China Dodges 2,000 ASML Patents with New Laser Trick for EUV Lithography

The Technical Trick: Solid-State Laser Against Solid Tin

While ASML uses powerful carbon dioxide lasers fired at moving tin droplets (LPP method), the team at the Shanghai Institute of Optics and Fine Mechanics has opted for a 1-micron solid-state laser impacting a solid tin target. According to an article published in December 2024, this approach promises higher conversion efficiency and a more compact size. The key difference is that the solid-state laser, operating at a shorter wavelength, can generate tin plasma more efficiently, reducing the energy needed and simplifying the optical system. This method, known as solid-target LPP, avoids the complex synchronization of tin droplets required by ASML, potentially lowering maintenance costs and increasing reliability. However, experts point out that conversion efficiency still needs to be demonstrated at industrial scales, and the resulting beam quality may not match that of traditional LPP systems. Lin Nan's team published their results in the journal Chinese Optics Letters, reporting a conversion efficiency of 5%, comparable to ASML's early prototypes in the 2000s.

The Context: The Race for Technological Independence

Since 2019, ASML has been banned from selling its EUV lithography machines to China under US pressure. Each machine costs between $200 and $400 million and is essential for manufacturing chips below 7 nm. China has attempted to develop its own technology but faced a wall of patents. This new method, led by Lin Nan — a former ASML scientist who returned to China in 2021 — bypasses more than 2,000 patents of the Dutch company. Lin Nan, who was a technical lead for light sources in metrology at ASML, joined the Chinese Academy of Sciences as part of a state talent attraction program. His work not only avoids patents but also represents a paradigm shift: instead of copying ASML's design, China has chosen an alternative route that could offer advantages in cost and scalability. According to a report by the South China Morning Post, the Chinese government has invested over $10 billion in lithography research since 2020, and this breakthrough is the first to demonstrate a fully functional EUV light source. However, the light source is only one component of the EUV machine; other critical elements, such as precision optics (multilayer mirrors with atomic roughness), ultra-high vacuum systems, and nanometer wafer stages, remain enormous challenges. China has yet to demonstrate the ability to manufacture mirrors with the required precision (less than 0.1 nm roughness), an area where German companies like Zeiss and ASML itself have decades of advantage.

Implications for the Global Industry

If China manages to scale this technology to mass production, it could reduce its dependence on ASML and alter the geopolitical balance of semiconductors. However, experts note that a long road remains: the light source is only one component of the EUV machine, and other elements like precision optics remain a challenge. Chinese columnist Qiu Yanfang describes the breakthrough as 'genuine engineering,' not just a legal maneuver. In an article for Asia Times, Qiu highlights that Lin Nan's approach not only avoids patents but could also be easier to mass-produce, as solid-state lasers are more common and cheaper than CO2 lasers. Nevertheless, she warns that integrating all subsystems into a complete machine could take years. For ASML, potential Chinese competition could erode its monopoly, though in the short term demand for its machines remains insatiable: in 2024, ASML reported record revenue of €27 billion, with an order backlog extending into 2026. The company is already developing the next generation of EUV machines (High-NA), which will cost over $400 million and enable 2 nm chips. If China achieves a similar breakthrough with its alternative technology, it could force ASML to lower prices or accelerate innovation. For chipmakers like TSMC, Samsung, and Intel, a second source of EUV machines could reduce costs and dependence on a single supplier, increasing the resilience of the global supply chain.

“This patent detour is not just a legal maneuver; it is genuine engineering.” — Qiu Yanfang, Asia Times

Reactions and Perspectives

ASML has not officially commented, but analysts note that the company could face a long-term erosion of its technological advantage. Meanwhile, the US is considering tightening sanctions to prevent China from achieving autonomy in EUV lithography. Specifically, the Biden administration has proposed expanding export restrictions on chip design tools and simulation software, as well as limiting scientific cooperation in key areas. The scientific community is closely following the progress of Lin Nan's team, whose results have been published in peer-reviewed journals. However, some Western experts are skeptical: Dr. Chris Miller, author of Chip War, notes that “China has achieved an important milestone, but replicating the complexity of a complete EUV machine will require at least another decade.” On the other hand, Lin Nan's success could inspire other Chinese scientists to return home, accelerating knowledge transfer. On the commercial front, Chinese companies like SMIC (Semiconductor Manufacturing International Corporation) could be the first beneficiaries, though they currently rely on 193 nm immersion lithography machines for 14 nm chips. If the Chinese EUV light source is integrated into a functional machine, SMIC could leap directly to 7 nm or 5 nm production, challenging TSMC and Samsung in the advanced chip market. However, commercial viability will depend on the ability to produce these machines in volume and at a competitive cost. For now, Lin Nan's breakthrough is a reminder that innovation can arise from necessity, and that the geopolitics of semiconductors is far from settled.