The United States promotes the development of next-generation EUV lithography technology

LLNL has long been a pioneer in the development of EUV lithography technology.
A laboratory located in California will lay the foundation for the next development of extreme ultraviolet (EUV) lithography technology. The project is led by Lawrence Livermore National Laboratory (LLNL) and aims to promote the next development of EUV lithography technology, centered around the laboratory's developed drive system for large aperture thulium (BAT) lasers.

According to the laboratory, the project led by LLNL will test the ability of BAT lasers to increase EUV light source efficiency by approximately 10 times compared to current industry standard carbon dioxide (CO2) lasers.

LLNL insists that this could lead to the production of the next generation of "Beyond EUV" (BEUV) lithography systems, producing smaller, more powerful, faster to manufacture, and less power consuming chips.

The laboratory conducted a concept validation laser demonstration
LLNL laser physicist Brendan Reagan stated that the laboratory has conducted theoretical plasma simulations and concept validation laser demonstrations over the past five years, laying the foundation for the project. Our work has already had a significant impact on the EUV lithography industry, so now we are delighted to take the next step, "Reagan added.

The laboratory claims that EUV lithography involves high-power lasers that emit tens of thousands of tin droplets per second. The laser heats each droplet with a size of approximately 30 millionths of a meter to 500000 degrees Celsius, generating plasma and producing ultraviolet light with a wavelength of 13.5 nanometers.

Energy efficiency of existing EUV lithography sources
Special multi-layer mirror surfaces guide light through mask plates, which preserve complex patterns of integrated circuits used for semiconductor wafers. According to LLNL's press release, light projects patterns onto the photoresist layer, etching it away to leave the integrated circuit on the chip.

The project also aims to investigate how the energy efficiency of existing EUV lithography sources used in semiconductor production can be improved by utilizing technology developed for a new type of watt level BAT laser. The laser uses thulium doped yttrium lithium fluoride (Tm: YLF) as a gain medium, which can increase the power and intensity of the laser beam.

Scientists plan to conduct a demonstration that will pair a compact high repetition rate BAT laser with technology that uses shaped nanosecond pulses to generate EUV light sources and ultra short sub picosecond pulses to generate high-energy X-rays and particles.
Williams emphasized that the project will establish the first high-power, high repetition rate, approximately 2 microns laser at LLNL.

This progress is expected to benefit the semiconductor industry. Williams emphasized that the functionality of BAT lasers will have a significant impact on fields beyond EUV generation, including high-energy density (HED) physics and inertial fusion energy.

LLNL also insists that the semiconductor industry has been competing to integrate as many integrated circuits and other functions as possible into one chip, making each generation of microprocessors smaller but more powerful. In the past few years, EUV lithography technology has taken the lead as it uses EUV light to etch microcircuits as small as a few nanometers onto advanced chips and processors.

At present, the most advanced EUV lithography technology has been applied to the mass production of chips at 2nm process nodes and is still being continuously optimized. In order to continuously approach the theoretical resolution limit of EUV lithography technology and ensure reliable system performance of lithography machines, further in-depth research is needed on how to effectively manage the thermal effects caused by increasing light source power, while developing EUV photoresist with lower edge roughness and ensuring precise control of feature size and good adhesion. In addition, reducing debris pollution inside the light source to extend the service life of the collection mirror, as well as reducing the probability of pollutants adhering to the mask during exposure, are also important research topics at present.
Along with the mass production of EUV lithography technology, many research and development institutions are also attempting to develop more efficient and relatively low-cost next-generation lithography technologies.

LLNL has long been a pioneer in the development of EUV lithography technology, including early spectroscopic studies that laid the foundation for plasma based EUV sources.

As early as 1988, LLNL proposed the first SXPL system, and researchers further manufactured components and developed techniques for diagnostic validation. In 1989, Kinoshita published a paper proposing the optimal SXPL exposure parameters.

Later in 1994, the National EUV Lithography Program emerged in the United States, led by LLNL SNL、 Composed of researchers from Lawrence Berkeley National Laboratory (LBNL) and AT&T Bell Laboratories, funded by DOE and guided by a technical advisory group consisting of DARPA, DOE, and industry representatives. During this period, research teams in the United States began developing imaging systems and the first precise overlay tool using EUV technology, while related research in Europe and Japan was also actively underway.

Recently, LLNL researchers have developed a new type of "high-order harmonic" light source that can generate more powerful and stable EUV beams. This technology is not only expected to significantly improve the production efficiency of EUV lithography machines, but may also reduce equipment costs. More importantly, it has opened the door for other companies to enter the EUV lithography market.

Source: Yangtze River Delta Laser Alliance