Silica glass containing TiO2 and optical material for EUV lithography

• US 20050245383A1
• Filed: 07/06/2005
• Published: 11/03/2005
• Est. Priority Date: 04/03/2003
• Status: Active Grant

• Current Assignee: AGC, Inc.
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Koike, Akio, Iwahashi, Yasutomi
• Granted Patent: US 7,462,574 B2
• Time in Patent Office: Days
• US Class Current: 501/54
• CPC Class Codes: C03B 19/1484 Means for supporting, rotating or translating the article being formed
• CPC Class Codes: C03B 2201/42 doped with titanium
• CPC Class Codes: C03C 2201/42 containing titanium
• CPC Class Codes: C03C 3/06 with more than 90% silica by weight, e.g. quartz C03C3/045 takes precedence
• CPC Class Codes: C03C 4/0085 for UV-transmitting glass

Abstract

A silica glass containing TiO₂, characterized in that the fluctuation of the refractive index (Δn) is at most 2×10⁻⁴ within an area of 30 mm×30 mm in at least one plane.

A silica glass containing TiO₂, characterized in that the TiO₂ concentration is at least 1 mass %, and the striae pitch is at most 10 μm.

An optical material for EUV lithography, characterized in that it is made of a silica glass containing TiO₂, and the fluctuation of the refractive index (Δn) is at most 2×10⁻⁴ in a plane perpendicular to the incident light direction.

An optical material for EUV lithography, characterized in that it is made of a silica glass containing TiO₂, wherein the TiO₂ concentration is at least 1 mass %, and the difference between the maximum value and the minimum value of the TiO₂ concentration is at most 0.06 mass % in a plane perpendicular to the incident light direction.

Claims

1. A silica glass containing Ti)₂, characterized in that the fluctuation of the refractive index (Δ

n) is at most 2×

10<sup>−

4</sup> within an area of 30 mm×

30 mm in at least one plane.

2. The silica glass containing TiO₂ according to claim 1, wherein the fluctuation of the refractive index (Δ

n) is at most 2×

10<sup>−

4</sup> within an area of 30 mm×

30 mm in each of two orthogonal planes.

6. The silica glass containing TiO₂ according to claim 1, wherein the striae pitch is at most 10 μ

m.

11. The optical material for EUV lithography according to claim 1, wherein the striae pitch is at most 10 μ

m.

12. An optical material for EUV lithography employing the silica glass containing TiO₂, as defined in claim 1.

13. The silica glass containing TiO₂ according to claim 2, wherein the striae pitch is at most 10 μ

m.

3. A silica glass containing TiO₂, characterized in that the TiO₂ concentration is at least 1 mass %, and the difference between the maximum value and the minimum value of the TiO₂ concentration is at most 0.06 mass % within an area of 30 mm×

30 mm in at least one plane.

4. The silica glass containing TiO₂ according to claim 3, wherein the difference between the maximum value and the minimum value of the TiO₂ concentration is at most 0.06 mass % within an area of 30 mm×

30 mm in each of two orthogonal planes.

14. The silica glass containing TiO₂ according to claim 3, wherein the striae pitch is at most 10 μ

m.

15. The silica glass containing TiO₂ according to claim 4, wherein the striae pitch is at most 10 μ

m.

16. The optical material for EUV lithography according to claim 3, wherein the striae pitch is at most 10 μ

m.

18. An optical material for EUV lithography employing the silica glass containing TiO₂, as defined in claim 3.

5. A silica glass containing TiO₂, characterized in that the TiO₂ concentration is at least 1 mass %, and the striae pitch is at most 10 μ

m.

7. An optical material for EUV lithography, characterized in that it is made of a silica glass containing TiO₂, and the fluctuation of the refractive index (Δ

n) is at most 2×

10<sup>−

4</sup> in a plane perpendicular to the incident light direction.

8. The optical material for EUV lithography according to claim 7, wherein there is no striae which cause a fluctuation of the refractive index (Δ

n) exceeding 2×

10<sup>−

4</sup> in a plane perpendicular to the incident light direction.

17. The optical material for EUV lithography according to claim 7, wherein the striae pitch is at most 10 μ

m.

19. An optical material for EUV lithography employing the silica glass containing TiO₂, as defined in claim 7.

9. An optical material for EUV lithography, characterized in that it is made of a silica glass containing TiO₂, wherein the TiO₂ concentration is at least 1 mass %, and the difference between the maximum value and the minimum value of the TiO₂ concentration is at most 0.06 mass % in a plane perpendicular to the incident light direction.

10. The optical material for EUV lithography according to claim 9, wherein there is no striae which cause a difference between the maximum value and the minimum value of the TiO₂ concentration, exceeding 0.06 mass % in a plane perpendicular to the incident light direction.