1985-05-10
1987-12-08
Corbin, John K.
350505, 350444, G02B 1700
Patent
active
047115351
ABSTRACT:
The present invention is directed to Optical Lithographic Systems which are particularly adapted, among many other possible uses, for use in effecting exposure of photoresist-coated semiconductor wafers, having a ring field projection system which includes at least one concave and one convex mirror arranged around an optical axis in face-to-face relationship with their centers of curvature being nearly concentric and falling on the axis, the convex mirror being smaller than and having a smaller radius of curvature than the concave mirror, an object location and a conjugate real image location, said convex mirror being positioned to reflect to the concave mirror light from the object location initially reflected from the concave mirror whereby light from the object location will be reflected at least twice at said concave mirror and at least once at the convex mirror before being focused at the image location, elements for limiting the image field to an annular zone centered about the optical axis, a first thick, flat parallel plate mounted in the light path between the object and image locations adjacent the object location, a second thick, flat parallel plate nearly identical to the first plate mounted in the light path between the object and image locations adjacent the image location, a first pair of symmetrically disposed nearly concentric meniscus elements mounted in the light path between the object and image locations at a spaced distance from the plates, respectively, a second pair of symmetrically disposed meniscus elements mounted in the light path between the object and image locations adjacent the first pair of meniscus elements, and the plates and elements being constructed and arranged so that the meniscus elements reduce spherical aberration of the principal rays in the system and introduce chromatic aberrations which are substantially cancelled by the thick, flat parallel plates.
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"New Catadioptric Meniscus System"; D. D. Maksutov; Journal of the Optical Society of America, vol. 34, No. 5; May 1944.
"Unit Magnification Optical System Without Seidel Aberrations"; J. Dyson; Journal of the Optical Society of America, vol. 49, No. 7; Jul. 1959.
Corbin John K.
Dzierzynski P. M.
Fattibene Paul A.
Grimes Edwin T.
Murphy Thomas P.
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