Iso-reflectance wavelengths
AssigneeApplied Materials, Inc.
InventorDominic J. Benvegnu
Life of this patent
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Abstract
A method of measuring a physical characteristic of a patterned substrate comprises determining a wavelength where a first reflectance from a patterned substrate equals a second reflectance from the patterned substrate. The first and second reflectances are generated from substrate regions having different pattern densities. A physical characteristic value that is associated with the determined wavelength is identified. The value identification may be done by looking up the determined wavelength in a database, for example by referring to a graph.
Claims25
A method of measuring a physical characteristic of a patterned substrate, the method comprising:
- receiving a first reflectance spectrum and a second reflectance spectrum measured from the patterned substrate, the first and second reflectance spectra being generated from substrate regions having different pattern densities;
- determining, after receiving the first and second reflectance spectra, a wavelength where the first reflectance spectrum equals the second reflectance spectrum;
- identifying a physical characteristic value that is associated with the determined wavelength;
- and
- reporting or storing an indication of the identified physical characteristic value.
A method of measuring a thickness of a layer on a patterned substrate, the method comprising:
- directing a light beam at a first region of the layer on the patterned substrate;
- recording a first reflectance spectrum produced by the light beam reflecting off the first region;
- directing the light beam at a second region of the layer that has a different pattern density than the first region;
- recording a second reflectance spectrum produced by the light beam reflecting off the second region;
- determining, after recording the first and second reflectance spectra, a wavelength where the first and second reflectance spectra intersect;
- identifying a layer thickness that is associated with the determined wavelength;
- and
- reporting or storing an indication of the identified layer thickness.
An apparatus for measuring a physical characteristic of a patterned substrate, the apparatus comprising:
- a light source that generates a light beam to impinge on at least first and second substrate regions having different pattern densities;
- a sensor that receives a first reflectance spectrum generated from the first substrate region and a second reflectance spectrum generated from the second substrate region;
- and
- a processor configured to identify, after the sensor receives the first and second reflectance spectra, a physical characteristic value that is associated with a wavelength where the first reflectance spectrum equals the second reflectance spectrum.
A computer program product tangibly embodied in a computer-readable storage device, the computer program product including instructions that, when executed, cause a processor to perform operations comprising:
- receiving a first reflectance spectrum and a second reflectance spectrum measured from a patterned substrate, the first and second reflectance spectra being generated from substrate regions having different pattern densities;
- determining, after receiving the first and second reflectance spectra, a wavelength where the first reflectance spectrum equals the second reflectance spectrum;
- identifying a physical characteristic value that is associated with the determined wavelength;
- and
- reporting or storing an indication of the identified physical characteristic value.
A computer program product tangibly embodied in a computer-readable storage device, the computer program product including instructions that, when executed, cause a processor to perform operations comprising:
- directing a light beam at a first region of a layer on a patterned substrate;
- recording a first reflectance spectrum produced by the light beam reflecting off the first region;
- directing the light beam at a second region of the layer that has a different pattern density than the first region;
- recording a second reflectance spectrum produced by the light beam reflecting off the second region;
- determining, alter recording the first and second reflectance spectra, a wavelength wherein the first and second reflectance spectra intersect;
- identifying a layer thickness that is associated with the determined wavelength;
- and
- reporting or storing an indication of the identified layer thickness.
Dependencies are inferred from the claim text.