Illumination optical unit for EUV projection lithography

Patent metadata

Field	Value
Publication number	US-9612537-B2
Application number	US-201615002823-A
Country	US
Kind code	B2
Filing date	Jan 21, 2016
Priority date	Mar 19, 2012
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

An EUV projection lithography illumination optical unit guides illumination light toward an object field, the illumination optical unit comprising. The unit includes: a first facet mirror comprising a plurality of first monolithic facets; and a second facet mirror downstream of the first facet mirror in a beam path of the illumination light, the second facet mirror comprising a plurality of second facets, each second facet being configured to contribute to imaging a corresponding first monolithic facet of the first facet mirror into the object field via an illumination channel. Individual parts of the first monolithic facets are configured so that illumination light is guided from the individual parts of the first monolithic facets toward different target locations on the corresponding second facet of the second facet mirror.

First claim

The invention claimed is:

1. An illumination optical unit configured to guide illumination light toward an object field, the illumination optical unit comprising:
a first facet mirror comprising a plurality of first monolithic facets; and
a second facet mirror downstream of the first facet mirror in a beam path of the illumination light, the second facet mirror comprising a plurality of second facets, each second facet being configured to contribute to imaging a corresponding first monolithic facet of the first facet mirror into the object field via an illumination channel,
wherein:
individual parts of the first monolithic facets are configured so that illumination light is guided from the individual parts of the first monolithic facets toward different target locations on the corresponding second facet of the second facet mirror; and
the illumination optical unit is an EUV projection lithography illumination optical unit.

2. The illumination optical unit of claim 1 , wherein the individual parts of the first monolithic facets are configured so that the different target locations on the corresponding facet of the second facet mirror are arranged along a target location path running over the facet.

3. The illumination optical unit of claim 2 , wherein the individual parts of the first monolithic facets are configured so that the target location path runs rectilinearly.

4. The illumination optical unit of claim 3 , wherein reflection surfaces of the facets of the second facet mirror have a larger extent along a target location path than perpendicularly thereto.

5. The illumination optical unit of claim 4 , wherein the second facet mirror comprises having extents that differ in terms of their extent along the target location path.

6. The illumination optical unit of claim 2 , wherein reflection surfaces of the facets of the second facet mirror have a larger extent along a target location path than perpendicularly thereto.

7. The illumination optical unit of claim 6 , wherein the second facet mirror comprises having extents that differ in terms of their extent along the target location path.

8. The illumination optical unit of claim 1 , wherein reflection surfaces of the facets of the second facet mirror have a larger extent along a target location path than perpendicularly thereto.

9. The illumination optical unit of claim 8 , wherein the second facet mirror comprises having extents that differ in terms of their extent along the target location path.

10. The illumination optical unit of claim 1 , wherein the second facet mirror comprises having extents that differ in terms of their extent along the target location path.

11. The illumination optical unit of claim 1 , wherein:
the object field is spanned by two object field coordinates; and
the individual mirrors of an individual mirror group which belong to the same coordinate value of one of the two object field coordinates are configured to guide the individual mirror illumination channels of the individual mirrors toward the same target location on the corresponding facet of the second facet mirror.

12. An illumination system, comprising:
an illumination optical unit configured to guide illumination light toward an object field, the illumination optical unit comprising:
a first facet mirror comprising a plurality of first monolithic facets; and
a second facet mirror downstream of the first facet mirror in a beam path of the illumination light, the second facet mirror comprising a plurality of second facets, each second facet being configured to contribute to imaging a corresponding first monolithic facet of the first facet mirror into the object field via an illumination channel; and

a projection optical unit configured to image the object field into an image field,
wherein:
individual parts of the first monolithic facets are configured so that illumination light is guided from the individual parts of the first monolithic facets toward different target locations on the corresponding second facet of the second facet mirror; and
the illumination system is an EUV illumination system.

13. The illumination system of claim 12 , wherein the individual parts of the first monolithic facets are configured so that the different target locations on the corresponding facet of the second facet mirror are arranged along a target location path running over the facet.

14. The illumination system of claim 13 , wherein the individual parts of the first monolithic facets are configured so that the target location path runs rectilinearly.

15. An apparatus, comprising:
an EUV light source;
an illumination optical unit configured to guide illumination light toward an object field, the illumination optical unit comprising:
a first facet mirror comprising a plurality of first monolithic facets; and
a second facet mirror downstream of the first facet mirror in a beam path of the illumination light, the second facet mirror comprising a plurality of second facets, each second facet being configured to contribute to imaging a corresponding first monolithic facet of the first facet mirror into the object field via an illumination channel; and

a projection optical unit configured to image the object field into an image field,
wherein:
individual parts of the first monolithic facets are configured so that illumination light is guided from the individual parts of the first monolithic facets toward different target locations on the corresponding second facet of the second facet mirror; and
the apparatus is a projection exposure apparatus.

16. The apparatus of claim 15 , wherein a target location path runs parallel to a displacement direction.

17. The apparatus of claim 15 , wherein the individual parts of the first monolithic facets are configured so that the different target locations on the corresponding facet of the second facet mirror are arranged along a target location path running over the facet.

18. The apparatus of claim 17 , wherein the individual parts of the first monolithic facets are configured so that the target location path runs rectilinearly.

19. A method of operating a projection exposure apparatus comprising an illumination optical unit and a projection optical unit, the method comprising:
using the illumination optical unit to illuminate at least some structures of a reticle; and
using the projection optical unit to image at least some of the illuminated structure onto a light-sensitive material,
wherein the projection optical unit comprises an illumination unit according to claim 1 .

20. The method of claim 19 , wherein the individual parts of the first monolithic facets are configured so that the different target locations on the corresponding facet of the second facet mirror are arranged along a target location path running over the facet.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Patra Michael

Classifications

• G03F7/702 Primary

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

• G02B26/0833 Primary

  the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B) · 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

• G03F7/70083

  Non-homogeneous intensity distribution in the mask plane · CPC title

• G03F7/70075

  Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection · CPC title