Microlithography projection objective
View Patent ↗Microlithography projection objectives for imaging into an image plane a pattern arranged in an object plane are described with respect to suppressing false light in such projection objectives.
1. A projection objective, comprising:
a plurality of optical elements configured to image a pattern in an object plane along a light path through the projection objective into an image plane, the plurality of optical elements comprising a lens;
a first stop; and
a second stop,
wherein:
along the light path, the only optical element between the first and second stops is the lens; and
the projection objective is a microlithography projection objective.
2. The projection objective of claim 1 , wherein the projection objective is a catadioptric projection objective.
3. The projection objective of claim 1 , wherein the first stop is configured to shield over-aperture light from the object plane.
4. The projection objective of claim 1 , wherein projection objective has a pupil plane, the first stop is an aperture stop, and the first stop is at or near the pupil plane.
5. The projection objective of claim 1 , wherein the first stop has an adjustable cross-section.
6. The projection objective of claim 1 , wherein:
the projection objective comprises first, second and third objective parts;
the second objective part is downstream of the first objective part along the light path;
the third objective part is downstream of the second objective part along the light path;
the projection objective comprises a beam deflecting device;
the beam deflecting device is between the first and second objective parts along the light path;
the beam deflecting device is between the second and third objective parts along the light path; and
the third objective part comprises the lens, the first stop and the second stop.
7. The projection objective of claim 6 , comprising a shield configured to suppress false light near a region where light passes twice during use of the projection objective.
8. The projection objective of claim 7 , wherein the lens is a negative lens.
9. The projection objective of claim 6 , further comprising an optical element comprising a coating configured to absorb false light.
10. The projection objective of claim 6 , further comprising a shield configured to reduce direct light leakage from the first objective part into the third objective part.
11. The projection objective of claim 1 , wherein:
the projection objective comprises first, second and third objective parts;
the second objective part is downstream of the first objective part along the light path;
the third objective part is downstream of the second objective part along the light path;
the projection objective comprises a beam deflecting device;
the beam deflecting device is between the first and second objective parts along the light path;
the beam deflecting device is between the second and third objective parts along the light path; and
the second objective part comprises the lens, the first stop and the second stop.
12. The projection objective of claim 11 , comprising a shield configured to suppress false light near a region where light passes twice during use of the projection objective.
13. The projection objective of claim 11 , further comprising an optical element comprising a coating configured to absorb false light.
14. The projection objective of claim 11 , further comprising a shield configured to reduce direct light leakage from the first objective part into the third objective part.
15. The projection objective of claim 1 , wherein the first stop comprises a light absorbing layer.
16. The projection objective of claim 1 , further comprising a mirror.
17. A projection objective, comprising:
a plurality of optical elements configured to image a pattern in an object plane along a light path through the projection objective into an image plane, the plurality of optical elements comprising a lens;
a first stop; and
a second stop,
wherein:
along the light path, the first stop is immediately upstream of the lens;
along the light path, the second stop is immediately downstream of the lens; and
the projection objective is a microlithography projection objective.
18. The projection objective of claim 17 , wherein the projection objective is a catadioptric projection objective.
19. The projection objective of claim 17 , wherein the first stop is configured to shield over-aperture light from the object plane.
20. The projection objective of claim 17 , wherein projection objective has a pupil plane, the first stop is an aperture stop, and the first stop is at or near the pupil plane.
21. The projection objective of claim 17 , wherein the first stop has an adjustable cross-section.
22. The projection objective of claim 17 , wherein:
the projection objective comprises first, second and third objective parts;
the second objective part is downstream of the first objective part along the light path;
the third objective part is downstream of the second objective part along the light path;
the projection objective comprises a beam deflecting device;
the beam deflecting device is between the first and second objective parts along the light path;
the beam deflecting device is between the second and third objective parts along the light path; and
the third objective part comprises the lens, the first stop and the second stop.
23. The projection objective of claim 22 , comprising a shield configured to suppress false light near a region where light passes twice during use of the projection objective.
24. The projection objective of claim 23 , wherein the lens is a negative lens.
25. The projection objective of claim 22 , further comprising an optical element having a coating configured to absorb false light.
26. The projection objective of claim 22 , further comprising a shield configured to reduce direct light leakage from the first objective part into the third objective part.
27. The projection objective of claim 17 , wherein the first stop comprises a light absorbing layer.
28. The projection objective of claim 17 , wherein:
the projection objective comprises first, second and third objective parts;
the second objective part is downstream of the first objective part along the light path;
the third objective part is downstream of the second objective part along the light path;
the projection objective comprises a beam deflecting device;
the beam deflecting device is between the first and second objective parts along the light path;
the beam deflecting device is between the second and third objective parts along the light path; and
the first objective part comprises the lens, the first stop and the second stop.
29. The projection objective of claim 28 , further comprising a shield configured to reduce direct light leakage from the first objective part into the third objective part.
30. The projection objective of claim 17 , further comprising a mirror.