Lithographic apparatus and method for optimizing an illumination source using isofocal compensation
First Claim
1. A method for optimizing an illumination condition of a lithographic apparatus by computer simulation using isofocal compensation, the lithographic apparatus comprising an illuminator configured to provide an illumination arrangement, a projection system and a mask having at least one pattern to be printed on a substrate, the method comprising:
- defining a lithographic pattern to be printed on the substrate;
selecting a simulation model;
selecting a grid of source points in a pupil plane of the illuminator;
calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model;
calculating a metric representing variation of the separate responses for individual source points with defocus; and
adjusting an illumination arrangement based on analysis of the metric.
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Abstract
A method for optimizing the illumination conditions of a lithographic apparatus by computer simulation using isofocal compensation, the lithographic apparatus including an illuminator, a projection system and a mask having at least one pattern to be printed on a substrate. This method includes defining a lithographic pattern to be printed on the substrate, selecting a simulation model, selecting a grid of source points in a pupil plane of the illuminator, calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model, calculating a metric representing variation of the separate responses for individual source points with defocus and adjusting an illumination arrangement based on analysis of the metric.
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Citations
25 Claims
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1. A method for optimizing an illumination condition of a lithographic apparatus by computer simulation using isofocal compensation, the lithographic apparatus comprising an illuminator configured to provide an illumination arrangement, a projection system and a mask having at least one pattern to be printed on a substrate, the method comprising:
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defining a lithographic pattern to be printed on the substrate;
selecting a simulation model;
selecting a grid of source points in a pupil plane of the illuminator;
calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model;
calculating a metric representing variation of the separate responses for individual source points with defocus; and
adjusting an illumination arrangement based on analysis of the metric. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 24, 25)
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22. A lithographic projection apparatus comprising:
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an illumination system to provide a projection beam of radiation a support structure to support patterning structure which can be used to pattern the projection beam according to a desired pattern;
a substrate table to hold a substrate;
a projection system to project the patterned beam onto a target portion of the substrate;
a processor to define a lithographic pattern to be printed on the substrate, to select a grid of source points in a pupil plane of the illumination system, to calculate separate responses for individual source points, each of the responses representing a result of a single or series of simulations using a simulation model, to calculate a metric representing variation of the separate responses for individual source points with defocus; and
to calculate an optimized illumination arrangement based on analysis of the metric; and
a selectably variable beam controller that is adapted to modify a cross-sectional intensity distribution in the projection beam exiting the illumination system in accordance with the optimized illumination arrangement calculated by the processor.
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23. A machine readable medium encoded with machine executable instructions for optimizing an illumination condition of an illuminator using isofocal compensation according to a method comprising:
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defining a lithographic pattern to be printed on a substrate;
selecting a simulation model;
selecting a grid of source points in a pupil plane of the illuminator;
calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model;
calculating a metric representing variation of the separate responses for individual source points with defocus; and
adjusting an illumination arrangement based on analysis of the metric.
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Specification