Illumination optical unit for microlithography

Patent metadata

Field	Value
Publication number	US-9235137-B2
Application number	US-201213370829-A
Country	US
Kind code	B2
Filing date	Feb 10, 2012
Priority date	Sep 30, 2009
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

An illumination optical unit includes a collector mirror which produces a polarization distribution that is applied to the first faceted optical element during the operation of the illumination optical unit. There are at least two first facet elements to which radiation having a differing polarization is applied. The first faceted optical element has at least one first state in which the normal vectors of the reflective surfaces of the first facet elements are selected so that a first predetermined polarization distribution results at the location of the object field during the operation of the illumination optical unit.

First claim

What is claimed is:

1. An optical unit configured to illuminate an object field in an object plane, the optical unit comprising:
a collector mirror; and
a first faceted optical element comprising a plurality of facet elements comprising a first facet element and a second facet element,
wherein:
each the plurality of facet elements comprises a reflective surface having a normal vector whose direction spatially defines an orientation of the reflective surface;
the collector mirror is configured so that, during use of the optical unit, the collector mirror produces a polarization distribution so that, a polarization applied to the first facet element is different from a polarization applied to the second facet element;
the first faceted optical element has a first state in which the normal vectors of the reflective surface of each of the plurality of facet elements are configured to produce a polarization distribution at a location of the object field during use of the optical unit; and
the optical unit is an EUV microlithography optical unit.

2. The optical unit of claim 1 , wherein the polarization distribution that is applied to the first faceted optical element during use of the optical unit is different from the polarization distribution results at the location of the object field during use of the optical unit.

3. The optical unit of claim 1 , wherein the polarization distribution at a first location of the object field is different from the polarization distribution at a second location of the object field.

4. The optical unit of claim 1 , wherein the polarization distribution at the location of the object field is a tangential polarization distribution.

5. The optical unit of claim 1 , wherein an angular distribution of incident radiation at the object field has a dipole form at the location of the object field, and each pole a principal polarization direction is perpendicular to a principal dipole axis.

6. The optical unit of claim 1 , further comprising a second faceted optical element comprising a plurality of facet elements configured to superimpose an image of the plurality of facet elements of the first faceted element onto the object field during use of the optical unit.

7. The optical unit of claim 1 , wherein the first facet element is moveable between first and second positions, and a direction of the normal vector of the reflective surface of the first facet element in the first position differs from a direction of the normal vector of the reflective surface of the first facet element in the second position.

8. The optical unit of claim 7 , wherein the polarization distribution at the location of the object field during use of the optical unit is different depending on whether the first facet element is in its first state or its second state.

9. The optical unit of claim 1 , wherein the collector mirror is a double collector.

10. The optical unit of claim 1 , wherein no polarization element is arranged in a beam path between collector mirror and the first faceted optical element.

11. The optical unit of claim 1 , further comprising a polarization element in a beam path between the collector mirror and the first faceted optical element, the polarization element being configured to alter a polarization distribution produced by the collector mirror during use of the optical unit.

12. The optical unit of claim 1 , wherein no polarization element is arranged in a beam path between the first faceted optical element and the object field.

13. An apparatus, comprising:
an optical unit according to claim 1 ,
wherein the apparatus is an EUV microlithography projection exposure apparatus.

14. An optical unit configured to illuminate an object field in an object plane, the optical unit comprising:
a collector mirror;
a first faceted optical element comprising a plurality of facet elements comprising a first facet element and a second facet element; and
a second faceted optical element comprising a plurality of facet elements configured to superimpose an image of the plurality of facet elements of the first faceted optical element onto the object field during use of the optical unit,
wherein:
each facet element of the plurality of facet elements of the first faceted mirror comprises a reflective surface with a normal vector whose direction spatially defines an orientation of the reflective surface;
the collector mirror is configured to produce a polarization distribution so that a polarization applied to the first facet element is different from a polarization applied to the second facet element;
the first faceted optical element has a first state in which the normal vectors of the reflective surface of each of the plurality of facet elements of the first faceted optical element is configured so that a polarization distribution results on the second faceted optical element during use of the optical unit; and
the optical unit is an EUV microlithography optical unit.

15. The optical unit of claim 14 , wherein the polarization distribution on the second faceted optical element is a tangential polarization distribution.

16. The optical unit of claim 15 , wherein a proportion of the radiation in a tangentially directed principal polarization direction increases from a center of the second faceted optical element outward.

17. The optical unit of claim 14 , wherein the first facet element is moveable between first and second positions, and a direction of the normal vector of the reflective surface of the first facet element in the first position differs from a direction of the normal vector of the reflective surface of the first facet element in the second position.

18. The optical unit of claim 17 , wherein the polarization distribution at the location of the object field during use of the optical unit is different depending on whether the first facet element is in its first state or its second state.

19. The optical unit of claim 14 , wherein the collector mirror is a double collector.

20. The optical unit of claim 14 , wherein no polarization element is arranged in a beam path between collector mirror and the first faceted optical element.

21. The optical unit of claim 14 , further comprising a polarization element in a beam path between the collector mirror and the first faceted optical element, the polarization element being configured to alter a polarization distribution produced by the collector mirror during use of the optical unit.

22. The optical unit of claim 14 , wherein no polarization element is arranged in a beam path between the first faceted optical element and the object field.

23. An apparatus, comprising:
an optical unit according to claim 14 ,
wherein the apparatus is an EUV microlithography projection exposure apparatus.

Assignees

• Fiolka Damian
• Stuetzle Ralf
• Zeiss Carl Smt Gmbh

Inventors

• Fiolka Damian
• Stuetzle Ralf

Classifications

• G21K2201/064

  having a curved surface · 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

• G03F7/70233 Primary

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

• G21K2201/06

  using diffractive, refractive or reflecting elements · CPC title

• G21K1/06

  using diffraction, refraction or reflection, e.g. monochromators (G21K1/10, G21K7/00 take precedence) · CPC title