Extreme Ultraviolet (EUV) lithography is a revolutionary manufacturing process essential for creating the most advanced semiconductor nodes, utilizing light with an extremely short wavelength of 13.5 nm to pattern minute features onto silicon wafers. At the heart of this system lies the EUV mask blank, which is not a traditional photomask but a highly complex, defect-free substrate. This blank consists of an ultra-smooth, low-thermal-expansion glass mirror coated with precisely forty to fifty alternating layers of molybdenum and silicon, creating a multilayer Bragg reflector that is uniquely capable of efficiently reflecting the otherwise highly absorptive EUV light. The fabrication of this flawless mask blank is a monumental feat of materials science, as even a nanometer-scale defect can ruin the entire mirror and print catastrophic errors onto every chip, making it one of the most critical and challenging components in the entire advanced semiconductor manufacturing ecosystem.
