Substrate material for X-ray optical components
View Patent ↗There is provided a substrate material for an optical component for X-rays of wavelength λ R . The substrate includes (a) a glass phase made of amorphous material having a positive coefficient of thermal expansion, and (b) a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 4 λ R . The substrate material has a stoichiometric ratio of the crystal phase to the glass phase such that a coefficient of thermal expansion of the substrate material is less than about 5×10 −6 K −1 in a temperature range of about 20 °C. to 100°C. The substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms.
1. A substrate material for an optical component for X-rays of wavelength λ R , comprising:
a glass phase made of amorphous material having a positive coefficient of thermal expansion; and
a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 4 λ R ,
wherein said substrate material has a stoichiometric ratio of said crystal phase to said glass phase such that a coefficient of thermal expansion of said substrate material is less than about 5×10 −6 K −1 in a temperature range of about 20° C. to 100° C., and
wherein said substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms.
2. The substrate material of claim 1 , wherein said coefficient of thermal expansion of said substrate material is less than about 1×10 −6 K −1 in said temperature range.
3. The substrate material of claim 1 , wherein said mean size is less than about 2 λ R .
4. The substrate material of claim 1 , wherein said mean size is less than about λ R .
5. The substrate material of claim 16 , wherein said mean size is less than about 2λ R /3.
6. The substrate material of claim 1 , wherein said mean size is less than about λ R /2.
7. The substrate material of claim 1 , wherein said HSFR is less than about λ R /50 rms.
8. The substrate material of claim 1 , wherein said HSFR is less than about λ R /100 rms.
9. The substrate material of claim 1 , wherein said wavelength λ R is in a range of about 10 nm to 30 nm.
10. The substrate material of claim 1 , wherein said surface treatment includes superpolishing a surface of said substrate material, and thereafter, beam processing said surface.
11. The substrate material of claim 1 , wherein said substrate material has a low spatial frequency roughness in a range of about λ R /50 to λ R /100 rms.
12. The substrate material of claim 1 , wherein said substrate material has a middle spatial frequency roughness (MSFR) in a range of about λ R /50 to λ R /100 rms.
13. The substrate material of claim 12 , wherein said MSFR is achieved by beam processing a surface of said substrate material.
14. The substrate material of claim 1 , wherein said optical component is a reticle mask.
15. The substrate material of claim 1 , wherein said optical component is a normal-incidence mirror providing reflectivity of greater than about 70% to said X-rays at non-grazing incidence.
16. The substrate material of claim 15 , wherein said normal-incident mirror has an aspherical shape.
17. The substrate material of claim 1 , further comprising a layered pair of materials thereon selected from the group consisting of Mo/Si, Mo/Bi, and MoRu/Be.
18. The substrate material of claim 17 , comprising about 40 to 200 layers of said layered pairs of material.
19. A substrate material for an optical component for X-rays of wavelength 10 nm≦λ R <30 nm comprising:
a glass phase made of amorphous material having a positive coefficient of thermal expansion; and
a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 38 nm,
wherein said substrate material has a stoichiometric ratio of said crystal phase to said glass phase such that a coefficient of thermal expansion of said substrate material is less than about 5×10 −6 K −1 in a temperature range of about 20° C. to 100° C., and
wherein said substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms.
20. The substrate material of claim 19 , wherein said mean size is less than about 20 nm.
21. The substrate material of claim 19 , wherein said mean size is less than about 10 nm.
22. An optical component for X-rays of wavelength λ R , comprising:
a substrate material that includes:
a glass phase made of amorphous material having a positive coefficient of thermal expansion; and
a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 4 λ R ,
wherein said substrate material has a stoichiometric ratio of said crystal phase to said glass phase such that a coefficient of thermal expansion of said substrate material is less than about 5×10 −6 K −1 in a temperature range of about 20° C. to 100° C., and
wherein said substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms.
23. The optical component of claim 22 , wherein said optical component is a mirror selected from the group consisting of a normal-incidence mirror and a grazing-incidence mirror.
24. The optical component of claim 22 , wherein said optical component is a reticle mask.
25. An EUV projection system, comprising:
an illumination system for illuminating a mask; and
a projection lens system for projecting an image of said mask,
wherein at least one of said illumination system or said projection lens system includes an optical component for X-rays of wavelength λ R having a substrate material that includes (a) a glass phase made of amorphous material having a positive coefficient of thermal expansion, and (b) a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 4 λ R ,
wherein said substrate material has a stoichiometric ratio of said crystal phase to said glass phase such that a coefficient of thermal expansion of said substrate material is less than about 5×10 −6 K −1 in a temperature range of about 20° C. to 100° C., and
wherein said substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms.
26. A system comprising a substrate material that includes:
a glass phase made of amorphous material having a positive coefficient of thermal expansion; and
a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 4 λ R ,
wherein said substrate material has a stoichiometric ratio of said crystal phase to said glass phase such that a coefficient of thermal expansion of said substrate material is less than about 5×10 −6 K −1 in a temperature range of about 20° C. to 100° C.,
wherein said substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms, and
wherein said system is selected from the group consisting of an X-ray microscopy system, an X-ray astronomy system, and X-ray spectroscopy system.
27. A substrate material for an optical component for X-rays of wavelength 10 nm≦λ R ≦30 nm, comprising:
an amorphous material having a positive coefficient of thermal expansion; and
crystallites having a negative coefficient of thermal expansion and being a mean size of less than about 38 nm,
wherein the substrate material has a coefficient of thermal expansion of less than about 5×10 −6 K −1 in a temperature range of about 20° C. to 100° C., and
wherein the substrate material has a high spatial frequency roughness (HSFR) of less than about λ R /30 rms.
28. The substrate material of claim 27 , wherein the substrate material has a middle spatial frequency roughness (MSFR) in a range of about λ R /50 to λ R /100 rms, and a low spatial frequency roughness in a range of about λ R /50 to λ R /100 rms.