Melted synthetic quartz, process for its manufacture and optical element for excimer lasers

摘要

Disclosed is a method for producing a synthetic fused silica member comprising vaporizing a raw material silane compound, hydrolyzing or oxidizing by combustion the vaporized silane compound in oxyhydrogen flame to form silica microparticles so that the silica microparticles deposit on a rotating refractory carrier, and melting the silica microparticles during the deposition to form the synthetic fused silica member, characterized in that sulfur impurities are preliminarily removed from the raw material. Also provided is a synthetic fused silica member produced by the method that does not emit yellow fluorescence at a wavelength of 560-580 nm even when it is irradiated with an ultraviolet ray by an excimer laser or the like, and hence can suitably be used for optical applications using as a light source high energy ultraviolet rays such as those from excimer lasers, typically KrF and ArF excimer lasers, for example, use as a lens material for steppers and the like as well as an optical member such as lenses and photomasks for excimer laser produced from the synthetic fused silica material.