Paul Scherrer Institute
Villigen, 13.08.2024 – Scientists at PSI have refined the resolution of photolithography. Through their discoveries, they aim to further the miniaturization of computer chips.
The miniaturization of computer chips is a crucial element of the digital revolution, leading to smaller and more powerful computers. This advancement enables technologies such as autonomous driving, artificial intelligence, and the 5G standard in mobile communication. A research group led by Dimitrios Kazazis and Yasin Ekinci from the Laboratory for Nanoscience and X-ray Technology at the Paul Scherrer Institute (PSI) has developed an innovative technique that facilitates the production of even denser circuit designs. Currently, the most advanced microchips feature conductor tracks that are just twelve nanometers apart, approximately 6,000 times thinner than a human hair. The scientists have achieved conductors spaced only 5 nanometers apart, which is 13,000 times thinner than a human hair, allowing circuits to be arranged in a more compact manner than ever before. “Our work showcases the capabilities of structuring with light and demonstrates what can be accomplished with it,” explains Iason Giannopoulos. “This represents a significant advancement for both industry and research.”
Producing chips like we produce images in cinema
Back in 1970, a microchip could hold merely a hundred transistors. Today, a chip no larger than a fingertip can contain around 60 billion elements. These components are created using a method known as photolithography: a thin silicon disk, referred to as a “wafer”, is coated with a photosensitive layer called photoresist. An exposure is then carried out according to the chip’s construction diagram, altering the properties of the photoresist. This change either makes it soluble or insoluble in specific solvents. Subsequent processes then remove either the exposed parts (positive process) or the unexposed parts (negative process), leaving only the desired wiring pattern with conductors on the wafer.
The type of light used is critical for the miniaturization and compaction of chips. According to the laws of physics, shorter wavelengths of light enable denser structures to be replicated. “Deep ultraviolet light” (DUV) has long been employed in the industry, specifically laser light with a wavelength of 193 nanometers. For comparison, the visible spectrum of blue light for humans ends at about 400 nanometers.
Since 2019, manufacturers have started utilizing “extreme ultraviolet light” (EUV) with a wavelength of 13.5 nanometers, representing a reduction by more than a factor of ten. This has allowed even finer structures to be printed, down to 10 nanometers or less. At PSI, researchers utilize synchrotron radiation from the Swiss Light Source (SLS) for their analyses, tailored to the industrial standard of 13.5 nanometers.
Photonic lithography enables the highest resolutions
PSI scientists have advanced conventional EUV lithography by employing indirect irradiation of the sample. In EUV mirror interference lithography (MIL), two coherent beams are reflected by identical mirrors onto the wafer. The rays create an interference pattern dependent on both the angle of the incoming light and its wavelength, allowing the team to achieve resolutions of 5 nanometers between conductors in a single exposure. Under an electron microscope, the conductors displayed good contrasts with sharp edges.
“Our findings indicate that EUV lithography can achieve extremely high resolutions, suggesting that there may be no fundamental limits yet,” states Dimitrios Kazazis. “This is an exciting aspect that expands our understanding of what is possible, opening up new research pathways in vital areas such as EUV lithography and photoresists,” concludes Kazazis.
From the end of 2025: in a new EUVL chamber
At this point, this method is not particularly applicable for industrial chip production due to its slow speed compared to industrial standards and its limitation to producing simple periodic structures rather than complex chip designs. However, it presents a valuable approach for developing photosensitive resins necessary for future chip production, achieving resolutions unattainable in industrial settings. The team intends to continue its research with a new EUV tool at the SLS, expected to be operational by the end of 2025. This new device will be integrated with the SLS 2.0, which is currently being upgraded, offering enhanced performance and capabilities.
Texts: Werner Siefer
About PSI
The Paul Scherrer Institute (PSI) develops, constructs, and operates large, complex research facilities, making them accessible to the national and international scientific community. The institute focuses its research on future technologies, energy and climate, health innovation, and the fundamentals of nature. Training future generations is a central commitment of PSI; hence, about a quarter of its employees are postdoctoral researchers, doctoral candidates, or apprentices. With a total of 2,300 employees, PSI is Switzerland’s largest research institute, operating with an annual budget of around CHF 460 million. PSI is a part of the ETH Domain, which also includes ETH Zurich, EPF Lausanne, Eawag (Swiss Federal Institute of Aquatic Science), Empa (Swiss Federal Laboratories for Materials Science and Technology), and WSL (Swiss Federal Institute for Forest, Snow and Landscape Research).
Original Publication
Extreme ultraviolet lithography reaches 5 nm resolution
I. Giannopoulos, I. Mochi, M. Vockenhuber, Y. Ekinci & D. Kazazis
Nanoscale12.08.2024
DOI: 10.1039/D4NR01332H
Contact Information
Dr. Dimitrios Kazazis
Laboratory of Nanoscience and X-ray Technologies
PSI Center for Photon Science
Paul Scherrer Institute PSI
+41 56 310 55 78
dimitrios.kazazis@psi.ch
[English]
Author
Institut Paul Scherrer
Advancements in Photolithography: Paul Scherrer Institute Reaches New Heights in Microchip Miniaturization
Villigen, 13.08.2024 – Scientists at PSI have perfected the resolution of so-called photolithography. With their findings, they want to contribute to advancing the miniaturization of computer chips.
