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US 10,897,566 B2Granted
Direct focusing with image binning in metrology tools
AssigneeKLA-Tencor Corporation
InventorsNadav Gutman, Boris Golovanevsky, Noam Gluzer
Life of this patent
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Abstract
Focusing methods and modules are provided for metrology tools and systems. Methods comprise capturing image(s) of at least two layers of a ROI in an imaging target, binning the captured image(s), deriving a focus shift from the binned captured image(s) by comparing the layers, and calculating a focus position from the derived focus shift. Disclosed methods are direct, may be carried out in parallel to a part of the overlay measurement process and provide fast and simple focus measurements that improve metrology performance.
Claims16
A method comprising:
- capturing at least one image of at least two layers of a region of interest (ROI) in an imaging target,
- binning the at least one captured image,
- using a contrast function constrained to the ROI:
- deriving a focus shift from the at least one binned captured image by comparing the at least two layers, and
- calculating a focus position by determining a vertical offset between the at least two layers using the derived focus shift and:
- if a behavior of the contrast function is parabolic, the contrast function, or
- if the behavior of the contrast function is non-parabolic, a complex function created using a transformation operator out of an inner contrast curve and an outer contrast curve of the contrast function.
4 more elements
A system comprising:
- a metrology tool comprising an optical arrangement configured to image imaging metrology targets and at least one camera configured to capture images thereof,
- wherein the system is configured to bin at least one captured image of at least two layers of a region of interest (ROI) in an imaging target, captured by the at least one camera of the metrology tool, and
- a processing unit that comprises a focus module configured to execute the following steps on the processing unit, using a contrast function constrained to the ROI:
- derive a focus shift from the at least one binned captured image by comparing the at least two layers, and
- calculate a focus position by determining a vertical offset between the at least two layers using the derived focus shift and:
- if a behavior of the contrast function is parabolic, the contrast function, or
- if the behavior of the contrast function is non-parabolic, a complex function created using a transformation operator out of an inner contrast curve and an outer contrast curve of the contrast function.
4 more elements
Dependencies are inferred from the claim text.