| 摘要 |
PURPOSE:To enable a defect of the size of the order of one pixel to be easily detected by comparing plane configurations with one another in the area of a number of pixels centered on a gradient vector obtained from the density distributions of the images of a pattern to be inspected and a reference pattern. CONSTITUTION:The image 11 of a pattern to be inspected by transmitted light is expressed by a multivalued system and it is assumed that spatial position coordinates are (x) and (y) and the density distribution of a pixel (xi, yj) is f(xi, yj). Then, a gradient vector A corresponding to grad (f) obtained from the image 11 is obtained. The gradient vector of a reference pattern is obtained in the same manner as above and both the vectors are compared with each other. That is, total nine vectors composed of a vector corresponding to the pixel (xi, yj) and vectors corresponding to eight surrounding pixels are compared with one another on a one-to-one basis and the means C of the absolute values of difference vectors is obtained. Further, nine kinds of the means C are obtained by comparing planes adjacent to the pixel (xi, yj) and deviated by + or -1 pixel therefrom with one another and a given threshold value V is set to the minimum value of the nine kinds of the means C. When the pixel wherein C(xi, yj)>=V holds is present, it is decided that the pattern being inspected has a defect. |
