Optical component made of quartz glass for use in ArF excimer laser lithography and method for producing the component
An optical component made of synthetic quartz glass includes a glass structure substantially free of oxygen defect sites and having a hydrogen content of 0.1×10 16 to 1.0×10 18 molecules/cm 3 , an SiH group content of less than 2×10 17 molecules/cm 3 , a hydroxyl group content of 0.1 to 100 wt. ppm, and an Active temperature of less than 1070° C. The optical component undergoes a laser-induced change in the refractive index in response to irradiation by a radiation with a wavelength of 193 nm using 5×10 9 pulses with a pulse width of 125 ns and a respective energy density of 500 μJ/cm 2 at a pulse repetition frequency of 2000 Hz. The change totals a first measured value M 193 nm when measured using the applied wavelength of 193 nm and a second measured value M 633 nm when measured using a measured wavelength of 633 nm. The ratio M 193 nm /M 633 nm is less than 1.7.
1. A method for producing optical component made of synthetic quartz glass for use in ArF excimer laser lithography with an applied wavelength of 193 nm, the method comprising the following steps:
a) producing a porous soot body of SiO 2 by flame hydrolysis of a silicon-containing starting substance;
b) drying the porous soot body;
c) treating the porous soot body in an oxidizing atmosphere containing N 2 O at a treatment temperature of less than 500° C. for at least 10 hours, a N 2 O content of the atmosphere being between 0.1 and 10 vol.-%;
d) subsequent sintering of the porous soot body, a hydroxyl group content in the porous soot body being set by drying according to step b) and by treatment according to step c) such that a semi-finished product of quartz glass is obtained, the semi-finished product having a mean hydroxyl group content in the range between 0.1 and 100 wt. ppm;
e) shaping the semi-finished product into a blank of quartz glass and annealing the blank; and
f) loading the blank with hydrogen by heating in a hydrogen-containing atmosphere at a temperature below 400° C. so as to produce a glass structure which is substantially free of oxygen defect sites,
wherein the glass structure has a hydrogen content in the range of 0.1×10 16 molecules/cm 3 to 1.0×10 18 molecules/cm 3 , a content of SiH groups of less than 2×10 17 molecules/cm 3 , a content of hydroxyl groups in the range between 0.1 and 100 wt. ppm, and a fictive temperature of less than 1070° C.,
wherein the glass structure reacts to irradiation with radiation of an applied wavelength of 193 nm with 5×10 9 pulses with a pulse width of 125 ns and an energy density of 500 μJ/cm2 each time and a pulse repetition frequency of 2000 Hz with a laser-induced refractive-index change, the amount of which upon measurement with the applied wavelength of 193 nm yields a first measured value M 193 nm and upon measurement with a measurement wavelength of 633 nm yields a second measured value M 633 nm , and
wherein M 193 nm /M 633 nm <1.7.
2. The method according to claim 1 , wherein the drying of the porous soot body according to step b) includes a treatment of the porous soot body at a drying temperature in the range between 1100° C. and 1350° C.
3. The method according to claim 1 , wherein the loading of the blank with hydrogen is carried out at a pressure between 1 and 150 bar.
4. The method according to claim 1 , wherein the loading of the blank with hydrogen is carried out at a temperature below 350° C.