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US 2020/0401053 A1Published application
Scan Signal Characterization Diagnostics
AssigneesASML Netherlands B.V., ASML Holding N.V.
InventorsCornelis Melchior BROUWER, Krishanu SHOME
Life of this patent
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Abstract
A system for and method of processing a wafer in which a scan signal is analyzed locally to extract information about alignment, overlay, mark quality, wafer quality, and the like.
Claims22
-21. (canceled)
An apparatus for controlling processing of a wafer in a lithographic apparatus, the apparatus comprising:
- a light source configured to illuminate at least a portion of the wafer;
- a sensor configured to sense light after interacting with the portion of the wafer and generate a scan signal indicative of the sensed light;
- and
- a processor configured to receive the scan signal and to generate a plurality of local fit coefficients respectively for each of a plurality of samples of the scan signal and to generate a control signal based at least in part on the plurality of local fit coefficients;
- and
- a controller configured to receive the control signal and control at least one aspect of processing the wafer based at least in part on the control signal.
3 more elements
A system for aligning a wafer in a lithographic apparatus, the wafer including at least one alignment mark, the system comprising:
- a light source configured to illuminate the mark;
- a sensor configured to sense light after interacting with the mark and to generate an alignment scan signal indicative of the light from the mark;
- and
- a processor configured to receive the signal and to generate a respective at least one local fit coefficient for each of a plurality of samples of the signal,
- wherein the lithographic apparatus is configured to use the at least one local fit coefficient to adjust alignment of the wafer.
2 more elements
A system for aligning a wafer in a lithographic apparatus, the wafer including at least one alignment mark, the system comprising:
- a light source configured to illuminate the mark;
- a sensor configured to sense light after interacting with the mark and to generate an alignment scan signal indicative of the light from the mark;
- and
- a processor configured to receive the signal and to generate a respective local FFT fit coefficient for each of a plurality of samples of the signal to generate a corresponding plurality of local FFT fit coefficients for the plurality of samples, and to generate a respective local DC fit coefficient for each of a plurality of samples of the signal to generate a corresponding plurality of local DC fit coefficients for the plurality of samples, and for each sample subtract a respective one of the plurality of local FFT fit coefficients and a respective one of the plurality of DC fit coefficients from the alignment signal for the sample to obtain a residual signal for the plurality of samples,
- wherein the lithographic apparatus is configured to use the residual signal to adjust alignment of the wafer.
2 more elements
Dependencies are inferred from the claim text.