Synthetic silica having low polarization-induced birefringence, method of making same and lithographic device comprising same
AssigneeCorning Incorporated
InventorsDouglas Alan, Dana Bookbinder, Ulrich Neukirch, Charlene Smith
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Abstract
Disclosed are synthetic silica glass having a low polarization-induced birefringence, process for making the glass and lithography system comprising optical element made of the glass. The silica glass has a polarization-induced birefringence measured at 633 nm of less than about 0.1 nm/cm when subjected to excimer laser pulses at about 193 nm having a fluence of about 40 μJ·cm−2·pulse−1 and a pulse length of about 25 ns for 5×109 pulses.
Claims32
A synthetic silica glass material capable of being used in the light path of lithographic irradiation at below about 300 nm in lithographic devices having less than about 1 nm/cm of polarization-induced birefringence measured at about 633 nm after being subjected to 5×109 pulses of linearly polarized pulsed laser beam at about 193 nm having a fluence of about 40 μJ·cm−2·pulse−1 and a pulse length of about 25 ns.
A synthetic silica glass material capable of being used in the light path of lithographic irradiation at below about 300 nm in lithographic devices, wherein the glass, when exposed to linearly polarized pulsed laser irradiation at about 193 nm, has a polarization-induced birefringence approximately meeting the following equation:
- PIB=a·F·N,
- where PIB is polarization-induced birefringence measured at about 633 nm, F is fluence of the 193 laser irradiation, N is pulse number in the million, and <5.0×10−7 cm2·μJ−1.
A synthetic silica glass material having a normalized polarization-induced birefringence measured at 633 nm of less than 10 when exposed to linearly polarized pulsed laser irradiation at about 193 nm.
A method for producing a synthetic silica glass material capable of being used in the light path of the lithographic irradiation below about 300 nm of a lithographic device having a low level of polarization-induced birefringence upon exposure to linearly polarized irradiation at about 193 nm, comprising the following steps:
- (i) providing a high purity consolidated synthetic silica glass material having OH concentration of less than about 500 ppm by weight;
- and
- (ii) treating the consolidated synthetic silica glass in the presence of H2 at a temperature below 800° C., at least if the consolidated glass provided in step (i) has an H2 concentration of less than 1×1016 molecules/cm3.
Dependencies are inferred from the claim text.