Projection objective for microlithography

摘要

A projection objective for microlithography is used for imaging an object field in an object plane into an image field in an image plane. The projection objective comprises at least six mirrors of which at least one mirror has a freeform reflecting surface. The ratio between an overall length (T) of the projection objective and an object image shift (dOIS) can be smaller than 12. The image plane is the first field plane of the projection objective downstream of the object plane. The projection objective can have a plurality of mirrors, wherein the ratio between an overall length (T) and an object image shift (dOIS) is smaller than 2.

主权项

1. An optical system, comprising:
an illumination optics, comprising:
a collector; andonly two mirrors configured to guide light from the collector to illuminate an object field in an object plane; and a projection objective configured to image the object field into an image field in an image plane, wherein:
the optical system is a microlithography optical system;the illumination optics is configured so that the light has an intermediate focus between a light source that generates the light and the object field;the intermediate focus is between the object plane and the image plane;a ratio of an overall length of the projection objective to an intermediate-focus image shift is less than 2;an object image shift of the projection objective is greater than 200 mm.