Sughrue Mion, PLLC
Catadioptric projection objective
Catadioptric projection objective (1) for microlithography for imaging an object field (3) in an object plane (5) onto an image field (7) in an image plane (9). The objective includes a first partial objective (11) imaging the object field onto a first real intermediate image (13), a second partial objective (15) imaging the first intermediate image onto a second real intermediate image (17), and a third partial objective (19) imaging the second intermediate image onto the image field. The second partial objective is a catadioptric objective having exactly one concave mirror and having at least one lens (L21, L22). A first folding mirror (23) deflects the radiation from the object plane toward the concave mirror and a second folding mirror (25) deflects the radiation from the concave mirror toward the image plane. At least one surface of a lens (L21, L22) of the second partial objective has an antireflection coating having a reflectivity of less than 0.2% for an operating wavelength of between 150 nm and 250 nm and for an angle-of-incidence range of between 0° and 30°. As an alternative or in addition, all the surfaces of the lenses of the second partial objective are configured such that the deviation from the marginal ray concentricity is greater than or equal to 20°.
Carl Zeiss SMT GmbH
G G G G G G G
G02B G02B G02B G02B G03F G03F G03F
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Toralf Thomas Vladimir Alexander
Gruner Schicketanz Kamenov Epple