Method and apparatus for determining surface layer thickness using continuous multi-wavelength surface scanning

  • US 7,271,921 B2
  • Filed: 01/09/2004
  • Issued: 09/18/2007
  • Est. Priority Date: 07/23/2003
  • Status: Active Grant
First Claim
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1. A method for conducting surface inspections comprising:

  • providing a workpiece having a at least one partially transmissive layer formed thereon;

    scanning the surface of the workpiece with at least two light beams to generate at least two reflected light signals having light intensity values;

    detecting the light intensity of the reflected light signals; and

    processing only the detected light intensity values of the reflected light signals to obtain thickness measurements for the at least one partially transmissive layer formed at the surface of the workpiece, wherein said processing comprises;

    accessing a parametric reflected intensity curve that associates thickness of the at least one partially transmissive layer with two detected light intensity values for the reflected light signals generated by the at least two light beams; and

    comparing the two detected light intensity values with the light intensity values of the parametric curve to obtain thickness measurements for the at least one partially transmissive layer.

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