Projection optical system, exposure apparatus, and exposure method
AssigneeNikon Corporation
InventorYasuhiro OMURA
Life of this patent
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Abstract
A projection objective includes at least four curved mirrors, which include a first curved mirror that is a most optically forward mirror and a second curved mirror that is a second most optically forward mirror, as defined along a light path. In addition, an intermediate lens element is disposed physically between the first and second mirrors, the intermediate lens element being a single pass type lens. The objective forms an image with a numerical aperture of at least substantially 1.0 in immersion.
Claims20
An immersion projection optical system which images a pattern provided in an object surface of the immersion projection optical system onto an image surface of the immersion projection optical system, comprising:
- a first lens unit including at least to lenses;
- a mirror group, arranged between the first lens unit and the image surface, including of two mirrors;
- a second lens unit, arranged between the mirror group and the image surface, including at least one lens;
- a third lens unit, arranged between the second lens unit and the image surface, including at least two negative lenses;
- and
- a fourth lens unit, arranged between the second lens unit and the image surface, including a liquid immersed optical element which is contact with a liquid and a plurality of lenses between the third lens unit and the liquid immersed optical element,
- wherein a maximum diameter of the fourth lens unit larger than a maximum diameter of the third lens unit,
- wherein number of mirrors belonging the immersion projection optical system are two, and
- wherein every transmitting member and every mirror constituting the projection optical system are arranged along a single straight optical axis.
Dependencies are inferred from the claim text.