A process for the preparation of synthetic silica glass for use for arf - excimer - laser lithography

摘要

An object of the present invention is to provide a simple method for producing a synthetic quartz glass having excellent homogeneity and high transmittance, which is useful as an optical material in producing steppers equipped with an ArF excimer laser as a radiation source.;A method for producing a synthetic quartz glass for use in ArF excimer laser lithography, which comprises irradiating a highly homogeneous synthetic quartz glass containing less than 60 ppb of Na with an ultraviolet radiation having a maximum wavelength of 260 nm for not less than the duration expressed by the following equation 1:$\[ \text{Y = (80X - 1880)/Z} \]$ wherein X represents an Na concentration (ppb), Y represents the duration of irradiation (hours), and Z represents the illuminance of an ultraviolet radiation on an irradiated surface (mW/cm²).