Paul Scherrer Institute boosts resolution of EUV lithography to 5nm…

14 Aug 2024

…and Vuzix improves optical waveguide manufacturing.

Researchers at Switzerland’s Paul Scherrer Institute (PSI) have significantly improved the resolution of photolithography. Their aim is to advance the miniaturization of computer chips.

The team, led by Iason Giannopoulos, Yasin Ekinci and Dimitrios Kazazis from the Laboratory of X-ray Nanoscience and Technologies at PSI, has devised a technique for creating even denser circuit patterns.

The work is described in the journal Nanoscale.

Current microchips have conductive tracks that are typically separated by 12 nm. The PSI researchers, by contrast, have managed to produce tracks with a separation of just 5 nm. As a result, circuits can be designed much more compactly than before. “Our work showcases the patterning potential of light. This is a significant step forward for both industry and research,” said Giannopoulos.

In 1970, there was typically only room for around 1000 transistors on a microchip. Today, an area barely larger than the tip of a finger can hold about 60 billion components. These components are manufactured using photolithography, in which a silicon wafer is coated with a light-sensitive layer, the photoresist.

It is then exposed to a pattern of light corresponding to the blueprint for the microchip, which alters the chemical properties of the photoresist. Subsequent treatment removes the exposed or unexposed regions. Conductive tracks are left behind on the wafer forming the desired pattern.

For a long time, the industry used deep ultraviolet light (DUV) with a wavelength of 193 nm. Since 2019, manufacturers have been using “extreme ultraviolet light” (EUV) at 13.5 nm in mass production. This enables the printing of even finer structures, down to 10 nm and less. At PSI, researchers use radiation from PSI’s Swiss Light Source (SLS) for their investigations, tuned to 13.5 nm.

A new EUVL tool in 2025

The PSI researchers extended conventional EUV lithography by exposing the sample indirectly rather than directly. In EUV mirror interference lithography, two mutually coherent beams are reflected onto the wafer by two identical mirrors. The group was able to achieve resolutions, meaning track separations, of just 5 nm in a single exposure.

Viewed under an electron microscope, the conductive tracks were found to have high contrast and sharp edges. Kazazis commented, “Our results show that EUV lithography can produce extremely high resolutions, indicating that there are no fundamental limitations yet. This extends the horizon of what we deem as possible.”

Currently, this approach is not interesting for industrial chip production, because it is very slow compared to industrial standards and can produce only simple and periodic structures rather than a chip design. However, it offers a method for the early development of photoresists needed for future chip production with a resolution that is not possible in the industry.

The team says it plans to continue their research using a new EUV tool at the SLS, expected by the end of 2025. The new tool coupled with the SLS 2.0, which is currently going through an upgrade, will provide much enhanced performance and capabilities.

Vuzix improves optical waveguide manufacturing

Vuzix, a supplier of smart glasses and augmented reality (AR) technologies, has developed a new “micro-touch manufacturing technique” within its optical waveguide fabrication processes, an advance that will allow for better optical performance and higher production yields.

At Vuzix’s waveguide manufacturing facility, in West Henrietta, NY, the production of waveguides is a complex multi-step process performed in class 1000 clean room environments. This uses customized equipment to support the needs of producing in volume the high-quality waveguides required for imaging purposes in smart glasses.

The recent introduction of micro-touch manufacturing techniques during the waveguide imprinting process not only improves yield by reducing the forces that can distort substrates during the imprinting process, but also allows for the introduction of more fragile substrates such as polymers or thinner glass.

Paul Travers, President and CEO, commented, “The high-volume low-cost production of waveguides is one of the major challenges to bringing affordable AR smart glasses with see-through displays to the broader markets. More and more leading firms, such as Garmin and Quanta, see Vuzix as the go-to supplier of this key component. The addition of our innovative process developments will help support production rates in the millions of units annually.”