Illumination optic for EUV projection lithography

An illumination optical unit configured to illuminate an object field with illumination light, the illumination optical unit comprising:

• a first facet mirror in a beam path of the illumination light, the first facet mirror comprising a plurality of first facets supported by a first mirror carrier, at least some of the first facets being adjustable between a plurality of tilt positions;
• and
• a second facet mirror downstream of the first facet mirror in the beam path of the illumination light, the second facet mirror comprising a plurality of second facets supported by a second mirror carrier around a facet arrangement center,
• wherein:
• the illumination optical unit is configured so that, during use of the illumination optical unit, partial beams of the illumination light are guided superposed on one another into the object field, respectively via illumination channels;
• one of the first facets and one of the second facets belongs to each of the illumination channels;
• the plurality of second facets comprises maximum angle facets arranged at an edge of the second mirror carrier;
• the maximum angle facets predetermine maximum illumination angles of the illumination light which deviate maximally from a chief ray incidence on the object field;
• the second mirror carrier comprises an illumination light trap portion;
• the illumination light trap portion is a first distance from the facet arrangement center;
• the maximum angle facets are a second distance from the facet arrangement center;
• the first distance is greater than the second distance;
• the illumination light trap portion comprises a reflection surface that is inclined in relation to a carrier plane of the second mirror carrier;
• and
• the reflection surface of the illumination light trap portion is arranged conically around the facet arrangement center.