Catadioptric imaging systems for digital scanner

• US 9,703,085 B2
• Filed: 12/03/2014
• Issued: 07/11/2017
• Est. Priority Date: 11/22/2013
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Williamson, David M.
• Primary Examiner(s): Mack, Ricky
• Assistant Examiner(s): Deherrera, Kristina
• Application Number:
  US14/559,684
• Publication Number:
  US 20150146185A1
• Time in Patent Office: 951 Days
• Field of Search: 359355
• CPC Class Codes: G02B 17/0816 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0892 specially adapted for the UV
• CPC Class Codes: G02B 27/0031 for scanning purposes
• CPC Class Codes: G03F 7/70225 Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements

Abstract

Projection optical system for forming an image on a substrate and including an illumination relay lens and a projection lens each of which is a catadioptric system. The projection lens may include two portions in optical communication with one another, the first of which is dioptric and the second of which is catadioptric. In a specific case, the projection optical system satisfies

$4<\frac{{\beta }_I}{{\beta }_T}<30,$
where β_I and β_T are magnifications of the first portion and the overall projection lens. Optionally, the projection lens may be structured to additionally satisfy

$6<\frac{{\beta }_{\mathrm{II}}}{{\beta }_T}<20,$
where β_II is a magnification of the second portion. A digital scanner including such projection optical system and operating with UV light having a spectral bandwidth on the order of 1 picometer. Method for forming an image with such projection optical system.

Claims

1. A projection optical system configured to form an image on an image plane, comprising:

a first optical system that includes first and second negative lenses and a concave mirror to form an intermediate optical image;

a second optical system configured as a dioptric optical system disposed to form an image of said intermediate optical image at the image plane;

wherein the first negative lens has concave and convex surfaces, said concave surface of the first negative lens facing away from the concave mirror; and

wherein a concave surface of the second negative lens is immediately adjacent to the concave mirror.

2. A projection optical system according to claim 1,

wherein said first optical system is positioned such that light directed through the projection optical system towards the image plane passes through the first negative lens, then through a second negative lens, and then is reflected with a concave mirror to form a reflected beam thither transmitted sequentially through the second and first negative lenses.

3. A projection optical system according to claim 1, wherein the-second optical system comprises at least two positive lenses disposed immediately adjacent to one another such as to receive light directly from said location.

4. A projection optical system according to claim 3, wherein the second optical system further comprises at least two negative lenses disposed immediately adjacent to one another between said at least two positive lenses and the image plane.

5. A projection optical system according to claim 4, wherein the second optical system further comprises a light-condensing lens unit between the at least two negative lenses and the image plane.

6. A projection optical system according to claim 5, wherein every lens of the light-condensing lens-unit is a positive lens.

7. A projection optical system according to claim 1, characterized, in operation with light having a central wavelength of about 193.3 nm and a spectral bandwidth of about 1 picometer, a first Strehl ratio at the central wavelength and a second Strehl ratio across the spectral bandwidth, both the first and second Strehl ratios exceeding 0.95.

8. A projection optical system according to claim 1, configured to form the image on the image plane with a reduction ratio of at least 50.

9. A projection optical system configured to form an image on an image plane, comprising:

a catadioptric projection lens including first and second portions in optical communication with one another;

said second portion configured as a catadioptric optical system designed to form an intermediate optical image at a location between elements of the second portion;

said first portion configured as a dioptric optical system disposed between the second portion and the image plane of the projection optical system to transfer light from said location to the image plane to form the image thereon,

said catadioptric projection lens configured to satisfy a condition of

10. A projection optical system according to claim 9, further comprising a catadioptric illumination relay lens and a spatial light modulator (SLM) positioned to receive light from the catadioptric illumination relay lens and reflect said light towards the catadioptric projection lens.

11. A projection optical system according to claim 9,

said catadioptric projection lens is configured to satisfy a condition of

12. A projection optical system according to claim 9,

wherein said catadioptric projection lens is configured to satisfy a condition of |β

_II|<

|β

_I|, wherein β

_I denotes a magnification of the first portion and β

_II denotes a magnification of the second portion.

