Objectives as a microlithography projection objective with at least one liquid lens
View Patent ↗The invention relates to an objective designed as a microlithography projection objective for an operating wavelength. The objective has a greatest adjustable image-side numerical aperture NA, at least one first lens made from a solid transparent body, in particular glass or crystal, with a refractive index n L and at least one liquid lens (F) made from a transparent liquid, with a refractive index NF. At the operating wavelength the first lens has the greatest refractive index n L of all solid lenses of the objective, the refractive index n F of the at least one liquid lens (F) is bigger than the refractive index n L of the first lens and the value of the numerical aperture NA is bigger than 1.
1. A microlithography projection objective having a maximum adjustable image-side numerical NA bigger than 1, at least one first lens made from a solid transparent body with a refractive index n L , and at east one liquid lens made from a transparent liquid, with a refractive index n F ,
wherein, at an operating wavelength of the objective, the first lens has the greatest refractive index n L of all solid lenses of the objective, and the refractive index n F of the at least one liquid lens is bigger than the refractive index n L of the first lens, than 1.
2. The objective according to claim 1 , wherein, at the operative wavelength of the objective, n F >NA>n L .
3. The objective according to claim 1 , wherein, at the operating wavelength of the objective, NA≧1.4.
4. The objective according to claim 1 , wherein the at least one liquid lens is a last curved optical element on an image side of the objective.
5. The objective according to claim 1 , wherein a plane-parallel plate is arranged between the at least one liquid lens and an image plane of the objective.
6. The objective according to claim 5 , wherein, at the operating wavelength of the objective, the refractive index n EP of a plane-parallel is greater than the refractive index n F of the at least one liquid lens.
7. The objective according to claim 1 , wherein the at least one liquid lens is essentially hemispherical.
8. The objective according to claim 1 , wherein the objective exhibits one or two intermediate images.
9. The objective according to claim 1 , wherein the objective is catadioptric.
10. The objective according to claim 1 , wherein the objective comprises an image-side objective part arranged at an image-side end of the objective, the image-side objective part being refractive.
11. The objective according to claim 10 , wherein a pupil of the image-side objective part is arranged between a lens at which a traversing light bundle is of greatest diameter and the image plane.
12. The objective according to claim 1 , wherein a plurality of meniscus lenses of positive refractive power, which have a concave shape on an image side of the objective, precede the at least one liquid lens.
13. The objective according to claim 1 , wherein a stop-down system aperture is arranged in an object-side objective part of the objective, the object-side objective part being located at the object-side end of the objective.
14. The objective according to claim 1 , wherein, at the operating wavelength of the objective, the refractive index n F of the at least one liquid lens is bigger than 1.
15. The objective according to claim 1 , wherein the objective is a catadioptric objective for which all refracting or reflecting surfaces are rotationally symmetrical in relation to a common axis.
16. The objective according to claim 1 , wherein the objective is a catadioptric objective comprising a plurality of mirrors, and all the mirrors are curved.
17. The objective according to claim 1 , wherein the objective comprises a catoptric or catadioptric objective part.
18. The objective according to claim 1 , wherein the objective comprises a catadioptric objective part with a concave mirror and a negative lens.
19. The objective according to claim 1 , wherein the objective comprises an immersion objective.
20. The objective according to claim 1 , wherein at least one liquid lens touches an image plane and an object, if the object is arranged in the image plane.
21. The objective according to claim 1 , wherein the objective comprises an object-side last element made from a transparent solid body, and a transparent medium with a refractive index n I >1.1 at the element and an object in the region of the image plane.
22. The objective according to claim 21 , wherein, at the operating wavelength of the objective, n I =n F .
23. The objective according to claim 21 , wherein, at the operating wavelength of the objective, n I ≧n L .
24. Objective according to claim 21 , wherein a material of the first lens or further lenses is a material from the group of fused silica and fluoride monocrystals comprising CaF 2 , BaF 2 , SrF 2 , LiF, NaF.