EUV COLLECTOR

• US 20120050703A1
• Filed: 08/22/2011
• Published: 03/01/2012
• Est. Priority Date: 08/31/2010
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Inventors: Layh, Michael, Dinger, Udo
• Granted Patent: US 9,007,559 B2
• Time in Patent Office: Days
• US Class Current: 355/30
• CPC Class Codes: G03F 7/70175 Lamphouse reflector arrangements or collector mirrors, i.e. collecting light from solid angle upstream of the light source
• CPC Class Codes: G03F 7/70891 Temperature
• CPC Class Codes: G21K 1/06 using diffraction, refraction or reflection, e.g. monochromators G21K1/10, G21K7/00 take precedence
• CPC Class Codes: G21K 2201/065 provided with cooling means
• CPC Class Codes: G21K 2201/067 Construction details

Abstract

An EUV collector for collecting and transmitting radiation from an EUV radiation source includes at least one collector mirror for reflecting an emission of the EUV radiation source, which is rotationally symmetric with respect to a central axis. The EUV collector also includes a cooling device for cooling the at least one collector mirror. The cooling device has at least one cooling element, which has a course with respect to the collector mirror, in each case, such that the projection of the course into a plane perpendicular to the central axis has a main direction, which encloses an angle of at most 20° with respect to a predetermined preferred direction. The collector transmits improved quality radiation to illuminate an object field.

Claims

1. An EUV collector configured to collect and transmit EUV radiation, the EUV collector comprising:

a collector mirror configured to reflect the EUV radiation, the collector mirror being rotationally symmetric with respect to a central axis; and

a cooling device configured to cool the collector mirror, the cooling device comprising a cooling element having a course with respect to the collector mirror such that a projection of the course into a plane perpendicular to the central axis has a main direction enclosing an angle of at most 20°

with respect to a predetermined preferred direction.

2. The EUV collector of claim 1, wherein the angle is at most 7°

with respect to the predetermined preferred direction.

3. The EUV collector of claim 1, wherein the projection of the course of the cooling element is parallel to the predetermined preferred direction.

4. The EUV collector of claim 1, wherein the cooling device comprises at least two spatially separate cooling elements.

5. The EUV collector of claim 4, wherein, for two of the spatially separate cooling elements, the projection of the course of each cooling element into the plane perpendicular to the central axis is at least approximately parallel to the projection of the course of the other cooling element into the plane perpendicular.

6. The EUV collector of claim 4, wherein, in at least some portions, the projection of the course of each of the at least two cooling elements into the plane perpendicular to the central axis is parallel to the projection of the course of the other cooling elements into the plane perpendicular to the central axis.

7. The EUV collector of claim 4, wherein each of the at least two cooling elements is independently controllable.

8. The EUV collector of claim 1, wherein the cooling element is a cooling channel that is loadable with a cooling medium.

9. The EUV collector of claim 1, wherein:

the cooling device comprises a plurality of cooling element;

for each of the plurality of cooling elements, the cooling element has a course with respect to the collector mirror such that a projection of the course into a plane perpendicular to the central axis has a main direction enclosing an angle of at most 20°

with respect to a predetermined preferred direction.

10. The EUV collector of claim 9, wherein, for each of the plurality of cooling elements, the angle is at most 7°

with respect to the predetermined preferred direction.

11. The EUV collector of claim 9, wherein, for each of the plurality of cooling elements, the projection of the course of the cooling element is parallel to the predetermined preferred direction.

12. An illumination system, comprising:

an EUV collector according to claim 1; and

an illumination optical system comprising an imaging optical system, the illumination optical system being configured to illuminate an object field imaged by the imaging optical system with the radiation collected by the collector.

13. The illumination system of claim 12, wherein:

the illumination optical system further comprises a facet mirror comprising a plurality of facets configured to produce a defined illumination setting to illuminate the object field; and

the preferred direction is predetermined by the longitudinal orientation of at least one of the plurality of facets.

14. The illumination system of claim 12, further comprising an EUV radiation source.

15. The illumination system of claim 12, wherein the illumination system is a microlithography illumination system.

16. A projection exposure system, comprising:

an illumination system, comprising;

an EUV collector according to claim 1; and

an illumination optical system comprising an imaging optical system, the illumination optical system being configured to illuminate an object field imaged by the imaging optical system with the radiation collected by the collector; and

an imaging optical system configured to image the object field into an image field.

17. The projection exposure system of claim 16, wherein the projection exposure system is a microlithography projection exposure system.

18. The projection exposure system of claim 16, wherein:

the illumination optical system further comprises a facet mirror comprising a plurality of facets configured to produce a defined illumination setting to illuminate the object field; and

the preferred direction is predetermined by the longitudinal orientation of at least one of the plurality of facets.

19. The projection exposure system of claim 16, further comprising an EUV radiation source.

20. A method, comprising:

providing a projection exposure system, comprising;

an illumination system, comprising;

an EUV collector according to claim 1; and

an illumination optical system comprising an imaging optical system, the illumination optical system being configured to illuminate an object field imaged by the imaging optical system with the radiation collected by the collector; and

an imaging optical system configured to image the object field into an image field;

using the projection exposure system to project a portion of a reticle onto a wafer having a light-sensitive coating; and

developing the exposed light-sensitive coating.