LLNL develops next-generation ultraviolet lithography platform

30 Dec 2024

New research partnership is centered around the Big Aperture Thulium laser.

A research partnership led by Lawrence Livermore National Laboratory (LLNL) has been formed to investigate the next evolution of extreme ultraviolet (EUV) lithography.

The team will participate in the Extreme Lithography & Materials Innovation Center (ELMIC), one of the Microelectronics Science Research Centers being created by the US Department of Energy backed by a total of $179 million in federal funding.

ELMIC aims to advance the basic science driving the integration of new materials and processes into future microelectronic systems, with the LLNL-led project within this center being a four-year, $12 million investigation to expand the fundamental science around EUV generation and plasma-based particle sources.

Other ELMIC projects will focus on key research areas such as plasma-based nanofabrication, 2D-material systems and extreme-scale memory.

The LLNL work will build on the Lab-developed driver system dubbed the Big Aperture Thulium (BAT) laser, a novel petawatt-class laser conceptual design using thulium-doped yttrium lithium fluoride as the laser gain medium. This architecture should deliver ultra-short laser pulses at hundreds of kilowatts of average power.

When initial results from the BAT device were published in 2023, LLNL said that it delivered "over 25 times the highest pulse energies reported by any laser architecture operating near 2-micron wavelength in the world."

Smaller and more powerful chips

The particular central wavelength of thulium-doped yttrium lithium fluoride, lasing at about 2 microns, offers potential advantages over intense lasers that operate at less than 1 micron or at 10 microns. Applications for similar thulium-doped sources, including treatment of kidney stones and welding of plastics, have duly attracted the attention of commercial developers such as Trumpf.

In lithography applications this capability could lead to a next generation "beyond EUV" platforms, producing chips that are smaller, more powerful and faster to manufacture while using less electricity, commented LLNL.

"We have performed the theoretical plasma simulations and proof of concept laser demonstrations over the past five years that lay the foundations for this project," said LLNL laser physicist Brendan Reagan. "Our work has already had quite an impact in the EUV lithography community, so now we’re excited to take this next step."

The researchers plan to pair their compact high-repetition-rate BAT laser with technologies that generate sources of EUV light using ultrashort sub-picosecond and shaped nanosecond pulses, and high-energy X-rays.

"This project will establish the first high-power, high-repetition-rate, about 2-micron laser at LLNL," noted Jackson Williams of LLNL. "The capabilities enabled by the BAT laser also will make a significant impact on the fields of high energy density physics and inertial fusion energy."