Spectrometric metrology of workpieces using a permanent window as a spectral reference
AssigneeApplied Materials, Inc.
InventorsEdgar Genio, Edward W. Budiarto
Life of this patent
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Abstract
In a spectrographic workpiece metrology system having an optical viewing window, the viewing window is calibrated against a reference sample of a known absolute reflectance spectrum to produce a normalized reflectance spectrum of the reference sample, which is combined with the absolute reflectance spectrum to produce a correction factor. Successive production workpieces are measured through the window and calibrated against the viewing window reflectance, and transformed to absolute reflectance spectra using the same correction factor without having to re-load the reference sample.
Claims17
A method of measuring the reflectance spectrum of a workpiece using an optical sensing apparatus having a viewing window facing a workpiece support surface, comprising:
- computing a correction function by combining together (A) a predetermined reflectance spectrum of a reference sample and (B) a measured reflectance spectrum of said reference sample that has been (a) measured through said viewing window and (h) normalized with a reflectance spectrum of said viewing window;
- measuring through said viewing window a reflectance spectrum of a workpiece, normalizing said reflectance spectrum of the workpiece with the reflectance spectrum of said viewing window, and computing a reflectance spectrum of the workpiece by combining the normalized workpiece reflectance spectrum with said correction function.
A method of performing spectrographic workpiece metrology through an optical viewing window, comprising:
- calibrating the viewing window against a reference sample of a predetermined reflectance spectrum to produce a normalized reflectance spectrum of the reference sample;
- combining the normalized reflectance spectrum with the predetermined reflectance spectrum to produce a correction factor;
- measuring reflectance spectra of a workpiece through said window and normalizing said reflectance spectra of the workpiece against the viewing window reflectance spectrum to produce a normalized workpiece reflectance spectrum;
- and
- transforming the normalized workpiece reflectance spectrum using said correction factor.
Dependencies are inferred from the claim text.