13. A projection optical system according to claim 9,

wherein said second portion configured such that said light directed through the projection optical system towards the image plane passes through a first group of lenses including a first negative lens, then through a second group of lenses, and then is reflected with a concave mirror to form a reflected beam transmitted through the second group of lenses.

14. A projection optical system according to claim 13, wherein the second group of lenses includes second and third negative lenses immediately adjacent to one another, a concave surface of the second negative lens facing away from the concave mirror, a concave surface of the third negative lens facing the concave mirror.

15. A projection optical system according to claim 14, wherein the second group of lenses further comprises a positive lens between the first group of lenses and the third negative lens.

16. A projection optical system according to claim 9, wherein the first portion comprises at least two positive lenses disposed immediately adjacent to one another such as to receive light directly from said location.

17. A projection optical system according to claim 16, wherein the first portion further comprises at least two negative lenses disposed immediately adjacent to one another between said at least two positive lenses and the image plane.

18. A projection optical system according to claim 17, wherein the first portion further comprises a light-condensing lens unit between the at least two negative lenses and the image plane.

19. A projection optical system according to claim 18, wherein every lens of the light-condensing lens-unit is a positive lens.

20. A projection optical system according to claim 9, characterized, in operation with light having a central wavelength of about 193.3 nm and a spectral bandwidth of about 1 picometer, a first Strehl ratio at the central wavelength and a second Strehl ratio across the spectral bandwidth, both the first and second Strehl ratios exceeding 0.95.

21. A projection optical system according to claim 9, configured to form the image with a reduction ratio of at least 50.

22. An exposure apparatus configured to expose a substrate to light delivered thereto through liquid from an object, said exposure apparatus comprising:

a stage configured to support of a substrate defining the image plane; and

the projection optical system according to claim 9, said projection optical system configured to form said image on the substrate with light transmitted from an object through the projection optical system and liquid below the projection optical system.

23. An exposure apparatus according to claim 21, further comprising an illumination relay lens disposed to illuminate the object with light passing therethrough.

24. An exposure apparatus according to claim 23, wherein said illumination relay lens includes a catadioptric illumination relay lens.

25. A method for manufacturing a device, the method comprising:

exposing a substrate with light delivered thereto from an object through liquid with the use of the projection optical system according to claim 9, and

developing said substrate after exposure with said light.

26. A projection optical system according to claim 25,

wherein said second portion is positioned such that light directed through the projection optical system towards the image plane passes through the first negative lens, then through a second negative lens, and then is reflected with a concave mirror to form a reflected beam further transmitted sequentially through the second and first negative lenses.

27. A projection optical system according to claim 25, wherein the first portion comprises at least two positive lenses disposed immediately adjacent to one another such as to receive light directly from said location.

28. A projection optical system according to claim 27, wherein the first portion further comprises at least two negative lenses disposed immediately adjacent to one another between said at least two positive lenses and the image plane.

29. A projection optical system according to claim 27, wherein the first portion further comprises a light-condensing lens unit between the at least two negative lenses and the image plane.

30. A projection optical system according to claim 29, wherein every lens of the light-condensing lens-unit is a positive lens.

31. A projection optical system according to claim 25, characterized, in operation with light having a central wavelength of about 193.3 nm and a spectral bandwidth of about 1 picometer, a first Strehl ratio at the central wavelength and a second Strehl ratio across the spectral bandwidth, both the first and second Strehl ratios exceeding 0.95.

32. A projection optical system configured to form an image on an image plane, comprising:

a catadioptric projection lens including first and second portions in optical communication with one another;

said second portion configured as a catadioptric optical system that includes first and second negative lenses and a concave mirror to form an intermediate optical image at a location between elements of the second portion;

said first portion configured as a dioptric optical system and disposed between the image plane and the second optical portion to form an image of said intermediate optical image at the image plane;

wherein the first negative lens has concave and convex surfaces, said concave surface of the first negative lens facing away from the concave mirror; and

wherein a concave surface of the second negative lens is immediately adjacent to the concave mirror.

33. A projection optical system according to claim 32, configured to form the image with a reduction ratio of at least 50.