The light behind the ​ digital age

The process works like a projection system: the photomask defines the circuit pattern, and EUV light at 13.5 nm is reflected onto a photoresist layer on the wafer, transferring the pattern. Rather than magnifying the image, the system scales it down to nanoscale dimensions. This exposure is repeated up to 100 times to create the intricate three-dimensional transistor architectures. The extremely short wavelength enables features on the order of a few nanometers, enabling GPUs with more than 300 billion transistors.

ZEISS provides the high-precision mirror-based optical system at the heart of EUV scanners produced by strategic partner ASML. The system is approximately 1.5 meters high, weighs 3.5 tons, and comprises over 35,000 individual parts. It consists of two functional modules: the illumination system (which uniformly illuminates the mask) and the projection optics (which precisely projects mask structures onto the wafer). After more than 25 years of development, ZEISS has filed more than 1,500 EUV-related patents.

Unlike visible or UV light, extreme ultraviolet light cannot pass through glass or air without being absorbed. This physical constraint required ZEISS to design an entirely mirror-based optical system that operates in a vacuum. The system uses specially coated mirrors with multilayer reflective surfaces to collect, shape, and direct the EUV light from the plasma source via the mask and onto the wafer — representing one of the most significant technical challenges in developing EUV lithography.

In a plasma source developed by ASML, 60,000 tin droplets per second are fired into a high vacuum. Each droplet is hit by two consecutive pulses from a high-power laser from TRUMPF: a pre-pulse causes the droplet to expand, and the main pulse heats it to up to around 220,000°C. This creates a hot plasma that emits EUV radiation at a wavelength of 13.5 nanometers.

The fundamental difference is the wavelength: DUV uses light with wavelengths of 365, 248, or 193 nm, while EUV uses light with a wavelength of 13.5 nm, allowing much finer structures. Additionally, because EUV light is absorbed by all materials including air and glass, EUV systems must operate in a vacuum using only mirrors for the optical path, whereas DUV systems can use glass lenses in a controlled gaseous environment. This makes EUV systems far more complex but enables the shrink required for today's most advanced microchips.​

High-NA stands for High Numerical Aperture. While established EUV lithography uses a numerical aperture of 0.33, High-NA-EUV lithography increases this value to 0.55. This allows the optical system to collect light from a wider angular range and image even finer details. High-NA-EUV lithography enables roughly three times more transistors on the same area and helps extend Moore’s Law beyond 2030. The first microchips produced using High-NA EUV technology have been commercially available since 2026.