Arrangement for the thermal actuation of a mirror, in particular in a microlithographic projection exposure apparatus

Patent metadata

Field	Value
Publication number	US-9798254-B2
Application number	US-201514848593-A
Country	US
Kind code	B2
Filing date	Sep 9, 2015
Priority date	Mar 14, 2013
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

The disclosure provides an arrangement for the thermal actuation of a mirror, in particular in a microlithographic projection exposure apparatus, as well as related methods and systems.

First claim

The invention claimed is:

1. An arrangement, comprising:
a mirror comprising a mirror substrate, a first surface which is an optically effective surface, a second surface which is different from the first surface, and an access channel which extends from the second surface toward the first surface;
a cooling element which variably protrudes into the access channel; and
a heat source configured to variably couple heating power into a region of the mirror substrate that adjoins the first surface,
wherein the arrangement is configured so that, during use of the arrangement:
the cooling element does not contact the heat source;
a cooling power of the cooling element and a heating power of the heat source are set to achieve a thermal flux between the first and second surfaces; and
the thermal flux results in a temperature gradient and a related local variation of a value of a coefficient of thermal expansion in the mirror substrate.

2. The arrangement of claim 1 , wherein the mirror comprises a plurality of access channels, and each access channel extends from the second surface toward the first surface.

3. The arrangement of claim 2 , further comprising a plurality of cooling elements, wherein each cooling element variably protrudes into a corresponding access channel.

4. The arrangement of claim 3 , wherein the arrangement is configured so that a cooling power of each cooling elements is independently settable.

5. The arrangement of claim 2 , wherein the heat source comprises a plurality of heat emitters, and each access channel has a corresponding heat emitter.

6. The arrangement of claim 5 , wherein the arrangement is configured so that a heating power of each heat emitter is independently settable.

7. The arrangement of claim 1 , wherein the heat emitter is arranged at an end portion of the access channel which faces the first surface.

8. The arrangement of claim 1 , wherein the cooling element is tubular.

9. The arrangement of claim 1 , wherein the heat source comprises a heat emitters configured so that, during use of the arrangement, the heat emitters couple heating radiation into the access channel.

10. The arrangement of claim 9 , wherein the heating radiation has a wavelength of at least 2.5 μm.

11. The arrangement of claim 1 , wherein:
the mirror comprises a reflective coating;
the heat source comprises a member selected from the group consisting of a heating wire and a heat-dissipating conductor track; and
the member is between the substrate and the reflective coating.

12. The arrangement of claim 1 , wherein the second surface is opposite the first surface.

13. The arrangement of claim 1 wherein:
the mirror comprises a first mirror substrate region comprising a first mirror substrate material;
the mirror comprises a second mirror substrate region comprising a second mirror substrate material;
the second mirror substrate material is different from the first mirror substrate material;
the first mirror substrate region is a first distance from the first surface;
the second mirror substrate region is a second distance from the first surface; and
the second distance is greater than the first distance.

14. The arrangement of claim 13 , wherein, at a temperature, an absolute value of a coefficient of linear expansion of the first mirror substrate material is less than an absolute value of a coefficient of linear expansion of the second mirror substrate material.

15. The arrangement of claim 13 , wherein the first mirror substrate material comprises an ultra-low expansion material.

16. The arrangement of claim 13 , wherein the second mirror substrate material comprises quartz.

17. The arrangement of claim 1 , wherein the arrangement is configured so that, during use of the arrangement, a deformation profile of the mirror is producible by varying at least one member selected from the group consisting of the heating power of the heat source and the cooling power of the cooling element.

18. The arrangement of claim 1 , wherein the arrangement is configured so that, during use of the arrangement, varying a temperature variation in a region of the substrate facing away from the first surface deforms the region of the substrate facing away from the first, and the deformation is mechanically transferred to the first surface.

19. The arrangement of claim 1 , wherein the mirror comprises a reflective material and an absorbent layer, the absorbent layer is configured to absorb heating radiation coupled into the access channel, and the absorbent layer is between the substrate and the reflective material.

20. An apparatus, comprising:
an arrangement according to claim 1 ,
wherein the apparatus is a microlithographic projection exposure apparatus.

21. A method of thermally actuating a mirror of a microlithographic projection exposure apparatus, the mirror comprising a substrate, a first surface which is an optically effective surface, a second surface which is different from the first surface, an access channel extending from the second surface toward the first surface, the method comprising:
coupling heating power into a region of the substrate using a heat source;
defining a deformation profile of the mirror by varying the heating power to substrate and/or varying the cooling power of a cooling element protruding into the access channel so that a temperature of the mirror in a region of the first surface is kept constant to within ±3 K,
wherein the cooling element does not contact the heat source.

22. The method of claim 21 , wherein the constant value corresponds to the zero-crossing temperature of the mirror substrate material in the region concerned.

23. The method of claim 21 , wherein the temperature of the mirror is in the range of 22° C. to 55° C.

24. The method of claim 21 , wherein varying the heating power of the heat source comprises at least partially compensating a heat input into the first surface caused by optical loads during use of the projection exposure apparatus.

25. The method of claim 21 , comprising setting the cooling power of the cooling element and the heating power to achieve a thermal flux between the first and second surfaces, wherein the thermal flux results in a temperature gradient and a related local variation of a value of the coefficient of thermal expansion in the substrate.

26. The method of claim 25 , wherein the local variation is such that the coefficient of thermal expansion in the substrate increases in a direction from the first surface to the second surface.

27. The method of claim 21 , comprising varying a temperature in a region of the substrate facing away from the first surface to deform the region of the substrate facing away from the first surface, wherein the deformation is mechanically transferred to the first surface.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Hauf Markus

Classifications

• G03F7/70891 Primary

  Temperature · CPC title

• G02B26/0825

  the reflecting element being a flexible sheet or membrane, e.g. for varying the focus (flexible mirrors for cosmetic use A45D42/24) · CPC title

• G03F7/70883

  of optical 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

• G02B7/181

  with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation · CPC title