The Next Light: Can Particle Accelerators Power the Future of Moore’s Law?

The Need for a Brighter Future in Chipmaking

The engine of the digital age has long been Moore’s Law—the relentless doubling of transistors on a microchip. This progress is a direct result of advances in photolithography, the process of using light to etch circuits onto silicon wafers. To create today’s most advanced chips, the industry relies on Extreme Ultraviolet (EUV) light with a wavelength of 13.5 nanometers.

The current state-of-the-art EUV source technology, while a monumental engineering achievement, is approaching fundamental limits in the power required for the next generation of high-volume manufacturing. This has spurred a search for a new kind of light source, with a promising candidate emerging from the world of high-energy physics: the particle accelerator.

The Incumbent: Laser-Produced Plasma (LPP)

Today’s EUV lithography is enabled by ASML’s Laser-Produced Plasma (LPP) sources. In this system, a high-power CO2 laser pulverizes thousands of molten tin droplets per second, creating an intensely hot plasma that radiates the required EUV light. This technology has successfully brought EUV sources to ~500 W of average power.

However, the industry roadmap calls for source power to scale beyond 1 kW to improve manufacturing throughput and reduce defects. Scaling LPP technology faces significant challenges, primarily related to managing the tin debris generated by the plasma, which can contaminate and damage the priceless collection optics within the system.

The Challenger: Accelerator-Driven Free-Electron Lasers (FELs)

An accelerator-based approach offers a fundamentally different path. In a Free-Electron Laser (FEL), a high-energy beam of electrons is passed through a series of alternating magnets called an undulator. This forces the electrons to “wiggle” and radiate powerful, laser-like light.

An FEL-based source has several key advantages:

• High Power: FELs are scalable to kilowatt-level average power if powered by high rep. rate e- beams.
• Clean Operation: The process occurs in an ultra-high vacuum, producing no debris.
• Tunability: The output wavelength can be adjusted, offering a potential path to “Beyond EUV” lithography at even shorter wavelengths.

The primary drawback of a single-pass FEL is its low intrinsic efficiency, typically converting less than 0.1% of the electron beam’s energy into EUV light. The central challenge, therefore, is to engineer a system that dramatically improves this efficiency and/or increase the rep. rate of the FEL pulses.

Architectures for a High-Efficiency FEL Source

To be commercially viable, an accelerator-based EUV source must be both powerful and efficient. Two main architectures have been proposed in the scientific literature to achieve this. Both place the FEL undulator inside an optical cavity to create a high-gain Regenerative Amplifier FEL (RAFEL), but they differ in how they manage the electron beam.

1. The Energy Recovery Linac (ERL) Approach: An ERL is an exceptionally efficient type of linear accelerator. A high-current, MHz-rate beam of electrons passes through the undulator once to create light. The spent beam is then looped back through the main accelerator out of phase, where it deposits its vast remaining energy back into the accelerating field to power the next bunch. This “energy recovery” process can achieve over 99% efficiency, drastically reducing the system’s power consumption. A recent paper by He et al. (Phys. Rev. Accel. Beams, 2025) details a compact ERL-RAFEL design capable of producing over 2 kW of EUV power.

2. The Storage Ring Approach: This architecture uses a circular accelerator, or storage ring, to act as a repetition rate multiplier. A less demanding, “slow” injector (e.g., kHz) fills the ring with many electron bunches, which then circulate at MHz frequencies. The RAFEL is placed in a straight section of the ring. On every turn, each bunch passes through the RAFEL, amplifying the light stored in the optical cavity. The key challenge is managing the “heat” imparted to the beam by the FEL interaction, which must be balanced by the natural “cooling” effect of synchrotron radiation in the ring’s magnets. This sets a limit on the maximum power that can be extracted.

Outlook

The engineering task of building an accelerator complex with the reliability and uptime required for 24/7 high-volume manufacturing is immense. However, both the ERL and Storage Ring concepts represent sound, intensively discussed physical bases for a next-generation EUV source. They directly address the core challenges of power scaling and efficiency, offering plausible and compelling answers to what might light the way for the future of Moore’s Law.