Sem image alignment
AssigneeASML Netherlands B.V.
InventorsMarleen KOOIMAN, Joost VAN BREE
Life of this patent
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Abstract
A method of determining offsets between a plurality of data sets, each data set representing a sampling area of a pattern formed on a sample, wherein each sampling area derives from a predetermined portion of a mask pattern, the method comprising: detecting a fingerprint of the mask pattern in noise of the data sets; and determining offsets based on the fingerprint of the mask pattern.
Claims20
A method of determining offsets between a plurality of data sets, each data set representing a sampling area of a pattern formed on a sample, wherein each sampling area derives from a predetermined portion of a mask pattern, the method comprising:
- detecting a fingerprint of the mask pattern in noise of the data sets;
- and
- determining offsets based on the fingerprint of the mask pattern.
An inspection method comprising:
- using a scanning electron microscope to obtain a plurality of SEM images by scanning a plurality of copies of a predetermined pattern in one or more samples;
- extracting a contour of a line in each of the plurality of SEM images to obtain a plurality of line contours;
- determining an initial set of offsets for each of the line contours;
- calculating a mean contour based on the line contours and the initial set of offsets;
- and
- iteratively calculating an improved set of offsets that maximises a correlation between each of the contour lines and the mean contour and updating the mean contour.
A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions, when executed by a computer or a controller of a scanning electron microscope, implementing a method comprising:
- detecting a fingerprint of a mask pattern in noise of data sets;
- and
- determining offsets based on the fingerprint of the mask pattern.
A system comprising:
- a scanning electron microscope (SEM) configured to scan with an electron beam and generate an image;
- and
- a non-transitory machine-readable medium storing instructions which, when executed by a processor, cause the processor in co-operation with the SEM to perform operations comprising:
- detecting a fingerprint of a mask pattern in noise of data sets;
- and
- determining offsets based on the fingerprint of the mask pattern.
Dependencies are inferred from the claim text.