Sughrue Mion, PLLC
Chromatically corrected catadioptric objective and projection exposure apparatus including the same
A catadioptric objective includes a plurality of optical elements arranged along an optical axis to image a pattern from an object field in an object surface of the objective to an image field in an image surface region of the objective at an image-side numerical aperture NA with electromagnetic radiation from a wavelength band around a central wavelength λ. The optical elements include a concave mirror and a plurality of lenses. The projection objective forms an image of the pattern in a respective Petzval surface for each wavelength λ of a wavelength band, the Petzval surfaces deviating from each other for different wavelengths. In embodiments, a longitudinal departure p of the Petzval surface at a given wavelength from a planar reference surface at an edge field point of the image field (at maximum image height y′), measured parallel to the optical axis in the image surface region, varies with the wavelength λ according to dp/dλ<(0.2λ/NA2)/nm.
Carl Zeiss SMT AG
G G G
G03F G02B G02B
inventional additional inventional
Alexander
Epple