| 摘要 |
PURPOSE:To detect a defect to some extent of one picture element even when a positioning error is present by comparing a gradient vector obtained from the density distribution of the image of a pattern to be inspected and the density distribution of the image of a reference pattern. CONSTITUTION:When respective density distributions of an image 11 of a multi- value pattern to be inspected and an image 12 of the multi-value reference pattern are f(xi,yj) and g(xi,yj), respective gradient vectors A and B are calculated from these density distributions. At such a time, considering the positioning error of both patterns, a gradient vector A(xi,yj), B(xi,yj) and an adjoining gradient vector B(xk,yl) are compared, the minimum value at the range of k=i-1, i,i+1,l=j-1, j,j+1 of an absolute value ¦B(xk,yl)-A(xi,yj)¦ of the difference in the vectors is made into C(xi,yj), and when the picture element is present which comes to be C(xi,yj)>=V to a set threshold V, it is decided that the defect is present at the pattern to be inspected. |
