Projection optics for microlithography
View Patent ↗A projection optics for microlithography, which images an object field in an object plane into an image field in an image plane, where the projection optics include at least one curved mirror and including at least one refractive subunit, as well as related systems, components, methods and products prepared by such methods, are disclosed.
1. A projection optics which images an object field in an object plane into an image field in an image plane, the projection optics comprising:
a curved mirror; and
a refractive subunit,
wherein a reflection surface of the mirror is configured as a static free-form surface which cannot be described by a rotationally symmetrical function, and the projection optics is configured to be used in microlithography.
2. The projection optics according to claim 1 , wherein the image plane is arranged parallel to the object plane.
3. The projection optics according to claim 1 , comprising an object/image offset which is less than 50 mm.
4. The projection optics according to claim 1 , wherein the intersection of an optical axis of the refractive subunit with the object plane is located in the object field.
5. The projection optics according to claim 4 , wherein the intersection of the optical axis of the refractive subunit with the object plane is centred in the object field.
6. The projection optics according to claim 1 , wherein the intersection of the optical axis of the refractive subunit with the image plane is located in the image field.
7. The projection optics according to claim 6 , wherein the intersection of the optical axis of the refractive subunit with the image plane is centred in the image field.
8. The projection optics according to claim 1 , wherein the projection optics comprises six mirrors.
9. The projection optics according to claim 1 , wherein the refractive subunit has at most eight lenses.
10. The projection optics according to claim 1 , comprising an image-side refractive subunit and an object-side refractive subunit, between which at least two mirrors are arranged, of which at least one has a free-form surface.
11. The projection optics according to claim 10 , wherein the intersection of the optical axis of the object-side refractive subunit with the object plane is located in the object field, and the intersection of the optical axis of the image-side refractive subunit with the image plane is located in the image field.
12. The projection optics according to claim 11 , wherein the intersection of the optical axis of the object-side refractive subunit with the object plane is centred in the object field, and the intersection of the optical axis of the image-side refractive subunit with the image plane is centred in the image field.
13. The projection optics according to claim 10 , wherein a principal ray of a central field point between two mirrors arranged between the object-side and image-side refractive subunits extends parallel to the optical axis of the object-side and image-side refractive subunits and set apart from this optical axis.
14. The projection optics according to claim 10 , wherein the optical axes of the object-side and image-side refractive subunits extend parallel and set apart from each other.
15. The projection optics according to claim 1 , further comprising at least one mirror which is deformable in the region of a pupil plane of the projection optics.
16. The projection optics according to claim 1 , wherein the projection optics is configured to illuminate an image field which is larger than 1 mm 2 .
17. The projection optics according to claim 1 , wherein the projection optics has an image-side numerical aperture of at least 0.5.
18. The projection optics according to claim 1 , wherein the projection optics is telecentric on at least one of the object and image sides.
19. The projection optics according to claim 1 , further comprising a light source configured to generate illumination light having a wavelength in the range of from 126 to 248 nm.
20. The projection optics according to claim 1 , wherein the projection optics has in the imaging beam path between the object plane and the image plane at least one intermediate image plane.
21. The projection optics according to claim 20 , wherein the refractive subunit is arranged between the intermediate image plane and the image plane.
22. A projection exposure system, comprising:
an illumination optics configured to guide illumination light toward an object field in an object plane; and
a projection optics according to claim 1 ,
wherein the projection exposure system is a microlithography projection exposure system.
23. A method, comprising:
projecting a structure of a reticle onto a light-sensitive layer of a wafer via a projection exposure system to produce a microstructured element,
wherein the projection exposure system comprises:
an illumination optics configured to guide illumination light toward an object field in an object plane; and
a projection optics according to claim 1 .