China has accumulated 343 immersion DUV lithography machines in a procurement campaign tracked by South Korea's Seoul Economic Daily, with the build-out forming the basis of a 7-nm AI chip production push on the mainland.

The 343-unit count, published by Seoul Economic Daily, marks the largest publicly reported immersion DUV base tied to a single country's advanced-node effort. Immersion DUV systems project 193-nm argon-fluoride light through a layer of purified water, raising the numerical aperture of the projection optics and allowing finer resolution than dry DUV tools.

What is an immersion DUV tool?

Immersion deep-ultraviolet lithography tools sit one step below EUV in resolution but remain the workhorse for advanced logic and memory production.

Specifications at a glance:

• 193-nm ArF excimer laser source
• water-immersion projection optics with NA up to 1.35
• 200–300 wafers per hour throughput at 7-nm multi-patterning
• quadruple-patterning schemes extend resolution to 7-nm-class metal pitches

Dutch supplier ASML holds a monopoly on advanced immersion DUV systems. The TWINSCAN NXT:1980i and NXT:1970i are the high-volume models.

Why target 7 nm through immersion DUV?

The Seoul Economic Daily report ties the procurement to a domestic 7-nm AI chip base. 7 nm is the most advanced logic node currently produced on the Chinese mainland without EUV access. AI accelerators designed at 7 nm deliver transistor densities suited to training and inference workloads, although per-transistor cost and energy efficiency trail 5-nm EUV-based nodes.

Production at 7 nm without EUV requires quadruple patterning in some metal and via layers, multiplying tool time and consumable use compared with EUV-based single-exposure flows.

What does 343 tools deliver in capacity?

A 343-tool fleet can sustain tens of thousands of 7-nm wafer starts per month, with the exact figure driven by:

• share of systems installed versus in storage or transit
• yield and rework rates per layer
• mix of 7-nm variants running on each tool
• multi-patterning layer count

The Seoul Economic Daily report did not break down the fleet by status, foundry owner, or installation date.

How do export controls fit in?

Immersion DUV has been a focal point of coordinated US, Dutch and Japanese export controls since 2023. The Dutch government has restricted ASML from selling EUV tools to China and tightened licensing on certain advanced immersion DUV models. Older-generation tools such as the NXT:1980i remained licensable to Chinese customers through 2024 under updated Dutch rules.

A 343-unit base implies sustained shipments through compliant licensing channels over several years. The figure aligns with the build-up already visible in ASML's quarterly shipment disclosures, which list China as the largest single destination for immersion DUV systems across 2022–2024.

What remains undisclosed

The Seoul Economic Daily report did not publish:

• the accumulation window
• the vendor breakdown
• foundry or IDM ownership of each system
• installed-versus-stored ratio
• derived wafer-output capacity

The 343-tool headline nonetheless gives analysts a quantitative benchmark for tracking the immersion DUV build-out as export-control enforcement evolves and as demand for domestic advanced-node AI silicon continues to rise.