Method and its apparatus for inspecting a pattern

Abstract

In a pattern inspecting apparatus, images of places which can be expected to be the same pattern are compared with one another. However, a comparison of images obtained by different stage scans and the occurrence of a place capable of being inspected only once lead to a deterioration in the performance of detecting various error defects and an area incapable of being inspected, respectively. For solving this problem, defects detected in a high sensitivity condition are regarded as defect candidates and a critical threshold value, used as a boundary to detect a smaller value as a defect, of a defect candidate portion is obtained by an image processing circuit or an image of the defect candidate portion is obtained by processing with software. Further, the critical threshold value thus obtained is compared with plural threshold values, thereby permitting plural inspection results to be obtained in a single inspection.

1 . A pattern inspecting method comprising the steps of: 
 picking up an image of a substrate with a pattern formed thereon;    subjecting a signal obtained by the image pick-up to A/D conversion to afford a digital signal; 
 storing images of first defect candidates together with information on feature quantities of the images of the first defect candidates;  
   extracting second defect candidates using at least the stored information of feature quantities of the images of the first defect candidates; and    displaying on a screen a state of distribution of the extracted second defect candidates on the substrate.