Metric for recognizing correct library spectrum
AssigneeApplied Materials, Inc.
InventorKiran Lall Shrestha
Life of this patent
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Abstract
A method of controlling polishing of a substrate is described. A controller stores a library having a plurality of reference spectra. The controller polishes a substrate and measures a sequence of spectra of light from the substrate during polishing. For each measured spectrum of the sequence of spectra, the controller finds a best matching reference spectrum from the plurality of reference spectra and generates a sequence of best matching reference spectra. The controller uses a cell counting technique for finding the best matching reference spectrum. The controller determines at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of best matching reference spectra.
Claims18
A method of controlling polishing, comprising:
- storing a library having a plurality of reference spectra;
- polishing a substrate;
- measuring a sequence of spectra of light from the substrate during polishing;
- for each measured spectrum of the sequence of spectra, finding a best matching reference spectrum from the plurality of reference spectra to generate a sequence of best matching reference spectra, wherein finding the best matching reference spectrum uses a cell counting technique;
- and
- determining at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of best matching reference spectra.
A polishing apparatus, comprising:
- a support to hold a polishing pad;
- a carrier head to hold a substrate against the polishing pad;
- a motor to generate relative motion between the carrier head and the support to polish the substrate;
- an optical monitoring system to measure a sequence of spectra of light from the substrate while the substrate is being polished;
- and
- a controller configured to
- store a library having a plurality of reference spectra, each reference spectrum of the plurality of reference spectra having a stored associated characterizing value,
- for each measured spectrum of the sequence of spectra, find a best matching reference spectrum using a cell counting technique;
- and
- determine at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of best matching reference spectra.
A computer program product, tangibly embodied in a machine readable storage device, comprising instructions to:
- store a library having a plurality of reference spectra;
- polish a substrate;
- measure a sequence of spectra of light from the substrate during polishing;
- for each measured spectrum of the sequence of spectra, find a best matching reference spectrum using a cell counting technique;
- and
- determine at least one of a polishing endpoint or an adjustment for a polishing rate based on the sequence of best matching reference spectra.
Dependencies are inferred from the claim text.