ASML’s high-NA EUV technology is seeping into low-NA tools

ASML has started the installation of the first low-NA EUV tool that’s been fitted with technology originally developed for high-NA systems. Thanks to more powerful ‘high-NA’ wafer stages, along with a more efficient light source, the NXE:3800E is capable of processing over 220 wafers per hour (wph) at a dose of 30 mJ/cm², up from 160 wph at the same dose sported by its predecessor, the NXE:3600D. Additionally, the latest model features a (machine-matched) overlay of 0.9 nm, compared to 1.1 nm for the 3600D.

The stages of high-NA tools had to be seriously beefed up to compensate for the throughput-hurting characteristics of high-NA optics. By definition, a higher NA involves ‘fatter’ light cones, hitting EUV mirrors at a wider range of angles. Unmitigated, this would result in light loss and therefore a hit in throughput, since the reflectance of EUV mirrors is angle-dependent. To avoid losing a significant portion of light, ASML increased the magnification, which shifts the angles of incidence back into optimal territory.