Lithography machines have always been a hot topic in the semiconductor field.

Starting from the early deep ultraviolet lithography machines (DUV), their stable and reliable performance laid a solid foundation for the development of the semiconductor industry; then came the extreme ultraviolet lithography machines (EUV) with their unique extreme ultraviolet light source and shorter wavelength, successfully pushing the lithography accuracy to a new height; and now the high numerical aperture (High-NA) lithography machines have officially taken to the historical stage, further enhancing the precision and efficiency of lithography, providing the possibility for manufacturing smaller and more precise chips.

ASML's official website shows that it has assembled two TWINSCAN EXE:5000 high numerical aperture lithography systems. One of them was jointly developed by ASM and imec and will be installed in the joint laboratory of ASML and imec in 2024, with mass production expected in 2025. The other was ordered by Intel in 2018. In December 2023, ASML officially delivered the first batch of modules of the High-NA EUV lithography system, the TWINSCAN EXE:5000, to Intel.

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Unboxing the first High-NA EUV lithography machine

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In January of this year, the main components of ASML's first High-NA EUV lithography machine arrived at Intel. Subsequently, in early March, Intel shared a video showing some of the installation and debugging scenes by the ASML engineering team at Intel's D1X factory in Oregon, USA.

ASML spokesperson Monique Mols said at a media visit event held by the company that the installation of this system, which weighs 150,000 kilograms, took a total of 6 months, requiring 250 containers and 250 engineers. Once assembled, the machine will be as tall as three-story building, which forced Intel to build a new (taller) factory extension to accommodate it. It is estimated that the price of each such High-NA EUV lithography machine may be between 300 million and 400 million US dollars.

It is worth noting that Intel is also the first company in the industry to order the TWINSCAN EXE:5200 lithography machine, with the order placed in January 2022.

According to ASML's roadmap, the first generation of High-NA EUV lithography machine TWINSCAN EXE:5000 may mainly be used by wafer manufacturers for related experiments and testing, so that the company can better understand the use of High-NA EUV equipment and gain valuable experience. Actual mass production will depend on the TWINSCAN EXE:5200 that will be shipped at the end of 2024.Why is a High-NA Lithography System Necessary?

Transition from DUV to EUV

In the era of Deep Ultraviolet (DUV) lithography, scientists have been continuously researching ways to push the limits of DUV technology. To reduce the minimum feature size that can be patterned (referred to as the critical dimension, CD), adjustments can be made to two main parameters: the wavelength of light (λ) and the numerical aperture (NA).

Lithographic resolution (R) is primarily determined by three factors: the wavelength of light (λ), the sine of the maximum angle (θ) that light can pass through the lens (the half-angle of the lens aperture), the refractive index (n), and a coefficient k1. In addition to lithographic resolution, the depth of focus (DOF) is also crucial; a large DOF can increase the clear range of etching, thereby improving the quality of lithography, and the depth of focus can also be improved by increasing the refractive index (n) of the system.

However, there is not much room left in current DUV systems to adjust these parameters.

Entering the EUV era, Extreme Ultraviolet (EUV) lithography can make significant adjustments to the wavelength parameter: it uses 13.5 nm light, while the highest resolution DUV systems use 193 nm light. When the first pre-production EUV lithography platform, NXE, was first shipped in 2010, its CD was reduced from over 30 nm in DUV to 13 nm in EUV.

Moreover, EUV lithography systems not only adjust the wavelength parameter but also possess core technologies such as the light source system, optical lenses, and dual stage systems. The combination of these technologies enables EUV lithography systems to achieve efficient projection lithography and process any pattern without damage.

