US 9,810,992 B2
Illumination system
Markus Deguenther, Aalen (DE)
Assigned to Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed by Carl Zeiss SMT GmbH, Oberkochen (DE)
Filed on Mar. 10, 2016, as Appl. No. 15/66,039.
Application 15/066,039 is a continuation of application No. PCT/EP2014/067962, filed on Aug. 25, 2014.
Claims priority of application No. 10 2013 218 128 (DE), filed on Sep. 11, 2013.
Prior Publication US 2016/0187785 A1, Jun. 30, 2016
Int. Cl. G03F 7/20 (2006.01)
CPC G03F 7/702 (2013.01) [G03F 7/70075 (2013.01); G03F 7/70175 (2013.01)] 21 Claims
OG exemplary drawing
 
1. An illumination system, comprising:
a collector; and
illumination optics, comprising:
a field facet mirror comprising a multiplicity of field facets; and
a pupil facet mirror comprising a multiplicity of pupil facets,
wherein:
the collector is configured to transfer EUV illumination light from a radiation source region to the illumination optics;
the illumination optics are configured to guide the EUV illumination light collected by the collector;
the multiplicity of pupil facets comprise part of pupil facet transfer optics configured to image the field facets in a manner superposed on one another into the object field;
the collector comprises collector imaging optics configured to image the radiation source region into a focal region downstream of the collector imaging optics;
the illumination system is configured so that, during use of the illumination system, a first image of the radiation source region in a beam path of the EUV illumination light after the radiation source region is in the focal region;
a constriction region lies between the collector and a first component of the illumination optics;
the constriction region does not coincide with the focal region;
a cross section of an overall beam of the EUV illumination light has a minimum cross section;
the minimum cross section of the overall beam of the EUV illumination light is in the constriction region; and
in the constriction region, the cross section of the overall beam of the EUV illumination light is reduced by at least a factor of two compared to a cross section on the field facet mirror.