Optical metrology optimization for repetitive structures
First Claim
1. A method of determining the profile parameters of a repeating structure formed on a wafer using an optical metrology model, the optical metrology model having profile parameters associated with a top-view of the structure and profile parameters associated with a cross-sectional view of the structure, the method comprising:
- a) characterizing a top-view profile of the structure, the profile of the structure having profile parameters;
b) selecting the profile parameters to represent variations in the top-view profile of the structure;
c) selecting profile parameters associated with a cross-sectional view profile of the structure;
d) integrating the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model; and
e) storing the optical metrology model.
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Abstract
The top-view profiles of repeating structures in a wafer are characterized and parameters to represent variations in the top-view profile of the repeating structures are selected. An optical metrology model is developed that includes the selected top-view profile parameters of the repeating structures. The optimized optical metrology model is used to generate simulated diffraction signals that are compared to measured diffraction signals.
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Citations
29 Claims
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1. A method of determining the profile parameters of a repeating structure formed on a wafer using an optical metrology model, the optical metrology model having profile parameters associated with a top-view of the structure and profile parameters associated with a cross-sectional view of the structure, the method comprising:
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a) characterizing a top-view profile of the structure, the profile of the structure having profile parameters; b) selecting the profile parameters to represent variations in the top-view profile of the structure; c) selecting profile parameters associated with a cross-sectional view profile of the structure; d) integrating the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model; and e) storing the optical metrology model. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of modeling repeating structures in a wafer for optical metrology, the method comprising:
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a) setting one or more termination criteria; b) defining a unit cell of the repeating structures in a wafer, the unit cell having one or more features; c) fitting one or more basic shapes to the top-view profile of the one or more features of the unit cell, the one or more basic shapes having parameters; d) selecting the parameters of the one or more basic shapes to represent variations in the top-view profile of the structures; e) selecting profile parameters associated with a cross-sectional view profile of the structure; f) integrating the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model; and g) storing the optical metrology model. - View Dependent Claims (21, 22)
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23. A system for optimizing selection of profile parameters of an optical metrology model for use in modeling repeating structures in a wafer, the optical metrology model having profile parameters associated with a top-view of the structure and profile parameters associated with a cross-sectional view of the structure, the system comprising:
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a model preprocessor configured to characterize a top-view profile of structure, the profile of the structure having profile parameters;
select the profile parameters to represent variations in the top-view profile of the structures;
select profile parameters associated with a cross-sectional view profile of the structure; and
integrate the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model;a metrology model optimizer configured to optimize the optical metrology model using one or more criteria and to generate one or more simulated diffraction signals based on the optimized metrology model; a metrology device configured to measure diffracted signals off the repeating structure; a comparator configured to determine if one or more termination criteria are met based on calculations using the generated diffraction signals; and a model adjuster configured to alter characterization of the top-view profile of the structure, selection of profile parameters to represent variations in the top-view profile of the structures; and
selection of profile parameters associated with the cross-sectional view profile of the structure. - View Dependent Claims (24, 25, 26)
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27. A computer-readable storage medium containing computer executable instructions for causing a computer to optimizing selection of profile parameters of an optical metrology model for use in modeling repeating structures in a wafer, the optical metrology model having profile parameters associated with a top-view of the structure and profile parameters associated with a cross-sectional view of the structure, comprising instructions for:
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a) characterizing a top-view profile of structure, the profile of the structure having profile parameters; b) selecting the profile parameters to represent variations in the top-view profile of the structures; c) selecting profile parameters associated with a cross-sectional view profile of the structure; d) integrating the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model; e) optimizing the optical metrology model; f) creating a set of profile parameters and simulated diffraction signals using the optimized optical metrology model; g) extracting a best match simulated diffraction signal using the set of profile parameters and associated simulated diffraction signals and one or more measured diffraction signals; h) when the best match simulated diffraction signal and the measured diffraction signals do not match within one or more matching criteria, altering the characterization and/or selection of profile parameters; and i) iterating a), b), c), d), e), f), g), and h) until the best match simulated diffraction signal and the measured diffraction signal match within the one or more matching criteria.
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28. A computer-readable storage medium containing computer executable instructions for causing a computer to optimize an optical metrology model for use in measuring a wafer structure, comprising instructions for:
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a) setting one or more termination criteria; b) defining a unit cell of the repeating structures in a wafer, the unit cell having one or more features; c) fitting one or more basic shapes to the top-view profile of the one or more features of the unit cell, the one or more basic shapes having parameters; d) selecting the parameters of the one or more basic shapes to represent variations in the top-view profile of the structures; e) selecting profile parameters associated with a cross-sectional view profile of the structure; f) integrating the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model; g) optimizing the optical metrology model using one or more measured diffraction signals off the repeating structure, the optimization generating a simulated diffraction signal; h) comparing the calculated one or more termination criteria with the preset one or more termination criteria using the generated simulated diffraction signal.
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29. A computer-readable storage medium containing computer executable instructions for causing a computer to optimizing selection of profile parameters of an optical metrology model for use in modeling repeating structures in a wafer, the optical metrology model having profile parameters associated with a top-view of the structure and profile parameters associated with a cross-sectional view of the structure, comprising instructions for:
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a) characterizing a top-view profile of the structure, the profile of the structure having profile parameters; b) selecting the profile parameters to represent variations in the top-view profile of the structure; c) selecting profile parameters associated with a cross-sectional view profile of the structure; d) integrating the selected profile parameters representing the top-view profile and the cross-sectional view profile of the structure into an optical metrology model; and e) storing the optical metrology model.
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Specification