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AssigneeCarl Zeiss SMT GmbH
InventorsDaniel Krähmer, Toralf Gruner, Wilhelm Ulrich, Birgit Enkisch, Michael Gerhard, Martin Brunotte, Christian Wagner, Winfried Kaiser, Manfred Maul, Christof Zaczek
Estimating the term…
An objective for a microlithography projection system has at least one fluoride crystal lens. The effects of birefringence, which are detrimental to the image quality, are reduced if the lens axis of the crystal lens is oriented substantially perpendicular to the {100}-planes or {100}-equivalent crystallographic planes of the fluoride crystal. If two or more fluoride crystal lenses are used, they should have lens axes oriented in the (100)-, (111)-, or (110)-direction of the crystallographic structure, and they should be oriented at rotated positions relative to each other. The birefringence-related effects are further reduced by using groups of mutually rotated (100)-lenses in combination with groups of mutually rotated (111)- or (110)-lenses. A further improvement is also achieved by applying a compensation coating to at least one optical element of the objective.
An objective comprising a plurality of lenses, wherein at least one lens consists of fluoride crystal with a cubic lattice structure and wherein said fluoride crystal lens is a (100)-lens with a lens axis oriented approximately perpendicular to the {100}-planes or to crystallographic planes that are equivalent to the {100}-planes of the fluoride crystal, wherein light rays travel inside the objective from an object plane to an image plane and at least one light ray among said light rays has a ray angle inside the (100)-lens of more than 25° relative to the lens axis.
An objective comprising a plurality of lenses, wherein at least one lensconsists of fluoride crystal with a cubic lattice structure and wherein said fluoride crystal lens is a (100)-lens with a lens axis oriented approximately perpendicular to the {100}-planes or to crystallographic planes that are equivalent to the {100}-planes of the fluoride crystal, further comprising a diaphragm in a diaphragm plane, wherein the diaphragm has a diaphragm diameter and the (100)-lens has a lens diameter that is smaller than 85% of the diaphragm diameter.
An objective comprising a plurality of lenses, wherein at least one lens consists of fluoride crystal with a cubic lattice structure and wherein said fluoride crystal lens is a (100)-lens with a lens axis oriented approximately perpendicular to the {100}-planes or to crystallographic planes that are equivalent to the {100}-planes of the fluoride crystal, further comprising an image plane, wherein the (100)-lens is the lens nearest to the image plane among said plurality of lenses.
An objective comprising a plurality of lenses, wherein at least one lens consists of fluoride crystal and wherein said fluoride crystal lens is a (100)-lens with a lens axis oriented approximately perpendicular to the {100}-planes or to crystallographic planes that are equivalent to the {100}-planes of the fluoride crystal.
Dependencies are inferred from the claim text.