The Efficiency Frontier in EUV Lithography

The path to next-generation lithography depends on scaling extreme ultraviolet (EUV) source power without a proportional increase in energy costs. Researchers from Utsunomiya University, RIKEN, The University of Tokyo, and Tohoku University have demonstrated a 40% boost in extreme ultraviolet conversion efficiency using simultaneous dual-beam 2-µm laser irradiation.

The technical breakthrough involves a 2090-nm, 20-ns Ho:YAG laser targeting a planar Sn target. In single-beam irradiation at 40 mJ, the EUV conversion efficiency (CE) was 2.6%. By splitting that same total energy equally into two beams of 20 mJ each—maintaining identical peak intensity—the researchers raised the EUV CE to 3.6%. This represents the highest reported efficiency for 2-µm-driven laser-produced plasma sources.

This shift in methodology addresses the fundamental tension in chip manufacturing: the need for higher source power at reduced per-pulse energies. The data shows that the EUV source size (60-70 µm) and energetic-ion spectra remained nearly identical across both configurations. This stability confirms that the efficiency gain does not come at the expense of plasma condition quality.

The strategic significance lies in the scalability of the architecture. Because the scheme requires only passive beam splitting, it can scale to three or more beams. This provides a practical route toward multi-kW-class, energy-efficient EUV sources necessary for high-NA and hyper-NA lithography.

For the semiconductor industry, the implication is clear: the bottleneck for advanced nodes is no longer just raw power, but the efficiency of power conversion. As lithography moves toward hyper-NA, the ability to extract more EUV from the same energy footprint will dictate the economic viability of the next generation of transistors.

Watch the development of multi-beam architectures in plasma-driven lithography.