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Spectrometer measurement of diffracting structures

  • US 7,372,565 B1
  • Filed: 09/28/2006
  • Issued: 05/13/2008
  • Est. Priority Date: 09/25/2000
  • Status: Expired due to Term
First Claim
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1. An apparatus for measuring at least one of height, pitch, sidewall angle, and linewidth of a diffracting structure on a sample, said apparatus comprising:

  • a metrology device that measures the reflectance of said diffracting structure and at least one underlying layer on said sample at approximately normal incidence, the metrology device comprising;

    a broadband radiation source that produces radiation with a plurality of wavelengths;

    a polarizing element, said radiation passing through said polarizing element toward said sample, said radiation being approximately normally incident on and diffracted by said diffracting structure and the at least one underlying layer on said sample, a zeroth order diffracted radiation passing through said polarizing element;

    a detector that measures the reflectance of the zeroth order diffracted radiation;

    and a computer system for analyzing said diffraction to determine said at least one of height, pitch, sidewall angle, and linewidth of said diffracting structure on said sample, said computer system comprising;

    at least one computer coupled to said metrology device; and

    a computer program executed by said at least one computer, wherein said computer program includes instructions for;

    extracting spectral information from the measured reflectance of the zeroth order diffracted radiation;

    constructing an optical model simulating said diffracting structure using at least one variable parameter of height, pitch, sidewall angle, and linewidth and a variable parameter of the at least one underlying layer;

    calculating spectral information for said optical model; and

    curve fitting said calculated spectral information to said extracted spectral information to determine said at least one of height, pitch, sidewall angle, and linewidth of said diffracting structure and the variable parameter of the at least one underlying layer on said sample;

    wherein constructing an optical model, calculating spectral information for said optical model, and curve fitting are performed in real-time.

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