PATTERN BINARIZATION METHOD AND ITS DEVICE

摘要

PURPOSE:To automate the test of the external appearance of a wafer pattern by finding out the maximum grade of histograms of pictures corresponding to two circuit patterns and finding out the brightness coinciding with the frequency of brightness forming the grade to obtain a binarization threshold related to the brightness. CONSTITUTION:An output from a linear image sensor is inputted to a histogram forming circuit 14 of a binarization threshold detecting circuit to form its histogram and the histogram is smoothed by a smoothing circuit 15 to remove noise. A maximum value/minimum value detecting circuit 16 detects maximum values f(Zmax1), f(Zmax2) and a minimum value f(Zmin) and a grade detecting circuit 17 detects the maximum grade among the f(Zmax1), f(Zmax2) and f(Zmin) to determine f(Zk)=C from the frequency of the maximum brightness Zk. An intersecting point detecting circuit 18 finds out the brightness Z1-Z4 finding out an intersecting point with the histogram to find out primary coupling with constants C1-C4 determined by a threshold determining circuit 19 and determine the threshold Th.