A ZEISS SMT employee holds the important component, which is crucial for the DUV technology, in shape of a thin siliconplate – the so called wafer – in his hands..

SMT Magazine

DUV Lithography: Light creating digitalization

23 January 2025 6 min read

For more than 50 years, DUV technology has made it possible to combine the increasing demand for high-performance microchips with cost-efficient production – laying the foundation for digitalization. Together with EUV and High-NA-EUV lithography, it sets the pace for a connected, digital future.

Precision in the nanometer range

The bare figures alone are impressive: 80 percent of all microchips manufactured worldwide are produced using the optics of the ZEISS segment Semiconductor Manufacturing Technology (SMT). More than 95 percent of their structures are created with DUV light (deep ultraviolet light) at wavelengths of 193, 248, or 365 nanometers. This enables optical resolutions of less than 40 nanometers on microchips. The most advanced and powerful microchips currently available on the market have up to 100 layers. All microchips contain layers that are created by using DUV light. For some high-end chips, manufacturers also use EUV lithography (extreme ultraviolet light) for additional layers – currently the most advanced technology available for series production.

With extreme ultraviolet light (EUV light) at just 13.5 nanometers, the finest structures in the lowest nanometer range are possible. This enables the semiconductor industry to create ever smaller and more powerful structures on the wafer – a thin, disc-shaped silicon plate that forms the basis for microchips. ZEISS SMT is expected to enable the semiconductor industry to realize the next generation of microchips from 2025 with the further development of High-NA-EUV lithography.

Key technology DUV

Next to EUV and High-NA-EUV lithography, DUV technology is setting the pace for the networked, digital future.

The infographic shows DUV lithography as a key technology that has repeatedly pushed the boundaries of what is technologically feasible over the past 50 years.

Two employees work on a DUV lens from the Starlith® 19xyi series in the clean room at ZEISS Semiconductor Manufacturing Technology.

DUV is firmly established

However, most layers are still produced by chip manufacturers using DUV light. This is also reflected in the continued high demand for DUV optics from ZEISS SMT. The so-called excimer lasers or high-pressure mercury vapor lamps used for DUV light are significantly cheaper to operate than the high-power CO2 lasers used for EUV light. Even though the technology leap from EUV to High-NA-EUV lithography has been in the spotlight in recent months, DUV lithography remains a stable and relevant factor in semiconductor manufacturing.

DUV lithography

A ZEISS SMT employee developing the DUV lenses with 436 nanometers.

Even smaller, even finer

DUV technology has made impressive progress over the past 50 years in order to be able to image ever smaller and more powerful structures on the wafer. Three levers are decisive in continuously pushing the limits of what is possible: the use of ever shorter wavelengths, a higher numerical aperture (NA, opening angle of the lens), and a reduced process factor, which improves the resolution limit of the lens. This is visibly reflected in the size of the DUV lithography optics: the smaller the resolution, the larger the optics.

A DUV product of dry lithography in the clean room of ZEISS SMT.

Evolution of lithography technology

It all began in 1972 with the G-line, which was able to produce structures of 1000 nanometers at a wavelength of 436 nanometers. In 1984, the I-line with a wavelength of 365 nanometers marked the switch to ultraviolet light, which is invisible to humans. With the KrF system in 1990, structures of 80 nanometers were then possible at a light wavelength of 248 nanometers. Six years later, the ArF system followed with 193-nanometer optics, enabling structures of 55 nanometers. Both systems use gas lasers (excimer lasers) as a light source, one with krypton fluoride (KrF) and one with argon fluoride (ArF) for 193 nanometers.

A ZEISS SMT DUV immersion lens in the clean room.

Dry and immersion lithography

ZEISS SMT has been using immersion lithography since 2007. The principle of immersion had already proven itself in microscopy. In this process, an immersion fluid is introduced between the optics and the wafer. The key advantage is that liquids have a higher refractive index than air, which causes the light beam to be deflected more strongly. As a result, the numerical aperture – i.e. the angular range from which an optical system can absorb light – increases, and the resolution improves. With light wavelengths of 193 nanometers, resolutions of less than 40 nanometers are possible.

Dry lithography is the technological predecessor to immersion lithograph – but this does not make it any less relevant. On the contrary: Dry DUV is primarily used in volume manufacturing and is favored for its cost-effective production and low-maintenance machines. The technology is called ‘dry DUV’ because there is air between the last lens and the wafer instead of liquid. Both product lines are firmly established in the ZEISS SMT portfolio and are continuously being developed further with new products.

An employee in the clean room manufactures state-of-the-art DUV components at the ZEISS site in Wetzlar.

More capacity for higher demands

The demand for semiconductors is growing, as demonstrated by the increasing number of smart home appliances, lifestyle products, and the rise of electric mobility. There is space for several thousand microchips in an electric car - most of which are produced using DUV technology. This is why ZEISS SMT is continuously investing in employees, infrastructure and machinery. For example, the production facilities at the Wetzlar site are being expanded with a new multifunctional factory that will employ 150 people and cover a production area of 12,000 square meters. There, state-of-the-art DUV components will be produced in the future.

DUV production in Wetzlar (press release 2024)

With DUV lithography, ZEISS SMT is shaping the future of microchips and providing efficient solutions for a world with a growing need for technology.

Dr. Andreas Knipp Head of Business DUV at ZEISS SMT

DUV – fundamental for digitalization

DUV technology has laid the foundation for ever finer structures. With innovations in optics, mask technology, and process optimization, it has paved the way for ever smaller, more powerful and more energy-efficient microchips. Without DUV, digitalization – today and in the future – would be unthinkable. EUV and High-NA-EUV lithography continue to push the boundaries of what is technologically feasible – and are essential for the production of highly complex, high-performance microchips. DUV lithography is still used for simpler chip structures – for example for touchscreen control in smartphones, memory chips or automotive applications such as navigation systems. And because the demand for these ‘simple’ microchips continues to grow, ZEISS SMT will continue to develop DUV lithography further – side by side with EUV and High-NA-EUV lithography.