Synthetic silica material with low fluence-dependent-transmission and method of making the same
Disclosed in the application are a synthetic silica glass having low fluence-dependent transmission, particularly at about 193 nm, and a process for making the same. The glass may desirably exhibit a low level of fluorescence at 290 and 390 nm when activated at about 248 nm. The glass may desirably exhibit low level of LIWFD, [SiH*] and/or [ODC].
1. A synthetic silica glass material consisting essentially of silica, OH groups, and H 2 and having an OH concentration of lower than about 900 ppm by weight, an H 2 level of about 1×10 16 to about 5×10 17 molecules/cm 3 , and a fictive temperature of less than 1070° C., wherein the silica glass material has a measured FDT (dK/dF) when exposed to excimer laser at about 193 nm of less than 5.0×10 −4 cm·pulse/mJ.
2. A synthetic silica glass material according to claim 1 , comprising OH in the amount by weight of about 10-500 ppm.
3. A synthetic silica glass material according to claim 1 , comprising OH in the amount by weight of about 100-700 ppm.
4. A synthetic silica glass material according to claim 1 exhibiting a bulk laser induced wavefront distortion, measured at 633 nm, of between about −1.0 and 1.0 nm/cm, when subject to 10 billion pulses of an excimer laser at about 193 nm having a fluence of approximately 70 μJ/cm 2 ·pulse and a pulse length of about 25 ns.
5. A synthetic silica glass material according to claim 1 exhibiting a normalized laser induced wave-front distortion L633 when subjected to excimer laser pulses at about 193 nm, measured at about 633 nm, wherein 0≦L633≦1.0.
6. A synthetic silica glass material according to claim 1 exhibiting a normalized laser induced wave-front distortion L193 when subjected to excimer laser pulses at about 193 nm, measured at about 193 nm, wherein 0≦L193≦1.0.
7. A synthetic silica glass material according to claim 5 , wherein the glass has an OH concentration of less than or equal to about 160 ppm by weight.
8. A synthetic silica glass material according to claim 6 , wherein the glass has an OH concentration of less than or equal to about 160 ppm by weight.
9. A process for hydrogen loading a transparent consolidated synthetic silica glass material consisting essentially of silica, OH groups, and H 2 and having an OH concentration of lower than or equal to about 900 ppm by weight, comprising annealing the synthetic silica glass material in an annealing step such that the synthetic silica glass material has a fictive temperature of less than 1070° C., and treating the glass in the presence of H 2 gas at a temperature lower than 700° C. to a loaded H 2 level between about 1×10 16 to about 5×10 17 molecules/cm 3 , such that the glass has a FDT of less than 5.0×10 −4 cm·pulse/mJ when exposed to excimer laser radiation at about 193 nm.
10. A process according to claim 9 , wherein the synthetic silica glass before hydrogen loading has an H 2 content lower than about 1.0×10 15 molecules/cm 3 .
11. A process according to claim 9 , wherein the synthetic silica glass is subject to an annealing step before the hydrogen loading treatment, such that the silica glass obtained has a fictive temperature between about 800-1070° C.
12. A process according to claim 9 , wherein the synthetic silica glass comprises OH in the amount by weight of from about 10 to about 500 ppm.
13. A process according to claim 9 , wherein before hydrogen loading, the synthetic silica glass has an H 2 level of less than about 1×10 16 molecules/cm 3 .