Catadioptric projection objective comprising deflection mirrors and projection exposure method

Patent metadata

Field	Value
Publication number	US-9459435-B2
Application number	US-201615005286-A
Country	US
Kind code	B2
Filing date	Jan 25, 2016
Priority date	Sep 29, 2009
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

A catadioptric projection objective has a multiplicity of lenses and at least one concave mirror, and also two deflection mirrors in order to separate a partial beam path running from the object field to the concave mirror from the partial beam path running from the concave mirror to the image field. The deflection mirrors are tilted relative to the optical axis of the projection objective about tilting axes running parallel to a first direction (x-direction). The first deflection mirror is arranged in optical proximity to a first field plane and the second deflection mirror is arranged in optical proximity to a second field plane, which is optically conjugate with respect to the first field plane. A displacement device for the synchronous displacement of the deflection mirrors is provided. The deflection mirrors have different local distributions of their reflection properties in first and second reflection regions, respectively.

First claim

The invention claimed is:

1. A projection objective configured to image an object field into an image field, the projection objective comprising:
a multiplicity of lenses;
a concave mirror;
a first deflection mirror configured to deflect radiation from the object field to the concave mirror;
a second deflection mirror configured to deflect radiation from the concave mirror to the image field,
wherein:
the projection objective has an optical axis;
relative to the optical axis of the projection objective, the first deflection mirror is tilted about an axis perpendicular to the optical axis and parallel to a first direction;
relative to the optical axis of the projection objective, the second deflection mirror is tilted about an axis perpendicular to the optical axis and parallel to the first direction;
the first deflection mirror is displaceable parallel to the first direction; and
the second deflection mirror is displaceable parallel to the first direction.

2. The projection objective of claim 1 , wherein the projection objective has an imaging scale between 0.8 and 1.2.

3. The projection objective of claim 1 , wherein during use of the projection objective:
the first deflection mirror has a first position and a second position that is different from the first position;
radiation passes from the object field to the image field to image the object field into the image field;
when the first deflection mirror is in its first position, the radiation impinges on a first reflection region of the first deflection mirror;
when the first deflection mirror is in its second position, the radiation impinges on a second reflection region of the first deflection mirror; and
the second reflection region of the first deflection mirror is offset from the first reflection region of the first deflection mirror in a direction parallel the first direction.

4. The projection objective of claim 3 , wherein a distribution of reflectivity of the first reflection region of the first deflection mirror is different from a distribution of reflectivity of the second reflection region of the first deflection mirror.

5. The projection objective of claim 3 , wherein a reflection coating of the first deflection mirror has a thickness that changes linearly in a direction parallel to the first direction.

6. The projection objective of claim 3 , wherein a reflectivity of the first reflection region of the first deflection mirror is constant, and a thickness of a reflection coating of the first deflection mirror is non-constant in the second reflection region of the first deflection mirror.

7. The projection objective of claim 3 , wherein during use of the projection objective:
the second deflection mirror has a first position and a second position that is different from the first position;
when the second deflection mirror is in its first position, the radiation impinges on a first reflection region of the second deflection mirror;
when the second deflection mirror is in its second position, the radiation impinges on a second reflection region of the second deflection mirror; and
the second reflection region of the second deflection mirror is offset from the first reflection region of the second deflection mirror in a direction parallel to the first direction.

8. The projection objective of claim 1 , wherein:
the first deflection mirror has a non-planar mirror surface having a surface form in a direction parallel to the first direction;
the second deflection mirror has a non-planar mirror surface having a surface form in a direction parallel to the first direction; and
the surface form of the second deflection mirror is opposite to the surface form of the first direction in a direction parallel to the first direction.

9. The projection objective of claim 8 , wherein the surface form of the first deflection mirror deviates from a planar surface by less than 10 μm, and the surface form of the second deflection mirror deviates from a planar surface by less than 10 μm.

10. The projection objective of claim 1 , wherein:
a mirror surface of the first deflection mirror has a profile in a direction parallel to the first direction; and
the profile of the mirror surface of the first deflection mirror is selected from the group consisting of a parabolic surface profile, a cubic surface profile, a surface profile following a polynomial, and a profile with a positive curvature of the mirror surface in a first surface portion and a negative curvature in a second surface portion offset from the first surface portion.

11. The projection objective of claim 10 , wherein:
a mirror surface of the second deflection mirror has a profile in a direction parallel to the first direction; and
the profile of the mirror surface of the second deflection mirror is selected from the group consisting of a parabolic surface profile, a cubic surface profile, a surface profile following a polynomial, and a profile with a positive curvature of the mirror surface in a first surface portion and a negative curvature in a second surface portion offset from the first surface portion.

12. The projection objective of claim 1 , wherein a mirror surface of the first deflection mirror is disposed at a location within the projection objective having a subaperture ratio of less than 0.3, and a mirror surface of the second deflection mirror is disposed at a location within the projection objective having a subaperture ratio of less than 0.3.

13. The projection objective of claim 1 , further comprising a device configured to displace the first and second deflection mirrors parallel to the first direction.

14. The projection objective of claim 13 , wherein the device comprises a drive to synchronously displace the first and second deflection mirrors parallel to the first direction, and the drive is actuable during use the projection objective.

15. The projection objective of claim 1 , wherein the first and second deflection mirrors are synchronously displaceable parallel to the first direction.

16. The projection objective of claim 1 , further comprising a carrier structure that supports both the first and second deflection mirrors.

17. The projection objective of claim 1 , wherein the projection objective comprises a prism, and the first and second deflection surfaces define perpendicularly oriented surfaces of the prism.

18. The projection objective of claim 1 , wherein the projection objective comprises:
a first objective part configured to image the object plane into a first intermediate image;
a second objective part configured to image the first intermediate image into a second intermediate image; and
a third objective part configured to image the second intermediate image into the image surface, and
wherein:
the concave mirror is in a region of a pupil surface between the first and the second intermediate images;
the first deflection mirror is in optical proximity to the first intermediate image; and
the second deflection mirror is in optical proximity to the second intermediate image.

19. The projection objective of claim 1 , wherein the projection objective comprises:
a first objective part configured to image the object plane into an intermediate image; and
a second objective part configured to image the intermediate image into the image surface, and
wherein:
the concave mirror is in a region of a pupil surface between the object field and the intermediate image;
the first deflection mirror is in optical proximity to the object field; and
the second deflectio

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Schicketanz Thomas
• Gruner Toralf

Classifications

• G02B17/0892 Primary

  specially adapted for the UV · CPC title

• G02B17/08 Primary

  Catadioptric systems {(used in non-imaging applications G02B19/00)} · CPC title

• G03F7/70225

  Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements · CPC title

• G03F7/702

  Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems · CPC title

• G02B13/14

  for use with infrared or ultraviolet radiation ({G02B13/008, } G02B13/16 take precedence) · CPC title