The only two places in the world that can build the optical columns inside ASML's lithography scanners -- a key part of semiconductor manufacturing -- are set for dramatic expansion, the manufacturer said on Friday.
Zeiss Semiconductor Manufacturing Technology has confirmed that it's adding around 25,000 square meters of production and production-adjacent space at Oberkochen in southern Germany, with staff moving into the first completed building this month, four years after the 2022 groundbreaking. The remaining buildings will be handed over in stages.
Oberkochen and Wetzlar are the only two places in the world where the optical columns can be built, and ASML's own annual report states that the number of systems it can produce is limited by Zeiss SMT's production capacity. ASML told investors earlier this month that it plans to lift Low-NA EUV output by roughly 30% in 2027.
ASML's 2025 annual report describes Carl Zeiss SMT as its sole supplier of lenses, mirrors, illuminators, collectors, and other critical optical components, held under an exclusive arrangement. If Zeiss couldn't sustain production over a prolonged period, the filing warns, ASML "would effectively cease to be able to conduct our business." Purchases from Zeiss SMT and its subsidiaries reached €4.41 billion in 2025, up from €3.95 billion in 2024 and €3.33 billion in 2023. (1 Euro = 1.14 USD)
CFO Roger Dassen said during ASML's July earnings call that it's close to fully booked on Low-NA EUV for 2027, is raising capacity by about 30% from roughly 65 systems this year, and is evaluating another 30% increase for 2028. He told reporters the same day that the company is compressing its scanner build cycle from around 22 weeks to 15 or 16. It's understood that ASML is planning Low-NA EUV machine price hikes, something which has reportedly upset TSMC.
High-NA projection optics contain more than 40,000 parts and weigh about 12 tons, roughly seven times the volume and weight of standard EUV optics. The illumination system adds another 25,000 parts and 6 tons. Individual High-NA mirrors weigh several hundred kilograms, around twice the size and 10 times the weight of current EUV mirrors, and Zeiss says they're machined for months before reaching the required figure. Verifying them requires a purpose-built vacuum chamber measuring 5 by 10 meters, made up of over 100,000 parts and weighing more than 150 tons. Intel became the first company to ship high-volume logic on 0.55 NA scanners this month. Adding floor space doesn't shorten any of those steps.
ASML held €1.91 billion in loans receivable from Zeiss SMT at the end of 2025, up from €1.44 billion a year earlier, alongside €1.19 billion in advance payments made to secure optical column deliveries. Two €1 billion facilities are in place, signed in September 2021 and September 2024, and ASML issued a further €444 million loan in July 2025 and a €212.5 million short-term loan in November. A May 2025 restatement of the company's framework agreement made the capex loans interest-free, with repayment expected over seven or 15 years and quarterly installments that vary with Zeiss SMT's revenue.
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Zeiss SMT booked €5.055 billion in the fiscal year to September 30, 2025, up 23% and the largest of the Zeiss Group's four segments. It's also building a multifunction factory at Wetzlar, added 300 square meters of cleanroom at Rossdorf last fall, and opened an innovation center in Korea this month.
Luke James is a freelance writer and journalist. Although his background is in legal, he has a personal interest in all things tech, especially hardware and microelectronics, and anything regulatory.
