Method and apparatus for determining an overlay error
First Claim
1. A method comprising:
- measuring first scattering properties based on a first radiation detected from a first structure prior to formation of a second structure on the first structure;
constructing a first model structure based on the first scattering properties, the first model structure corresponding to the first structure;
overlaying the first model structure with an intermediate model structure;
calculating a first defect-induced overlay error between the first model structure and the intermediate model structure;
measuring second scattering properties based on a second radiation detected from the first and second structures, the second radiation being different from the first radiation;
constructing a second model structure based on the second radiation detected from the first and second structures and the first defect-induced overlay error;
replacing the intermediate model structure with the second model structure, the second model structure corresponding to the second structure;
calculating a second defect-induced overlay error between the first model structure and the second model structure, the first and second model structures being overlaid with respect to each other;
correcting an overlay measurement of a target based on the second defect-induced overlay error during production of the target using a lithography apparatus; and
adjusting a parameter of the lithography apparatus based on the second defect-induced overlay error to reduce overlay errors during production of a subsequent target using the lithography apparatus.
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Abstract
A method of, and associated apparatuses for, determining an overlay error resultant from structure defects such as asymmetry. The method comprises measuring scattering properties of a first target comprising a first structure and a second structure, constructing a model of the first structure using the measured scattering properties, the model comprising a first model structure corresponding to the first structure, modifying the model by overlaying the first model structure with an intermediate model structure, further modifying the model by replacing the intermediate model structure with a second model structure, corresponding to the second structure, calculating a second defect-induced overlay error between the first model structure and the second model structure, the first and second model structures being overlaid with respect to each other in the further modified model and determining an overlay error in a second target using the calculated second defect-induced overlay error.
25 Citations
20 Claims
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1. A method comprising:
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measuring first scattering properties based on a first radiation detected from a first structure prior to formation of a second structure on the first structure; constructing a first model structure based on the first scattering properties, the first model structure corresponding to the first structure; overlaying the first model structure with an intermediate model structure; calculating a first defect-induced overlay error between the first model structure and the intermediate model structure; measuring second scattering properties based on a second radiation detected from the first and second structures, the second radiation being different from the first radiation; constructing a second model structure based on the second radiation detected from the first and second structures and the first defect-induced overlay error; replacing the intermediate model structure with the second model structure, the second model structure corresponding to the second structure; calculating a second defect-induced overlay error between the first model structure and the second model structure, the first and second model structures being overlaid with respect to each other; correcting an overlay measurement of a target based on the second defect-induced overlay error during production of the target using a lithography apparatus; and adjusting a parameter of the lithography apparatus based on the second defect-induced overlay error to reduce overlay errors during production of a subsequent target using the lithography apparatus. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A non-transitory computer readable storage medium having program instructions stored thereon, execution of which by a processor causes the processor to perform operations comprising:
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measuring first scattering properties based on a first radiation detected from a first structure prior to formation of a second structure on the first structure; constructing a first model structure based on the first scattering properties, the first model structure corresponding to the first structure; overlaying the first model structure with an intermediate model structure; calculating a first defect-induced overlay error between the first model structure and the intermediate model structure; measuring second scattering properties based on a second radiation detected from the first and second structures, the second radiation being different from the first radiation; constructing a second model structure based on the second radiation detected from the first and second structures and the first defect-induced overlay error; replacing the intermediate model structure with the second model structure, the second model structure corresponding to the second structure; calculating a second defect-induced overlay error between the first model structure and the second model structure, the first and second model structures being overlaid with respect to each other; correcting an overlay measurement of a target based on the second defect-induced overlay error during production of the target using a lithography apparatus; and adjusting a parameter of the lithography apparatus based on the second defect-induced overlay error to reduce an overlay error during production of a subsequent target using the lithography apparatus.
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16. A lithographic system comprising:
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a lithography apparatus comprising; an illumination system configured to illuminate a pattern, and a projection system configured to project an image of the pattern onto a substrate; and an inspection apparatus comprising; an optical system configured to illuminate a first structure and a second structure positioned on the first structure; a detector configured to; measure first scattering properties based on a first radiation detected from the first structure prior to formation of the second structure on the first structure, and measure second scattering properties based on a second radiation detected from the first and second structures, the second radiation being different from the first radiation; and a processor configured to; construct a first model structure based on the first scattering properties, the first model structure corresponding to the first structure; overlay the first model structure with an intermediate model structure; calculate a first defect-induced overlay error between the first model structure and the intermediate model structure; construct a second model structure based on the second radiation detected from the first and second structures and the first defect-induced overlay error; replace the intermediate model structure with the second model structure corresponding to the second structure; calculate a second defect-induced overlay error between the first model structure and the second model structure; correct an overlay measurement of a target based on the second defect-induced overlay error during production of the target using a lithography apparatus; and adjust a parameter of the lithography apparatus based on the second defect-induced overlay error to reduce an overlay error during production of a subsequent target using the lithography apparatus.
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17. An inspection apparatus comprising:
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an optical system configured to illuminate a first structure and a second structure positioned on the first structure; a detector configured to; measure first scattering properties based on a first radiation detected from the first structure prior to formation of the second structure, and measure second scattering properties based on a second radiation detected from the first and second structures, the second radiation being different from the first radiation; and a processor configured to; construct a first model structure based on the first scattering properties, the first model structure corresponding to the first structure; overlay the first model structure with an intermediate model structure; calculate a first defect-induced overlay error between the first model structure and the intermediate model structure; construct a second model structure based on the second radiation detected from the first and second structures and the first defect-induced overlay error; replace the intermediate model structure with the second model structure corresponding to the second structure; calculate a second defect-induced overlay error between the first model structure and the second model structure; correct an overlay measurement of a target based on the second defect-induced overlay error during production of the target using a lithography apparatus; and adjust a parameter of the lithography apparatus based on the second defect-induced overlay error to reduce an overlay error during production of a subsequent target using the lithography apparatus. - View Dependent Claims (18, 19, 20)
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Specification