System and method to correct for field curvature of multi lens array
First Claim
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1. A lithographic apparatus, comprising:
- a patterning device that modulates a radiation beam; and
a projection system that projects the modulated radiation beam onto a target portion of a substrate, the projection system comprising,an array of focusing elements, configured such that each focusing element in the array of focusing elements focuses a portion of the modulated radiation beam onto the substrate,wherein the array of focusing elements comprises a non-planar correction surface that is shaped such that focal points of the focusing elements lie closer to a single plane than they would if the correction surface were planar.
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Abstract
Focal plane errors across the field of an array of focusing elements are reduced by using a non-planar correction surface, shaped such that focal points of the focusing elements lie closer to a single plane than they would if the correction surface were planar. For example, this can be used when an array of focusing elements is used in a projection system of a lithography system.
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Citations
21 Claims
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1. A lithographic apparatus, comprising:
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a patterning device that modulates a radiation beam; and a projection system that projects the modulated radiation beam onto a target portion of a substrate, the projection system comprising, an array of focusing elements, configured such that each focusing element in the array of focusing elements focuses a portion of the modulated radiation beam onto the substrate, wherein the array of focusing elements comprises a non-planar correction surface that is shaped such that focal points of the focusing elements lie closer to a single plane than they would if the correction surface were planar. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An array of focusing elements, comprising:
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a non-planar correction surface shaped such that, when a radiation beam is incident on the array of focusing elements, respective focal points of each focusing element in the array of focusing elements lie closer to a single plane than they would if the correction surface were planar, wherein each of the focusing elements focuses a portion of the radiation beam to the respective focal point for a given wavelength of radiation.
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12. A device manufacturing method, comprising:
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projecting a modulated radiation beam onto a substrate using a projection system comprising an array of focusing elements having a non-planar correction surface; and using each focusing element in the array of focusing elements to focus a portion of the modulated radiation beam onto the substrate; wherein the non-planar correction surface that is shaped such that focal points of the focusing elements lie closer to a single plane than they would if the correction surface were planar. - View Dependent Claims (13, 14)
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15. A method, comprising:
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measuring a position of focal points of an array of focusing elements when a radiation beam is incident on the array of focusing elements; determining a shape of a non-planar correction surface, based on the measuring step, such that when the correction surface is applied to the array of focusing elements, the focal points lie closer to a single plane than they did in the measuring step; and providing the array of focusing elements with the correction surface shaped according to the determining step. - View Dependent Claims (16, 17)
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18. A method of configuring a lithographic apparatus having a projection system comprising an array of focusing elements, such that each focusing element focuses a respective portion of a modulated radiation beam onto a substrate, comprising:
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measuring positions of points to which the array of focusing elements focus the respective portions of the modulated radiation beam; determining a shape of a non-planar correction surface, such that when the correction surface is applied to the array of focusing elements, the points to which the focusing elements focus the respective portions of the modulated radiation beam lie closer to a single plane than they did in the measuring step; and providing the array of focusing elements with the correction surface shaped according to the determining step. - View Dependent Claims (19, 20, 21)
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Specification