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US 2008/0007705 A1Published application
In-Situ Interferometer Arrangement
AssigneeLitel Instruments
InventorsAdlai Smith, Robert Hunter
Life of this patent
Estimating the term…
Abstract
An in-situ interferometer includes an image modifying optic that produces light ray bundles. The light ray bundles are projected onto a reticle with a plurality of measurement fiducials encoded onto a face of the reticle. The measurement fiducials are exposed onto a sensing plane and their locations measured. Aberrations in the projection system are determined from the measurements of the exposed reticles.
Claims29
A reticle comprising:
- an array of field points, wherein each field point comprises an array of fiducials;
- and
- an array of optical elements, wherein an optical element is associated with each of the field points.
A projection lithography tool comprising:
- an effective light source comprising
- a light source;
- a condensing lens configured to accept light from the light source;
- and
- an illumination modifying optic between the light source and the condensing lens, wherein the illumination modifying optic is located at a conjugate aperture stop of an image plane of a projection lens system, the illumination modifying optic is configured such that light from the light source that passes through the illumination modifying optic and condensing lens forms a plurality of light ray bundles with corresponding chief rays;
- a reticle upon which the light ray bundles are projected, the reticle comprising:
- an array of field points, wherein each field point comprises an array of fiducials;
- and
- an array of optical elements, wherein an optical element is associated with each of the field points;
- and
- an upper lens group wherein the conjugate aperture stop is imaged by the combination of the condenser lens and the upper lens group onto an aperture stop, the upper lens group further including optics to image the fiducials onto a sensing plane.
8 more elements
An illumination source comprising:
- providing a light source;
- providing a condensing lens configured to accept light from the light source;
- providing an illumination modifying optic between the light source and the condensing lens, wherein the illumination modifying optic is located at a conjugate aperture stop of an image plane of a projection lens system, wherein the illumination modifying optic is configured such that light from the light source that passes through the illumination modifying optic and condensing lens forms a plurality of light ray bundles with corresponding chief rays;
- and
- placing a lens on a side of the condensing lens opposite from the illumination modifying optic, wherein angles of incidence of the chief rays within the respective light ray bundles onto the lens vary sufficiently to overfill the lens pupil.
2 more elements
Dependencies are inferred from the claim text.