QUARTZ-TYPE GLASS AND PROCESS FOR ITS PRODUCTION

摘要

To provide quartz-type glass for a microlithographic projection exposure apparatus, which contains at least 51 mass% of SiO<SUB>2</SUB> and which further contains at least one member selected from the group consisting of lanthanum, aluminum, hafnium, nitrogen, scandium, yttrium and zirconium. It is a material which is useful for an illumination system for a microlithographic projection exposure apparatus or as a projection object lens and has a refractive index at 248 nm larger than 1.508 of quartz glass and a refractive index at 193 nm larger than 1.560 of quartz glass and which can be small-sized.