Multilayer facilities required for extreme-ultraviolet lithography

Abstract

We have developed a magnetron sputtering system for the deposition of Mo/Si multilayer (ML) coatings onto large-area, figured optics, as required for the imaging system in a practical, extreme-ultraviolet (EUV) lithography tool. Coating uniformity on figured optics is adjusted by implementing contoured, shaped baffles during ML deposition. We have also developed an EUV reflectometer that is capable of measuring the reflectance versus wavelength across the surface of these optics, so that the coating uniformity can be determined with the required precision. We discuss the ML coating uniformity requirements for a practical EUV lithography tool, describe the facilities and techniques we have developed, and present some recent results wherein these facilities and techniques have been used to deposit high-reflectance coatings onto a variety of spherical and aspherical substrates.