones that set how densely transistors and wires pack, and TSMC expects the number of layers needing High-NA to rise as AI designs grow more complex^[12]. Every added layer is more time on a tool nobody else builds.

Key evaluation criteria

• Resolution. Set by the Rayleigh criterion, which puts the smallest printable feature at k1 times the wavelength divided by the numerical aperture^[30]. The factor k1 depends on the chipmaking process and has a physical limit of 0.25^[30]. 13 nm at 0.33 NA, 8 nm at 0.55 NA^[9].
• Throughput. Wafers an hour at a stated dose. 220 on the NXE:3800E, 175 on the EXE:5200B^[2].
• Overlay. How precisely one layer lands on the one below; ASML says the EXE:5200B's improved projection optics, developed with Zeiss, maximize imaging and overlay^[2].
• Field size. The patch of wafer one exposure covers. High-NA halves it^[9]. ASML and TSMC plan 12-inch masks to remove stitching constraints^[12].
• Source power. Brighter light, more wafers an hour, which is why the 1,000-watt demonstration matters^[2].