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Optical measurements of fine line parameters in integrated circuit processes

  • US 4,408,884 A
  • Filed: 06/29/1981
  • Issued: 10/11/1983
  • Est. Priority Date: 06/29/1981
  • Status: Expired due to Term
First Claim
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1. In a method for optically measuring the line parameters including line width dimensions, line edge profile or line thicknesses of a diffraction pattern of material disposed on a test sample, said diffraction pattern comprised of a planar array of spaced strips of material having a strip width a and periodicity d, including the steps for exposing and diffraction pattern to a beam of monochromatic light to diffract said beam into diffracted beams of various orders, and for detecting and measuring the intensity of at least two of the diffracted beams to obtain at least two intensity signals, wherein the improvement comprises the steps of:

  • scanning said light beam over the grating pattern of the test sample,the beam having a diameter substantially greater than the width of the grating strips, andgenerating continuously information signals representing the diffracted order beams as the beam is scanned over the diffraction pattern, deviations of said information signals from a predetermined reference being a measure of the change in line parameters comprising essentially the lateral dimensions of the lines, the thickness of the lines, and the profile of the edge of the lines of the diffraction pattern.

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