Abstract:
PROBLEM TO BE SOLVED: To provide a doped silica-titania glass that has the required improvements for certain parameters such as a tolerance value for Tzc, CTE vs. temperature slope and Tzc spatial homogeneity and is suitable for use in below 25 nm node lithography as an element of a system.SOLUTION: Selected weight of silica-titania powders and selected weight of dopant powders are weighed out and the silica-titania powders and the selected dopant powders are mixed for forming slurry of the mixed powders using a selected fluid. The slurry is sprayed and dried to form a powder containing free-flowing fine particles having a size of approximately 200 μm diameter or less. The powder is shaped into a shaped article by uniaxial pressing and then further by cold isostatic pressing. The shaped article is consolidated by hot pressing to shape into a doped silica-titania glass blank and further the glass blank is annealed.
Abstract:
A doped silica-titania glass article is provided that includes a glass article having a glass composition comprising (i) a silica-titania base glass, (ii) a fluorine dopant, and (iii) a second dopant. The fluorine dopant has a concentration of fluorine of up to 5 wt. % and the second dopant comprises one or more oxides selected from the group consisting of Al, Nb, Ta, B, Na, K, Mg, Ca and Li oxides at a total oxide concentration from 50 ppm to 6 wt.%. Further, the glass article has an expansivity slope of less than 0.5 ppb/K2 at 20⃘C. The second dopant can be optional. The composition of the glass article may also contain an OH concentration of less than 100 ppm.