Fused silica article loaded with deuterium and method of making

Abstract

A method of making a fused silica article having a combined concentration of protium and deuterium in a range from about 1×10 16 molecules/cm 3 up to about 6×10 19 molecules/cm 3 . In some embodiments, deuterium is present in an amount greater than its natural isotopic abundance. The method includes the steps of providing a fused silica boule, diffusing at least one of protium and deuterium into the boule, and annealing the boule to form the fused silica article. A method of diffusing hydrogen into fused silica and a fused silica article loaded with hydrogen formed by the method are also described.

1 . A fused silica article, the fused silica article having a combined concentration of protium and deuterium in a range from about 1×10 16  molecules/cm 3  up to about 6×10 19  molecules/cm 3  and a concentration of hydroxyl groups of less than about 100 ppm by weight, wherein deuterium is present in a concentration that is greater than its natural isotopic abundance. 
   
   
       2 . The fused silica article according to  claim 1 , wherein deuterium comprises at least 10% of the combined concentration. 
   
   
       3 . The fused silica article according to  claim 1 , wherein the combined concentration of protium and deuterium is in a range from about 0.1×10 17  molecules/cm 3  up to about 1×10 17  molecules/cm 3 . 
   
   
       4 . The fused silica article according to  claim 1 , wherein the fused silica article is formed by exposing the fused silica boule to at least one pulse of a first deuterium pressure, wherein each pulse has a first predetermined duration time, and wherein the first deuterium pressure is greater than ambient pressure, and exposing the fused silica boule to a second deuterium pressure immediately after each pulse for a second predetermined duration time, wherein the second deuterium pressure is less than the first deuterium pressure. 
   
   
       5 . The fused silica article according to  claim 4 , wherein the first deuterium pressure is in a range from about 1 atm up to about 150 atm. 
   
   
       6 . The fused silica article according to  claim 1 , wherein the fused silica article is an optical component in a photolithography apparatus. 
   
   
       7 . A method of making a fused silica article, the method comprising the steps of:
 a. providing a fused silica boule, wherein the fused silica boule has been consolidated, and wherein the fused silica boule has a concentration of hydroxyl groups of less than about 100 ppm by weight;   b. diffusing the deuterium into the fused silica boule at a predetermined temperature, wherein the deuterium is present in an amount that is greater than its natural isotopic abundance; and   c. annealing the fused silica boule after diffusing the deuterium into the fused silica boule at a predetermined annealing temperature to form the fused silica article, wherein the fused silica article has a combined concentration of protium and deuterium in a range from about 1×10 16  molecules/cm 3  up to about 6×10 19  molecules/cm 3 , and wherein deuterium is present in a concentration that is greater than its natural isotopic abundance.   
   
   
       8 . The method according to  claim 7 , wherein the step of diffusing deuterium into the fused silica boule at a predetermined temperature comprises exposing the fused silica boule to at least one pulse of a first deuterium pressure, wherein each pulse has a predetermined duration time, and wherein the deuterium pressure is greater than ambient pressure, and exposing the fused silica boule to a second deuterium pressure immediately after each pulse for a second duration time, wherein the second deuterium pressure is less than the first deuterium pressure. 
   
   
       9 . The method according to  claim 8 , wherein the first deuterium pressure is in a range from about 1 atm up to about 150 atm. 
   
   
       10 . The method according to  claim 8 , wherein the step of exposing the fused silica boule to at least one pulse of a deuterium pressure is repeated for a predetermined time period, wherein the predetermined time period is sufficient to load a region of the fused silica boule with the combined concentration of protium and deuterium. 
   
   
       11 . The method according to  claim 7 , wherein the step of diffusing deuterium into the fused silica boule comprises exposing the fused silica boule to an atmosphere having a combined concentration of protium and deuterium in a range from about 1% up to about 100%. 
   
   
       12 . The method according to  claim 11 , wherein the atmosphere comprises nitrogen and about 4% deuterium. 
   
   
       13 . The method according to  claim 8 , wherein deuterium comprises at least 10% of the combined concentration. 
   
   
       14 . The method according to  claim 7 , wherein the predetermined temperature is in a range from about 350° C. up to about 700° C. 
   
   
       15 . The method according to  claim 14 , wherein the predetermined temperature is in a range from about 400° C. up to about 500° C. 
   
   
       16 . The method according to  claim 7 , wherein the combined concentration of protium and deuterium is in a range from about 0.1×10 17  molecules/cm 3  up to about 1×10 17  molecules/cm 3 . 
   
   
       17 . A method of making a fused silica article, the method comprising the steps of:
 a. providing a fused silica boule, wherein the fused silica boule has been consolidated, and wherein the fused silica boule has a concentration of hydroxyl groups of less than about 100 ppm by weight;   b. exposing the fused silica boule to at least one pulse of a first deuterium pressure, wherein each pulse has a predetermined duration time, and wherein the deuterium pressure is greater than ambient pressure,   c. exposing the fused silica boule to a second deuterium pressure immediately after each pulse for a second duration time, wherein the second deuterium pressure is less than the first deuterium pressure; and   d. annealing the fused silica boule after diffusing the deuterium at a predetermined annealing temperature to form the fused silica article, wherein the fused silica article has a combined concentration of protium and deuterium in a range from about 1×10 16  molecules/cm 3  up to about 6×10 19  molecules/cm 3 , and wherein deuterium is present in the fused silica article in a concentration that is great than its natural isotopic abundance.