F-doped silica glass and process of making same
AssigneeCorning Incorporated
InventorsLisa Anne Moore, Charlene Marie Smith
Life of this patent
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Abstract
An F-doped silica glass, a process for making the glass, an optical member comprising the glass, and an optical system comprising such optical member. The glass material comprises 0.1-5000 ppm by weight of fluorine. The glass material according to certain embodiments of the present invention has low polarization-induced birefringence, low LIWFD and low induced absorption at 193 nm.
Claims24
An F-doped synthetic silica glass material capable of being used in the light path of the lithographic irradiation of a lithographic device operating at a wavelength below 300 nm, comprising, by weight of the glass:
- from 0.01 to 150 ppm OD;
- less than 50 ppm of Cl;
- less than 50 ppb of Na;
- less than 50 ppb in total of transition metals;
- and
- from 0.1 ppm to 5000 ppm of fluorine;
- and
- having a polarization-induced birefringence of lower than 7 nm/mm, measured at 633 nm after being subjected to 10 million pulses of linearly polarized pulsed laser beam at 157 nm having a fluence of 250 μJ·cm−2·pulse−1 and a pulse length of 30 ns.
An optical member for use in the optical path of irradiation having a wavelength shorter than 300 nm, consisting essentially of an F-doped synthetic silica glass material capable of being used in the light path of the lithographic irradiation of a lithographic device operating at a wavelength below 300 nm, comprising, by weight of the glass:
- from 0.01 to 150 ppm OD;
- less than 50 ppm of Cl;
- less than 50 ppb of Na;
- less than 50 ppb in total of transition metals;
- and
- from 0.1 ppm to 5000 ppm of fluorine;
- and
- having a polarization-induced birefringence of lower than 7 nm/mm, measured at 633 nm after being subjected to 10 million pulses of linearly polarized pulsed laser beam at 157 nm having a fluence of 250 μJ·cm−2·pulse−1 and a pulse length of 30 ns.
A lithographic system comprising at least one optical member consisting essentially of an F-doped synthetic silica glass material capable of being used in the light path of the lithographic irradiation of a lithographic device operating at a wavelength below 300 nm, comprising, by weight of the glass:
- from 0.01 to 150 ppm OD;
- less than 50 ppm of Cl;
- less than 50 ppb of Na;
- less than 50 ppb in total of transition metals;
- and
- from 0.1 ppm to 5000 ppm of fluorine;
- and
- having a polarization-induced birefringence of lower than 7 nm/mm, measured at 633 nm after being subjected to 10 million pulses of linearly polarized pulsed laser beam at 157 nm having a fluence of 250 μJ·cm−2·pulse−1 and a pulse length of 30 ns.
A process for making F-doped synthetic silica glass material capable of being used in the light path of the lithographic irradiation of a lithographic device operating at a wavelength below 300 nm, comprising the following steps:
- (A) providing a particle preform comprising a plurality of particles comprising silica;
- (B) optionally purifying and/or drying the particle preform;
- (C) optionally further doping the particle preform with dopants;
- (D) consolidating the particle preform at an elevated temperature to densified glass;
- and
- (E) optionally treating the consolidated glass obtained in step (D) in the presence of H2, HD and/or D2,
- wherein in at least one of steps (A), (B), (C) and (D), F is introduced or formed into the glass such that the resultant glass comprises F from 0.1 to 5000 ppm by weight of the glass, from 0.01 to 150 ppm OD, and wherein the glass comprises:
- less than 50 ppm of Cl;
- less than 50 ppb of Na;
- and less than 50 ppb in total of transition metals.
Dependencies are inferred from the claim text.