×

Automated direct patterned wafer inspection

  • US 5,513,275 A
  • Filed: 06/09/1994
  • Issued: 04/30/1996
  • Est. Priority Date: 01/12/1993
  • Status: Expired due to Fees
First Claim
Patent Images

1. A method of inspecting a two dimensional periodic image of a semiconductor device and a photomask as used in semiconductor device fabrication for irregularities and defects comprising the steps ofa) estimating repetition periods of patterns in horizontal and vertical directions in said image,b) extracting a building block of said image based on said repetition periods including obtaining a sub-pixel weighted sum of repeated patterns throughout said image, andc) subtracting shifted versions of said building block from said image to locate defects and irregularities.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×