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Automated method for determining several critical dimension properties from scanning electron microscope by using several tilted beam or sample scans

  • US 6,472,662 B1
  • Filed: 08/30/2000
  • Issued: 10/29/2002
  • Est. Priority Date: 08/30/2000
  • Status: Expired due to Fees
First Claim
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1. A method for extracting structural information on a workpiece by having a scanning electron microscope (SEM) scan the workpiece to acquire waveform information at a plurality of tilt angles, wherein the process of extracting the structural information extends beyond the resolution of the SEM, the method comprising the steps of:

  • (a) setting an SEM beam to a first/next tilt angle;

    (b) scanning across a region of the workpiece at the tilt angle to acquire a waveform;

    (c) analyzing the waveform to extract a Distance between Extremal Slope Locations (DESL) value for each edge of interest;

    (d) determining whether there are two acceptable DESL values for each structural edge by comparing each DESL value to a DESL threshold value;

    wherein, if there are at least two of said DESL values that arc greater than said DESL threshold value, then sufficient information has been obtained, and else, returning to step a), and (e) determining the height and the sidewall angle of the structure on the workpiece, wherein when both of said DESL values are greater than at least 1.5 times the DESL threshold value, then a geometrical analysis extracts the height and sidewall angle of the structure on the workpiece, and when either of said two DESL values is smaller than at least 1.5 times said DESL threshold value, then the geometrical analysis is modified to include limitations in the resolution of the SEM.

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