Photolithographic projection apparatus using light in the far ultraviolet
AssigneeBell Telephone Laboratories, Incorporated
InventorAlan D. White
Life of this patent
Estimating the term…
Abstract
A lens design for submicron photolithography images a mask (21) onto a semiconductor wafer (23) using light in the far ultraviolet. Illustratively, the lens design is a modified Dyson imaging system comprising a thick plano-convex lens (31), a beam splitter, adjacent to the planar surface of the plano-convex lens comprising two right angle prisms (34, 35) separated by a dielectric interface (36), and an aspherical mirror (32) located on the convex side of the lens. Stress-induced birefringence is used to rotate the plane of polarization of the object radiation.
Claims11
An image projection apparatus for radiation in the far ultraviolet, effective to project radiation from an object plane onto an image plane, comprising:
- a polarizing beam-splitter plano-convex lens combination, the convex surface of said combination having its apex located on an optical path from said object plane to said image plane that is normal to said convex surface at its apex, said combination having a first planar surface proximate to said object plane, and a second planar surface proximate to said image plane;
- an aspherical mirror, whose center of curvature is substantially coincident with the center of curvature of said convex surface, located on the convex side of said combination and centered on said optical path;
- and
- means for inducing sufficient birefringence into said lens to cause quarter-wave retardation of radiation traversing the lens;
- the distance along said optical path between said first surface and said apex of said second convex surface and the distance along said path from said apex of said convex surface to said second surface being mutually approximately equal to the radius of curvature of said convex surface.
An image projection apparatus for radiation in the far ultraviolet, effective to project radiation from an object plane onto a perpendicular plane forming an image plane, comprising:
- a thick plano-convex lens, the convex surface of said lens having its apex located on an optical path from said object plane to said image plane that is normal to said convex surface at its apex,
- an aspherical mirror, whose center of curvature is substantially coincident with the center of curvature of said convex surface, located on the convex side of said lens and centered on said optical path,
- a polarizing beam splitter, adjacent to the planar surface of said lens, comprising a first right angle prism having a first planar surface proximate and parallel to said object plane, and a second right angle prism having a second planar surface proximate and parallel to said image plane,
- said prisms being separated by a flowing liquid gate, and
- means for inducing sufficient birefringence into said plano-convex lens to cause quarter-wave retardation of radiation traversing said lens;
- the distance along said optical path between said first surface and said apex of said convex surface and the distance along said path from said apex to said second surface being mutually approximately equal to the radius of curvature of said convex surface.
An image projection apparatus for radiation in the far ultraviolet, effective to project radiation from an object plane onto an image plane, comprising:
- a polarizing beam-splitter plano-convex lens combination, said combination having a first planar surface proximate to said object plane and a second planar surface proximate to said image plane;
- an aspherical mirror, located on the convex side of said combination, having a center of curvature substantially coincident with the center of curvature of the convex surface of said combination;
- and
- means for inducing sufficient birefringence into said lens to cause quarter-wave retardation of radiation traversing the lens.
Dependencies are inferred from the claim text.