Expediting spectral measurement in semiconductor device fabrication

Patent metadata

Field	Value
Publication number	US-11237120-B2
Application number	US-202016934123-A
Country	US
Kind code	B2
Filing date	Jul 21, 2020
Priority date	Oct 4, 2016
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

A device and method for expediting spectral measurement in metrological activities during semiconductor device fabrication through interferometric spectroscopy of white light illumination during calibration, overlay, and recipe creation.

First claim

What is claimed is:

1. An interferometric-spectroscopy metrology tool comprising:
an interferometric microscope configured to create an interferogram from white light illumination, the microscope having:
a horizontally conveyable reference mirror or a conveyable beam splitter cube,
a focal lens fixed at a focal distance from a processed wafer;

a two-dimensional, pixel-array detector configured to capture multiple, pixel-specific interferograms in accordance with a changing optical path distance of light beams derived from the white light illumination; and
a computer configured to apply a Fourier transform on each of the pixel-specific interferograms so as to generate a pixel-specific frequency spectrum associated with each corresponding area of the processed wafer, wherein the computer is further configured to determine refractive index from the frequency spectrum.

2. The tool of claim 1 , wherein the computer is further configured to construct a synthetic image of at least one chosen centroid wavelength and respective chosen bandwidth.

3. The tool of claim 2 , wherein the computer is further configured to apply a metric to the synthetic image.

4. The tool of claim 3 , wherein the metric is selected from the group consisting of overlay metric Region of Investigation (ROI) of the processed wafer, average reflectivity, 3S, contrast, and target asymmetry.

5. The tool of claim 1 , wherein the computer is further configured to determine film thickness from the frequency spectrum.

6. The tool of claim 5 , wherein the computer is further configured to correct an overlay measurement resulting from deviation of the film thickness.

7. The tool of claim 1 , wherein the computer is further configured to correct an overlay measurement resulting from deviation of the refractive index.

8. A method of expediting acquisition of hyperspectral data in semiconductor
device fabrication metrology, the method comprising:
splitting white light illumination with an interferometric microscope into two light beams;
changing an optical path distance traveled by the lights beams while maintaining focus on the processed wafer;
capturing a pixel-specific interferograms on a two-dimensional, pixel-array detector in accordance with the changing optical path distance traveled by the light beams;
applying a Fourier transformation to each a pixel-specific interferogram so as to generate a pixel-specific frequency spectrum of the processed wafer; and
assigning pixel grey levels proportional to a chosen pixel, centroid frequency and bandwidth.

9. The method of claim 8 , wherein the changing the optical path distance is implemented through horizontal conveyance of a reference mirror.

10. The method of claim 8 , wherein the changing the optical path distance is implemented through conveyance of a beam splitter.

11. The method of claim 8 , further comprising determining film thickness from the frequency spectrum.

12. The method of claim 11 , further comprising correcting an overlay measurement resulting from deviation of the film thickness.

13. The method of claim 8 , further comprising determining refractive index from the frequency spectrum.

14. The method of claim 13 , further comprising correcting an overlay measurement resulting from deviation of the refractive index.

Assignees

• Kla Tencor Corp

Inventors

• Immer Vincent
• Marciano Tal
• Lavert Etay

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P72/0606

  Position monitoring, e.g. misposition detection or presence detection · CPC title

• G01N21/31 Primary

  Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)} · CPC title

• G03F7/70653

  Metrology techniques · CPC title

• G03F7/706837

  Data analysis, e.g. filtering, weighting, flyer removal, fingerprints or root cause analysis · CPC title