Projection objective
View Patent ↗The disclosure relates a projection objective for imaging an object field in an object plane into an image field in an image plane. The disclosure also relates to a microlithographic projection exposure apparatus including such a projection objective. The disclosure further relates to methods of using such a projection exposure apparatus to fabricate microstructured or nanostructured components, such as highly integrated semiconductor components. In addition, the disclosure relates to components fabricated by such methods.
1. A projection objective configured to image radiation from an object field in an object plane to an image field in an image plane along an optical path, the projection objective comprising:
a grazing incidence mirror configured to provide a first bundle-guiding element, the grazing incidence mirror being downstream of the object plane along the optical path; and
a normal incidence mirror disposed downstream of the grazing incidence mirror in the optical path,
wherein:
the grazing incidence mirror is closer to the object plane along the optical path than any other mirror in the projection objective; and
the projection objective is a microlithographic projection objective.
2. A projection objective according to claim 1 , wherein the projection objective has exactly six normal incidence mirrors.
3. A projection objective according to claim 1 , wherein there is an angle of greater than 20° between:
an object principal beam portion of a principal beam of a central object field point between the object field and the grazing incidence mirror; and
an image principal beam portion of the principal beam directly in front of the image plane.
4. A projection objective according to claim 1 , wherein the projection objective has a numerical aperture of 0.3 on the side of the image field.
5. A projection objective according to claim 1 , wherein the projection objective has an image field with a surface area of at least 1 mm 2 .
6. An apparatus, comprising:
an illumination system; and
a projection objective according to claim 1 ,
wherein the apparatus is a microlithographic projection exposure apparatus.
7. An apparatus according to claim 6 , wherein there is an angle of less than 60° between:
an axis portion of an optical axis, the axis portion being located between a last bundle-guiding element of the illumination system and the object plane; and
the image plane.
8. An apparatus according to claim 6 , wherein the illumination system comprises an additional grazing incidence mirror that is the last bundle-guiding element disposed upstream of the object plane in a beam path of the illumination light.
9. An apparatus according to claim 8 , wherein there is an angle less than 45° between:
an axis portion of an optical axis, the axis portion being located between a last bundle-guiding element of the illumination system and the additional grazing incidence mirror; and
the image plane.
10. An apparatus according to claim 6 , wherein an angle of incidence of the illumination light on the grazing incidence mirror is greater than 70°.
11. An apparatus according to claim 6 , wherein the angle of incidence of the illumination light on the grazing incidence mirror is greater than 80°.
12. An apparatus according to claim 6 , wherein the grazing incidence mirror has a reflecting freeform surface.
13. An apparatus according to claim 6 , wherein the projection objective has a root mean square wavefront error that is less than 15 mλ.
14. An apparatus according to claim 13 , wherein the root mean square wavefront error is 5 mλ.
15. A method, comprising:
using the apparatus of claim 6 to fabricate a microstructured component.
16. The method of claim 15 , wherein the method comprises:
imaging a pattern of a reticle via the projection exposure apparatus onto an illumination-light sensitive coating of a wafer.
17. A projection objective configured to image radiation from an object field in an object plane to an image field in an image plane along an optical path, the projection objective comprising:
a first mirror configured that the radiation impinges at grazing incidence along the optical path, the first mirror being downstream of the object plane along the optical path; and
a second mirror that the radiation impinges at a substantially normal angle along the path of the radiation, the second mirror being disposed downstream of the first mirror in the optical path,
wherein:
the first mirror is closer to the object plane along the optical path than any other mirror in the projection objective; and
the projection objective is a microlithographic projection objective;
a portion of the radiation that passes through a center of a pupil of the projection objective assigned to a central field point impinges on the first mirror at an angle of incidence of at least 70°; and
all individual rays of the radiation in the optical path that impinge on the second mirror do so at an angle of incidence that is less than 30°.
18. The projection objective of claim 17 , wherein the first mirror is configured to provide a first bundle-guiding element.
19. The projection objective of claim 17 , wherein the projection objective has exactly six normal incidence mirrors.
20. The projection objective of claim 17 , wherein the projection objective has a numerical aperture of 0.3 on the side of the image field.
21. The projection objective of claim 17 , wherein the projection objective has an image field with a surface area of at least 1 mm 2 .