“Because highly absorbent EUV light weakens by 40% with each reflection, only about 1% of the energy from the light source reaches the wafer when bounced off ten mirrors while more than 10% does when only four mirrors are used.”
OIST’s design cuts the mirror count from ten to four and power use by a factor of ten. So far it exists as a patent application, and the half-scale model comes first. A working system with a corporate partner is penciled in for 2026, and the likeliest partner is Nikon, which quit EUV 15 years ago. ASML’s monopoly is safe until someone builds the thing.