Transition from EUV to High-NA EUV

ASML's current EUV tools have a numerical aperture of 0.33, which can achieve a resolution of around 13.5 nm. Through a single exposure, they can produce a minimum metal pitch of 26 nm and an approximate interconnect space pitch of 25-30 nm from tip to tip, dimensions sufficient to meet the production requirements of the 4/5 nm node process. Nonetheless, the industry still requires a smaller 21-24 nm pitch for the 3 nm process technology, which is why TSMC's N3B process technology is designed to use standard EUV double patterning technology to achieve smaller pitches, but this method will be quite expensive.After changing the wavelength, to further enhance the resolution of the EUV lithography machine, one must focus on the Numerical Aperture (NA) metric. Let me explain that "NA" refers to the numerical aperture of an optical system, which indicates the angle of incidence of light. Using a lens with a larger NA can print smaller structures. The current EUV lithography machines still use an objective system with NA=0.33. The goal for the next generation is to achieve an optical system with NA=0.5 and above.

Thus, High-NA was born. ASML has already begun delivering the first High-NA EUV system, with the numerical aperture increased from the traditional EUV's 0.33 to 0.55. The resolution has also been improved from 13.5nm to 8nm, enabling the smallest metal pitch of 16nm, which will be very useful for process nodes below 2nm. According to Imec's forecast, even for 1nm node technology, the High-NA EUV system can provide a solution. In addition, in terms of production efficiency, the High-NA EUV system can lithograph over 185 wafers per hour, which is an increase compared to the EUV systems already in mass production. ASML has also set a roadmap to increase the production efficiency of the next-generation High-NA EUV system (EXE:5200) to 220 wafers per hour by 2025.

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What does the High-NA EUV lithography machine mean for Intel?

High-NA EUV is considered a key equipment that can reduce process complexity and manufacturing costs, and it is crucial for manufacturing cutting-edge processes at 2nm and below. High-NA requires not only new optical components but also new light source materials, such as an optical system composed of polished, ultra-smooth curved mirrors manufactured by Zeiss in Germany under vacuum. It may even require new, larger factories to accommodate such machines, all of which will require substantial investment.

Nevertheless, to maintain advantages in performance, power, area, and cost (PPAc) of semiconductors, leading manufacturers such as TSMC, Samsung, Intel, and SK Hynix, the world's top logic and memory chip manufacturers, are already in fierce competition to be the first and to acquire more of ASML's most advanced lithography machines. As early as 2020-2021, ASML indicated that it had received High-NA intent orders from three customers, totaling up to 12 systems.

Intel being the first to obtain this equipment will undoubtedly greatly enhance its chip manufacturing capabilities and efficiency, and help Intel gain a competitive edge in the future advanced process technology race. By using this advanced lithography technology, Intel can produce chips that are 2nm and smaller, faster, thereby gaining a greater competitive advantage in the market. Moreover, as chip processes shrink, Intel can further reduce production costs and enhance product competitiveness.

Furthermore, in terms of high numerical aperture learning, Intel will be ahead of its competitors, which will bring it several advantages. Specifically, since Intel is likely to be the first company to initiate mass production using high numerical aperture tools, the wafer fab tool ecosystem will inevitably follow its requirements. The aforementioned requirements may be translated into industry standards, which could give Intel an advantage over TSMC and Samsung.Intel has completed the development of its Intel 18A (1.8nm) and Intel 20A (2nm) manufacturing processes, with the Intel 20A scheduled to be put into use in the first half of 2024. The well-advanced Intel 18A manufacturing technology is also expected to enter mass production in the second half of 2024. This demonstrates Intel's confidence in the application of High-NA EUV technology and its plan to apply this technology to its main chip production in the coming years. High-NA EUV lithography technology can bring lower production costs and higher product competitiveness to Intel.

In summary, Intel's acquisition of the world's first High-NA EUV lithography machine not only signifies a significant advancement for the company in the field of semiconductor manufacturing but also showcases its determination and capability in promoting the development of advanced lithography technology.

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ASML's High-NA EUV Lithography Machine Production

Currently, ASML has received orders for High-NA EUV lithography machines from companies such as Intel and SK Hynix, with the number ranging between 10 and 20 units. At the same time, ASML plans to produce 20 High-NA EUV lithography machines annually by 2028 to meet market demand.

According to a report from TrendForce, ASML will produce up to 10 next-generation High-NA EUV extreme ultraviolet lithography machines in 2024, with Intel ordering as many as six.

