Projection lens, projection exposure apparatus and projection exposure method for EUV microlithography

Patent metadata

Field	Value
Publication number	US-10048592-B2
Application number	US-201715441441-A
Country	US
Kind code	B2
Filing date	Feb 24, 2017
Priority date	Sep 15, 2014
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A projection lens is disclosed for imaging a pattern arranged in an object plane of the projection lens into an image plane of the projection lens via electromagnetic radiation having an operating wavelength λ from the extreme ultraviolet range. The projection lens includes a multiplicity of mirrors having mirror surfaces arranged in a projection beam path between the object plane and the image plane so that a pattern of a mask in the object plane is imagable into the image plane via the mirrors. A first imaging scale in a first direction running parallel to a scan direction is smaller in terms of absolute value than a second imaging scale in a second direction perpendicular to the first direction. The projection lens also includes a dynamic wavefront manipulation system for correcting astigmatic wavefront aberration portions caused by reticle displacement.

First claim

What is claimed is:

1. A projection lens configured to image a pattern of a reticle in an object plane of the projection lens into an image plane of the projection lens via radiation having an EUV operating wavelength, the projection lens comprising:
a multiplicity of mirrors, each mirror having a surface in a projection beam path between the object plane and the image plane so that the pattern of the reticle in the object plane is imagable into the image plane via the mirrors; and
a dynamic wavefront manipulation system configured to correct astigmatic wavefront aberration portions caused by reticle displacement in a direction perpendicular to the object plane,
wherein:
a first imaging scale in a first direction parallel to a scan direction is smaller in terms of absolute value than a second imaging scale in a second direction perpendicular to the first direction;
the wavefront manipulation system is configured so that astigmatic wavefront aberration portions caused by reticle displacement are correctable during a scan operation;
the wavefront manipulation system comprises a first manipulator and a first actuating device;
the plurality of mirrors comprises a displaceable mirror; and
the first actuating device is configured to reversibly change a position of the displaceable mirror relative to a reference position.

2. The projection lens of claim 1 , wherein reversible changing the position of the displaceable mirror comprises at least one displacement selected from the group consisting of:
an axial displacement of the displaceable mirror parallel to a reference axis directed orthogonally to the object plane;
a lateral displacement of the displaceable mirror in a lateral direction perpendicular to a reference axis directed orthogonally to the object plane;
a tilting of the displaceable mirror; and
a rotation about a rotation axis of a reflective freeform surface of the displaceable mirror.

3. The projection lens of claim 2 , wherein the first manipulator is configured so that, during use of the projection lens, the position of the displaceable mirror is changed in a time interval between the beginning and end of a scan operation running in one direction according to a predefinable movement profile from a starting position via at least one intermediate position back to the starting position.

4. The projection lens of claim 3 , wherein the first manipulator is configured so that, during use of the projection lens, the position of the displaceable mirror is changed in less than one second.

5. The projection lens of claim 4 , each of the plurality of mirrors has an actuating device configured to reversibly change a position of the mirror in relation to a reference position to correct astigmatic wavefront aberration portions caused by reticle displacement in direction perpendicular to the object plane.

6. The projection lens of claim 5 , wherein:
the wavefront manipulation system comprises a second manipulator and a second actuating device;
the plurality of mirrors comprises a deformable mirror; and
the second actuating device is configured to reversibly astigmatically change a shape of the surface of the deformable mirror relative to a reference surface shape.

7. The projection lens of claim 6 , wherein:
the projection lens has a pupil surface between the object plane and the image plane;
the deformable mirror is arranged optically in proximity to the pupil surface so that the astigmatically changeable mirror surface of the deformable mirror is arranged at a subaperture ratio that is between 0.5 and 1.

8. The projection lens of claim 7 , wherein the first and second manipulators are configured so that an actuating movement relevant to the change of the optical effect of the mirror is generatable within less than one second.

9. The projection lens of claim 8 , wherein a ratio of the second imaging to the first imaging scale is in the range of 1.1 to 2.5.

10. The projection lens of claim 1 , wherein a front focal length of the projection lens in the second direction has an absolute value of less than three meters.

11. The projection lens of claim 10 , wherein the projection lens is configured to image a ring field that is curved in the scan direction.

12. The projection lens of claim 11 , wherein a curvature of the ring field is configured so that in the image plane a distance measured in the scan direction between a middle field point at a field edge lagging in the scan direction and marginal field points at the margin of the field edge is more than 5% of the field width measured perpendicular to the scan direction.

13. An apparatus, comprising:
an illumination system; and
a projection lens according to claim 1 ,
wherein the illumination system is configured to illuminate a reticle in the object field of the projection lens, and the apparatus is a projection exposure apparatus.

14. The apparatus of claim 13 , further comprising a reticle holding device comprising a displacement device to control displacement of the reticle parallel to a direction running orthogonally to the object plane.

15. The apparatus of claim 14 , wherein the displacement device is configured to displace the reticle in a time interval between beginning and end of a scan operation running in one direction according to a predefinable movement profile.

16. A method of using a projection exposure apparatus comprising an illumination optical assembly and a projection optical assembly, the method comprising:
using the illumination optical assembly to illuminate at least one section of a reticle with radiation; and
using the projection optical assembly to project an image of the at least one section of the reticle onto a material that is sensitive to the radiation,
wherein the projection lens is a projection lens according to claim 1 .

17. A method, comprising:
providing a reticle between an illumination system and an anamorphic projection lens of a projection exposure apparatus so that a pattern of the reticle is in a region of an object plane of the projection lens and is imagable via the projection lens into an image plane of the projection lens, the image plane being optically conjugate tospect to the object plane;
illuminating an illumination region of the pattern of the reticle with an illumination radiation provided by the illumination system;
moving the reticle in a scan direction during a scan operation;
displacing the reticle in a displacement direction perpendicular to the object plane; and
correcting astigmatic wavefront aberration portions caused by the displacement of the reticle via a dynamic wavefront manipulation system.

18. The method of claim 17 , wherein displacing the reticle and correcting astigmatic wavefront aberration portions are performed during the scan operation.

19. A method, comprising:
providing a reticle between an illumination system and an anamorphic projection lens of a projection exposure apparatus so that a pattern of the reticle is in a region of the object plane of the projection lens;
positioning a substrate so that a radiation-sensitive surface of the substrate is in a region of an image plane of the projection lens, the image plane being optically conjugate to the object plane;
illuminating an illumination region of the reticle with an illumination radiation provided by the illumination system;
projecting a part of the pattern that lies in the illumination region onto an image field at the substrate with the aid of the projection lens;
moving the reticle in a scan direction during a scan oper

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Andre Stephan
• Golde Daniel
• Gruner Toralf
• Ruoff Johannes
• Wabra Norbert
• Schoemer Ricarda
• Schneider Sonja

Classifications

• G03F7/70233 Primary

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

• G03F7/7015

  Details of optical elements · CPC title

• G03F7/70258

  Projection system adjustments, e.g. adjustments during exposure or alignment during assembly of projection system · CPC title

• G03F7/70266 Primary

  Adaptive optics, e.g. deformable optical elements for wavefront control, e.g. for aberration adjustment or correction · CPC title

• G03F7/70033

  by plasma extreme ultraviolet [EUV] sources · CPC title