Imaging optical system and projection exposure installation for microlithography with an imaging optical system of this type

Patent metadata

Field	Value
Publication number	US-9500958-B2
Application number	US-201314085614-A
Country	US
Kind code	B2
Filing date	Nov 20, 2013
Priority date	Feb 12, 2009
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

An imaging optical system has a plurality of mirrors, which via a beam path for imaging light, image an object field in an object plane into an image field in an image plane. The imaging optical system has an exit pupil obscuration. At least one of the mirrors has no opening for passage of the imaging light. The fourth to last mirror in the beam path is concave, resulting in an imaging optical system having improved imaging properties without compromise in throughput.

First claim

What is claimed is:

1. An imaging optical system, comprising:
a plurality of mirrors configured to image an object field in an object plane into an image field in an image plane along a beam path of imaging light,
wherein:
the image field has an area spanned by a first dimension and a second dimension which is perpendicular to the first dimension;
the second dimension is larger than the first dimension;
the first dimension is at least 2 mm;
the imaging optical system has a demagnification ratio of 8×; and
the imaging optical system is a catoptric imaging optical system.

2. The imaging optical system of claim 1 , wherein the image field has an arc shape.

3. The imaging optical system of claim 1 , wherein the image field is rectangular.

4. The imaging optical system of claim 1 , wherein the first dimension is 2 mm, and the second dimension is 26 mm.

5. The imaging optical system of claim 4 , wherein the image field has an arc shape.

6. The imaging optical system of claim 4 , wherein the image field is rectangular.

7. The imaging optical system of claim 1 , wherein:
the plurality of mirrors comprises a second to last mirror in the beam path between the object field and the image field;
the plurality of mirrors comprises a third to last mirror in the beam path between the object field and the image field;
the plurality of mirrors comprises a fourth to last mirror in the beam path between the object field and the image field; and
the beam path between the third to last mirror and the second to last mirror passes the fourth to last mirror at a distance to a normal of a center of the image field that is smaller than a distance of the fourth to last mirror to the normal to the image field.

8. The imaging optical system of claim 1 , wherein the imaging optical system has an intermediate image plane in the beam path between the object plane and the image plane.

9. The imaging optical system of claim 8 , wherein the intermediate image is located a spatial distance from the last mirror that is more than 10% of a spatial distance between the object plane and the image plane.

10. The imaging optical system of claim 8 , wherein:
the plurality of mirrors comprises a third to last mirror in the beam path between the object field and the image field; and
the intermediate image is located in the beam path in front of the third to last mirror.

11. The imaging optical system of claim 1 , wherein the imaging optical system has an intermediate pupil plane in the beam path between the object plane and the image plane, and the intermediate pupil plane is in the vicinity of one of the plurality of mirrors.

12. The imaging optical system of claim 1 , wherein the imaging optical system has an image side numerical aperture of at least 0.4.

13. The imaging optical system of claim 1 , wherein the plurality of mirrors comprises a fourth to last mirror in the beam path between the object field and the image field, and a maximum angle of incidence for a chief ray of the imaging light at a central object point on the fourth to last mirror is at most 10°.

14. The imaging optical system of claim 1 , wherein the plurality of mirrors comprises a fourth to last mirror in the beam path between the object field and the image field, a maximum angle of incidence for the imaging light on the fourth to last mirror in a meridional plane of the imaging optical system is at most 10°.

15. The imaging optical system of claim 1 , wherein the imaging optical system has a maximum wave front error of 47 mλ.

16. The imaging optical system of claim 1 , wherein the imaging optical system has a maximum distortion of 35 nm.

17. The imaging optical system of claim 1 , wherein the imaging optical system is a microlithography projection optical system.

18. The imaging optical system of claim 1 , wherein the projection exposure installation is configured to operate at a wavelength of between 5 nm and 30 nm.

19. A projection exposure installation, comprising:
an imaging optical system comprising a plurality of mirrors configured to image an object field in an object plane into an image field in an image plane along a beam path of imaging light; and
an illumination optical system configured to guide illumination light to the object field of the imaging optical system,
wherein:
the image field of the imaging optical system has an area spanned by a first dimension and a second dimension which is perpendicular to the first dimension;
the second dimension is larger than the first dimension;
the first dimension is at least 2 mm;
the imaging optical system has a demagnification ratio of 8×;
the projection exposure installation is a microlithography projection exposure installation; and
the imaging optical system is a catoptric imaging optical system.

20. The projection exposure installation of claim 18 , wherein the projection exposure installation is configured to operate at a wavelength of between 5 nm and 30 nm.

21. A method, comprising:
providing a microlithography projection exposure installation, comprising:
an imaging optical system comprising a plurality of mirrors configured to image an object field in an object plane into an image field in an image plane along a beam path of imaging light; and
an illumination optical system configured to guide illumination light to the object field of the imaging optical system; and

using the projection exposure installation to project a structure of a reticle onto a light-sensitive layer of a wafer,
wherein:
the image field of the imaging optical system has an area spanned by a first dimension and a second dimension which is perpendicular to the first dimension;
the second dimension is larger than the first dimension;
the first dimension is at least 2 mm;
the imaging optical system has a demagnification ratio of 8×; and
the imaging optical system is a catoptric imaging optical system.

22. The method of claim 21 , wherein the imaging light has a wavelength of between 5 nm and 30 nm.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Mann Hans-Juergen
• Shafer David

Classifications

• G02B17/0663 Primary

  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 title

• G03F7/70233 Primary

  Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems · CPC title

• G02B17/0652

  on-axis systems with at least one of the mirrors having a central aperture · CPC title

• G03F7/7015

  Details of optical elements · CPC title

• G02B17/0647

  using more than three curved mirrors (G02B17/0668, G02B17/0694 take precedence) · CPC title