Samsung is also actively seeking to acquire High-NA EUV. In June 2022, Samsung Electronics reached an agreement with ASML on the procurement of high numerical aperture EUV. In February of this year, Samsung Electronics and Dutch equipment giant ASML announced again that they will jointly invest in establishing a semiconductor advanced process R&D center in South Korea and plan to introduce High-NA EUV equipment starting from 2027.

Samsung's cooperation with ASML indicates its ambitions in the semiconductor technology field. By jointly developing and introducing High-NA EUV equipment, Samsung will be able to further enhance its chip manufacturing process and gain a greater competitive advantage in the global semiconductor market. It is worth noting that the introduction and application of High-NA EUV equipment also face challenges, including high equipment prices, yield issues, and technical difficulties in the production process.

Young Seog Kang, a researcher at Samsung responsible for memory production, once stated: The most critical concern for users is the total cost issue. The previous Low-NA has already been put into use, and compared to High-NA EUV, chip manufacturers may prefer to use the more economically feasible Low-NA EUV for double exposure or adopt advanced packaging technology as a supplement. Therefore, High-NA EUV may be more beneficial for logic chip manufacturing, while memory may face cost issues.

In contrast, TSMC is not in a hurry to adopt high numerical aperture EUV in the short term. Wu Sihao, Managing Director of Hua Xin Capital, said that TSMC may need several years to catch up with this trend after 2030.SemiAnalysis and analysts from HuaXing Capital have indicated that TSMC will not immediately follow suit in adopting this technology, primarily due to the cost of using high numerical aperture (NA) EUV, which may be higher than using Low-NA EUV, at least initially, despite the low cost coming at the expense of lower transistor density. TSMC's adoption of EUV technology was a few months later than Samsung's but several years earlier than Intel's.

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Hyper-NA EUV is a significant change for the next decade

Recently, in its 2023 annual report, ASML also disclosed progress on its more advanced Hyper-NA EUV technology for the future.

Martin van den Brink, CTO of ASML, stated in the ASML 2023 Annual Report that Hyper-NA lithography exposure equipment with an NA value above 0.7 is undoubtedly an opportunity for developing chip production technology and is expected to be applied from around 2030. It is anticipated that Hyper-NA lithography exposure equipment will be most relevant to logic chips and will provide a more cost-effective solution than High-NA lithography equipment. For ASML, the key is that Hyper-NA is driving the overall EUV development platform to improve costs and delivery times.

In the future, as process technology continues to advance, when entering the 1nm process node, the metal pitch of transistors will need to become smaller. At that time, wafer manufacturers will require more complex tools than High-NA EUV lithography machines, which is why ASML plans to develop a Hyper NA EUV lithography machine with a higher numerical aperture.

Increasing the numerical aperture of projection optical components is a costly decision, involving significant changes to the design of the lithography exposure equipment. This includes the physical size of the machine, the need to develop many new components, and factors of increased costs. ASML recently revealed that the standard numerical aperture EUV Twinscan NXE is priced at about $183 million, while the High-NA EUV Twinscan EXE is priced at about $380 million or more.

As for the upcoming Hyper-NA lithography exposure equipment, which is expected to be even more expensive, ASML must address two issues: whether the Hyper-NA lithography exposure equipment can be technically feasible and whether it is affordable for leading logic chip manufacturers. Currently, there are only three leading logic chip manufacturers globally, including Intel, Samsung, and TSMC. Japan's Rapidus has not yet developed into a capable competitor. Therefore, while there is a need for Hyper-NA EUV lithography exposure equipment, it must be reasonably priced.

Martin van den Brink has pointed out that the final decision on whether to introduce Hyper-NA lithography exposure equipment will depend on the extent to which ASML can reduce costs. However, after ASML has discussed the necessity and feasibility of Hyper-NA EUV lithography exposure equipment with its customers, the technical conditions for customers to use Hyper-NA EUV lithography exposure equipment for the mass production of logic and memory chips are in place, which is expected to be a significant change in the semiconductor industry over the next decade.