B-quartz glass-ceramic extreme ultraviolet optical elements and a method of making them
OwnerAdam Ellison, Philip Fenninventors
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Abstract
The invention is directed to a glass-ceramic material suitable for use in the manufacturing of EUVL reflective optics. The glass-ceramic materials is made from a composition that comprises (in wt. %): SiO2=64-70; Al2O3=18-24; Li2O=1.6-3.8; MgO=0.8-1.5; ZnO=0.7-4.2; BaO=0.1-1.4; TiO2=2.0-3.5; ZrO2=1.25-2.5; As2O3=0.1-1.0; Na2O<0.5; and K2O<0.5; and the glass-ceramic material has an aggregate coefficient of thermal expansion of ±1 ppm/° C. (±0.1×10−7/° C.) in the temperature range 0-200° C.
Claims9
A glass-ceramic material suitable for use in the manufacturing of EUVL reflective optics, said glass-ceramic being made from a composition comprising (in wt. %):
- SiO2 64-70
- Al2O3 18-24
- Li2O 1.6-3.8
- MgO 0.8-1.5
- ZnO 0.7-4.2
- BaO 0-1.4
- TiO2 2.0-3.5
- ZrO2 1.25-2.5
- As2O3 0-1.0
- Na2O <0.5
- K2O <0.5
- Wherein said glass-ceramic material has an aggregate coefficient of thermal expansion of 0±0.5×10−7/° C. in the temperature range 0-200° C.
A method for preparing glass-ceramic materials suitable for EUVL applications, said method comprising the steps of:
- (a) preparing a green glass composition comprised of:
- SiO2 64-70
- Al2O3 18-24
- Li2O 1.6-3.8
- MgO 0.8-1.5
- ZnO 0.7-4.2
- BaO 0.1-1.4
- TiO2 2.0-3.5
- ZrO2 1.25-2.5
- As2O3 0.1-1.0
- Na2O <0.5
- K2O <0.5
- (b) milling the composition for a time in the range of 1-3 hours;
- (c) transferring the milled composition to a vessel;
- (d) placing the vessel in a furnace at a temperature of 1550±5° C. to melt the composition and holding the composition in the furnace for a time in the range of 14-18 hours;
- (e) heating the melted composition to approximately 1650±10° C. and holding the composition at temperature for a time in the range of 3-6 hours;
- (f) transferring the melt composition to a form and, once the melt has set, transferring the form containing the set melt to an annealing furnace at a temperature of 650±25° C. and holding at this temperature for a time in the range of 1-3 hours;
- (g) slowly cooling the melt to room temperature;
- (h) placing the cooled, annealed material to a ceramming furnace;
- and ceramming according to the schedule:
- Starting Temp
- Final Temp
- ramp rate
- Hold Time
- (° C.)
- (° C.)
- (° C./minute)
- (Hours)
- 18-50
- 720 ± 20
- 0.5
- ≧4 to 8
- 720 ± 20
- 820 ± 20
- 1
- ≧4 to 40
- 820 ± 20
- T
- 0.1-0.05
- 0
- T
- 22
- 0.2
- end
- T = 700 ± 30° C.
- to thereby make a glass-ceramic material suitable for use in reflective EUVL applications.
A substrate suitable for use as a substrate to extreme ultraviolet lithographic reflective elements, said substrate comprising:
- a cerammed material of composition
- SiO2 64-70
- Al2O3 18-24
- Li2O 1.6-3.8
- MgO 0.8-1.5
- ZnO 0.7-4.2
- BaO 0.1-1.4
- TiO2 2.0-3.5
- ZrO2 1.25-2.5
- As2O3 0.1-1.0
- Na2O <0.5
- K2O <0.5
- wherein said cerammed material has a CTE of 0±0.5×10−7/° C.
Dependencies are inferred from the claim text.