Quartz glass blank for an optical component and its utilization

Abstract

The present invention concerns a quartz glass blank for an optical component for the transmission of ultraviolet radiation of a wave length of 250 nm and under, as well as its utilization in microlithography in connection with ultraviolet radiation of a wavelength of 250 nm and under. Such quartz glass blank is to have low induced absorption, while being optimized in respect of compaction and de-compaction. The quartz glass blank according to the invention has the following properties: A glass structure essentially free of oxygen defect sites; a H2 content in the range of 3×1017 molecules/cm3 to 2.0×1018 molecules/cm3; an OH content in the range of 500 weight ppm to 1000 weight ppm; a SiH group content of less than 2×1017 molecules/cm3; a chlorine content in the range of 60 weight ppm to 120 weight ppm; a refractive index inhomogeneity, Δn, of less than 2 ppm; and a stress birefringence of less than 2 nm/cm. For utilization according to the invention, the quartz glass blank—in respect of its minimum and maximum hydrogen content, CH2min and CH2max, as well as its OH content COH—is in accordance with the scaling laws (2), (3) and (4), and P standing for the pulse number and ε for the energy density: CH2min[molecules/cm3]=1.0×108ε2P ,   (2) CH2max[molecules/cm3]=2×1019ε,   (3) COH[weight ppm]=1700ε[mJ/cm2]0.4±50 .   (4)

Dependencies are inferred from the claim text.