The miniaturization of computer chips is a key factor in the digital revolution. It enables the creation of smaller, more powerful computers, facilitating advancements in autonomous driving, artificial intelligence, and the 5G standard for mobile telephony. A working group led by Dimitrios Kazazis and Yasin Ekinci at the Laboratory for Nanoscience and X-ray Technology at the Paul Scherrer Institute (PSI) has developed an innovative technique that enables the production of denser circuit designs. Currently, modern microchips have conductor tracks spaced just twelve nanometers apart, which is about 6,000 times thinner than a human hair. However, PSI scientists have purportedly achieved conductor spacing of just 5 nanometers, equivalent to 13,000 times thinner than a human hair. This advancement allows for a more compact arrangement of circuits. “Our work demonstrates the possibilities of structuring with light and proves what can be achieved with light,” explains Iason Giannopoulos. “This represents an important step for both industry and research.”
Revolutionizing Chip Production: Lessons from Cinema
Since the inception of microchips in 1970, their capabilities have expanded enormously. Initially, a microchip could accommodate a mere hundred transistors, while today, chips the size of a fingertip can encompass about 60 billion elements. This is achieved through a technique called photolithography that involves:
- Coating a thin silicon disk, also known as a wafer, with a photosensitive layer called photoresist.
- Exposing the coated wafer to light based on the chip’s construction diagram, resulting in changes to the photoresist properties.
- Removing either the exposed or unexposed parts through various solvents in a process called development.
- Leaving behind only the desired wiring pattern on the wafer.
The Role of Light in Chip Minaturization
The type of light used in photolithography critically influences the miniaturization of chips. Physics dictates that the shorter the wavelength of the light, the denser the structures that can be reproduced. Historically, “Deep Ultraviolet Light” (DUV) with a wavelength of 193 nanometers has been employed in the industry. To offer perspective, the visible blue light spectrum starts around 400 nanometers.
Since 2019, the industry has transitioned to “Extreme Ultraviolet Light” (EUV), which operates at a wavelength of 13.5 nanometers—over ten times shorter than traditional DUV. This shift enables the printing of finer structures, reaching down to 10 nanometers or less. At PSI, scientists are utilizing synchrotron radiation from the Swiss Light Source (SLS) for analyses congruent with the industrial EUV standard of 13.5 nanometers.
Achieving Unprecedented Resolutions with Photonic Lithography
PSI researchers have successfully advanced conventional EUV lithography by employing a technique known as mirror interference lithography (MIL). In this method:
- Indirect irradiation of the sample occurs.
- Two coherent beams are reflected off two identical mirrors onto the wafer.
- The reflected rays forge an interference pattern dependent on both the incident light angle and wavelength.
This novel approach allowed the research group to achieve resolutions of 5 nanometers in a single exposure. Results observed under an electron microscope showed strong contrasts with sharp edges among the conductors. Dimitrios Kazazis remarked, “Our results prove that EUV lithography enables extraordinarily high resolutions, suggesting we still have no fundamental limits.” This opens new avenues for exploration in EUV lithography and photoresists.
Future Prospects: Enhancing Chip Manufacturing with New Technology
While the current methods aren’t immediately applicable to industrial chip production—due to their slow speed and inability to produce intricate chip designs—they present promising avenues for the development of future photosensitive resins. Expectations are set for the end of 2025, when a new EUV tool will be coupled with SLS 2.0, promising enhanced performance and capabilities.
Key Benefits of Innovations in Photolithography
- High Resolution: Achieving resolutions of 5 nanometers paves the way for denser circuit designs.
- Potential for Miniaturization: Smaller component sizes translate to enhanced performance in electronic devices.
- New Research Frontiers: Opens opportunities for future advances in chip design and manufacturing processes.
Table: Comparison of Light Types Used in Photolithography
| Type of Light | Wavelength (nm) | Resolution Potential | Industry Use |
|---|---|---|---|
| Deep Ultraviolet (DUV) | 193 | 12 nm | Current Standard |
| Extreme Ultraviolet (EUV) | 13.5 | 10 nm or less | Adoption since 2019 |
About the Paul Scherrer Institute (PSI)
The Paul Scherrer Institute PSI develops, builds, and operates large research facilities, making them accessible to both national and international scientific communities. PSI’s research focuses on various areas including future technologies, energy and climate initiatives, innovations in health, and fundamental aspects of nature. The institute is committed to training future generations, with about one quarter of its 2,300 employees engaging in postdoctoral research, doctoral studies, or apprenticeships. The annual budget of around CHF 460 million underscores PSI’s stature as Switzerland’s largest research institute. PSI is a constituent of the ETH Domain, which includes ETH Zurich, EPF Lausanne, Eawag, Empa, and WSL.
Contact Information
For inquiries, please reach out to:
Dr. Dimitrios Kazazis
Laboratory of Nanoscience and X-ray Technologies
PSI Center for Photon Science
Paul Scherrer Institute (PSI)
Phone: +41 56 310 55 78
Email: dimitrios.kazazis@psi.ch
References
Publication original:
Extreme ultraviolet lithography reaches 5 nm resolution
I. Giannopoulos, I. Mochi, M. Vockenhuber, Y. Ekinci & D. Kazazis
Nanoscale 12.08.2024
DOI: 10.1039/D4NR01332H
