Apodization measurement for lithographic apparatus
AssigneeASML Netherlands B.V.
InventorsMarcus Van De Kerkhof, Haico Kok
Life of this patent
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Abstract
A method and apparatus are provided for measuring the apodization of projection optics for use in a lithographic apparatus, the projection optics having an object plane where, in use, a reticle is placed, a pupil plane, and an image plane where, in use, a wafer is placed. The method includes placing one or more Appropriate apertures in said object plane for creating a substantially uniform light distribution, illuminating the or each aperture and measuring the intensity distribution at a plane which is conjugate to the pupil plane in order to calculate the apodization of the projection optics.
Claims21
A method of measuring apodization of projection optics for use in a lithographic apparatus, the projection optics having an object plane where, in use, a reticle is placed, a pupil plane, and an image plane where, in use, a wafer is placed, the method comprising:
- placing one or more apertures in said object plane for creating a substantially uniform light distribution;
- illuminating the aperture;
- and
- measuring an intensity distribution at a plane which is conjugate to the pupil plane in order to calculate the apodization of the projection optics.
Apparatus for measuring apodization of projection optics for use in a lithographic apparatus, the projection optics having an object plane where, in use, a reticle is placed, a pupil plane, and an image plane where, in use, a wafer is placed, the apparatus comprising:
- one or more apertures located in said object plane for creating a substantially uniform light distribution;
- an illumination source for illuminating the or each aperture;
- and
- a sensor for measuring an intensity distribution at a plane which is conjugate to the pupil plane in order to calculate the apodization of the projection optics.
A lithographic apparatus comprising:
- an illumination system for conditioning a beam of radiation;
- a support structure for supporting a patterning device, the patterning device serving to impart the projection beam with a pattern in its cross-section;
- a substrate table for holding a substrate;
- projection optics for projecting the patterned beam onto a target portion of the substrate and having an object plane, where, in use, the patterning device is placed, a pupil plane, and an image plane where, in use, the substrate is placed;
- one or more apertures located in said object plane for creating a substantially uniform light distribution;
- and
- a sensor for measuring the intensity distribution at a plane which is conjugate to the pupil plane in order to calculate an apodization of the projection optics.
Dependencies are inferred from the claim text.