System and method for characterizing aerial image quality in a lithography system
First Claim
1. A method for characterizing aerial image quality in a lithography system, comprising:
- measuring light intensity, using an image sensor array, at a number of samples of statistically-determined, non-adjacent locations within an aerial image produced by a lithography system without obtaining a number of measurements sufficient to reconstruct a complete feature of the aerial image; and
using the samples of measured light intensity to determine a characteristic representative of the quality of the entire aerial image.
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Abstract
While a high-resolution 2-dimensional image reconstruction is expected to give the maximum possible amount of information on the aerial image in a projection system, relevant information regarding image quality can be derived from a statistical evaluation of image values. Relevant statistical image data can be derived by sampling at a multitude of non-adjacent locations across a large area, rather than by scanning over many adjacent locations on a small area. Examples of the benefits of the present invention include: (1) it generally does not rely on very precise, repeatable fine alignment of the image sensor array with respect to the mask and/or the projected image; (2) a large number of individual sensor elements are utilized, and image data is generated from a large set of signal values; and (3) it can generate relevant data to assess aerial image quality in a very short data acquisition time.
107 Citations
22 Claims
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1. A method for characterizing aerial image quality in a lithography system, comprising:
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measuring light intensity, using an image sensor array, at a number of samples of statistically-determined, non-adjacent locations within an aerial image produced by a lithography system without obtaining a number of measurements sufficient to reconstruct a complete feature of the aerial image; and
using the samples of measured light intensity to determine a characteristic representative of the quality of the entire aerial image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for characterizing aerial image quality in a lithography system, comprising:
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measuring light intensity, using an image sensor array, at a single set of non-adjacent locations within an aerial image produced by a lithography system, the measured light intensity being obtained without translation of the image sensor array; and
using the measured light intensity to determine a characteristic representative of the quality of the entire aerial image without the need to graphically reconstruct an entire feature of the aerial image. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for characterizing aerial image quality in a lithography system, comprising:
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placing an image sensor array in a lithography tool, the image sensor array having a plurality of apertures of equal diameter;
illuminating a mask to produce an aerial image projected onto the image sensor array;
measuring light intensity using the image sensor array at a first set of locations within the aerial image;
moving the image sensor array a distance greater than the aperture diameter such that the plurality of apertures are at a second set of locations;
measuring light intensity using the image sensor array at the second set of locations; and
using the measurements of light intensity at the first set of locations and the measurements of light intensity at the second set of locations to determine a characteristic representative of the quality of the entire aerial image, wherein the measurements of light intensity at the first set of locations and the measurements of light intensity at the second set of locations are not sufficient to graphically reconstruct a complete feature of the aerial image.
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19. A system for characterizing aerial image quality in a lithography system, comprising:
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an image sensor array capable of being loaded into a lithography tool, the lithography tool configured to project an aerial image onto the image sensor array;
a data storage module capable of receiving and storing measurements of light intensity from the image sensor array; and
an image characterization module configured to receive stored measurements of light intensity from the data storage module and to determine a characteristic representative of the quality of the entire aerial image using measurements of light intensity measured by the image sensor array at a statistically-determined sample of non-adjacent locations within the aerial image;
wherein the image characterization module is configured to determine the characteristic representative of the quality of the entire aerial image using a fewer number of measurements than would be required to reconstruct a complete feature of the aerial image. - View Dependent Claims (20)
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21. A system for characterizing aerial image quality in a lithography system, comprising:
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an image sensor array capable of being loaded into a lithography tool, the lithography tool configured to project an aerial image onto the image sensor array;
a data storage module capable of receiving and storing measurements of light intensity from the image sensor array; and
an image characterization module configured to receive stored measurements of light intensity from the data storage module and to determine a characteristic representative of the quality of the entire aerial image using measurements of light intensity of less than the entire aerial image measured by the image sensor array;
wherein the image characterization module is configured to determine the characteristic representative of the quality of the entire aerial image using fewer measurements than would be required for extracting an entire feature of the aerial image. - View Dependent Claims (22)
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Specification