Imaging optical unit
AssigneeCarl Zeiss SMT GmbH
InventorsHans-Jürgen Rostalski, Holger Münz, Christoph Menke
Life of this patent
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Abstract
An imaging optical unit comprises a plurality of mirrors for imaging an object field in an object plane into an image field in an image plane. An image-side numerical aperture is greater than 0.55. A ratio between an object/image offset and a meridional transverse direction is at least 0.5. A ratio between a working distance between the object plane and a reflection portion, closest to the object plane, of one of the mirrors and the meridional transverse dimension is at least 0.05. The working distance is at least 270 mm. This can yield an imaging optical unit, the use of which is relatively manageable in a projection exposure apparatus, such as for EUV projection lithography.
Claims20
An imaging optical unit, comprising:
- a plurality of mirrors configured to image an object field in an object plane into an image field in an image plane, wherein:
- the imaging optical unit has an image-side numerical aperture greater than 0.55;
- the imaging optical unit has an object/image offset between a separation plane and a center of the image field;
- a center of the object field is located in the separation plane;
- the separation plane is perpendicular to a meridional plane of the imaging optical unit;
- the imaging optical unit has a working distance between the object plane and a reflection portion, closest to the object plane, of one of the mirrors;
- the working distance is at least 270 mm;
- the imaging optical unit has a meridional transverse dimension between the separation plane and a reflection portion, furthest from the separation plane, of one of the mirrors;
- a ratio of the object/image offset to the meridional transverse dimension is 0.76;
- and
- a ratio of the working distance to the meridional transverse dimension is at least 0.05.
Dependencies are inferred from the claim text.