PROCESS FOR PRODUCING SILICA GLASS CONTAINING TIO2, AND OPTICAL MATERIAL FOR EUV LITHOGRAPHY EMPLOYING SILICA GLASS CONTAINING TIO2

摘要

Conventional TiO₂-SiO₂ glass contains hydrogen atoms substantially, and during deposition under ultrahigh vacuum condition, the hydrogen molecules will diffuse in the chamber, and H₂ molecules will be taken into a film thereby formed. Hydrogen molecules will readily diffuse, and the optical characteristics of the multilayer film are likely to be thereby changed. In an optical material for EUV lithography, a multilayer film is coated by ion beam sputtering on a silica glass having a TiO₂ concentration of from 3 to 12 mass % and a hydrogen molecule content of less than 5x10¹⁷ molecules/cm³ in the glass.