Glass ceramic product with variably adjustable zero crossing of the CTE-T curve

Abstract

The present invention relates to a process for producing a glass-ceramic with a defined zero crossing of the CTE-T curve (CTE: coefficient of thermal expansion), and glass-ceramic products produced using the process according to the invention.

1 . A process for producing a glass-ceramic which has a zero crossing of the CTE-T curve at a selected temperature T A ±10° C., comprising the steps of providing a glass-ceramic or a green body of a glass-ceramic and ceramicizing in accordance with a ceramicizing program, the determination of which comprises the step of determining the CTE-T curve.  
     
     
         2 . The process as claimed in  claim 1 , in which a Δl/l 0 -T set of curves is compiled in order to determine the ceramicizing program.  
     
     
         3 . The process as claimed in  claim 1 , in which the determination of the CTE-T curve comprises the following steps: 
 providing a green body or a pre-ceramicized glass-ceramic,    determining Δl/l 0 -T measurement points for the glass-ceramic in a temperature range T A ±50° C.    matching a polynomial to the Δl/l 0 -T measurement points, and    deriving the polynomial to obtain a CTE-T curve.    
     
     
         4 . The process as claimed in  claim 1 , in which the zero crossing of the CTE-T curve is set at T A ±7° C.  
     
     
         5 . The process as claimed  claim 1 , in which the zero crossing of the CTE-curve is set at T A ±5° C.  
     
     
         6 . The process as claimed in one of the preceding claims, in which a glass-ceramic belonging to the Li 2 O—Al 2 O 3 —SiO 2  system is provided.  
     
     
         7 . The process as claimed in  claim 1 , in which ceramicizing is carried out at a temperature at which the mean CTE [T A −50;T A +50] substantially does not change.  
     
     
         8 . The process as claimed in  claim 1 , in which a glass-ceramic with a mean CTE [(T A −50° C.);(T A +50° C.)] of at most 1.0×10 −6 /K is provided.  
     
     
         9 . The process as claimed in  claim 1 , in which the glass-ceramic is ceramicized in at least two ceramicizing steps.  
     
     
         10 . The process as claimed in  claim 1 , in which the glass-ceramic is ceramicized from the green body in one ceramicizing step.  
     
     
         11 . A glass-ceramic product with a zero crossing of the CTE-T curve at a temperature T A ±10° C., where T A  is a temperature from 0 to 100° C.  
     
     
         12 . The glass-ceramic product as claimed in  claim 11 , having a zero crossing of the CTE-T curve at a temperature T A ±7° C.  
     
     
         13 . The glass-ceramic product as claimed in  claim 11 , having a zero crossing of the CTE-T curve at a temperature T A ±50° C.  
     
     
         14 . The glass-ceramic product as claimed in  claim 11 , in which the glass-ceramic is from the Li 2 O—Al 2 O 3 —SiO 2  system.  
     
     
         15 . A substrate for EUV lithography, comprising a glass-ceramic product with a zero crossing of the CTE-T curve at a temperature T A ±10° C., where T A  is a temperature from 0 to 100° C.  
     
     
         16 . The substrate as claimed in  claim 15 , in which T A  lies in a range from 0 to 50° C.  
     
     
         17 . The substrate as claimed in  claim 16 , in which T A  lies in a range from 19 to 31° C.  
     
     
         18 . The substrate as claimed in  claim 15 , having a zero crossing of the CTE-T curve at a temperature T A ±3° C.  
     
     
         19 . The use of the process as claimed in one of  claims 1  to  10  for producing a glass-ceramic product for metrology, astronomy or microlithography.