Method and apparatus for pattern inspection

Abstract

According to the present invention, for a pattern inspection apparatus that compares images in corresponding areas of two patterns that are identical and that determines an unmatched portion between the images is a defect, a plurality of detection systems and a plurality of corresponding image comparison methods are provided. With this configuration, the affect of uneven brightnesses for a pattern that occurs due to differences in film thicknesses can be reduced, a highly sensitive pattern inspection can be performed, a variety of defects can be revealed, and the pattern inspection apparatus can be applied for processing performed within a wide range. Furthermore, the pattern inspection apparatus also includes a unit for converting the tone of image signals of comparison images for a plurality of different processing units, and when a difference in brightness occurs in the same pattern of the images, a defect can be correctly detected.

1 . A pattern inspection method comprising:
 an irradiating step of irradiating a sample under a plurality of optical conditions, using information of the sample and information of a defect of an inspection object;   a detecting step of detecting a plurality of scattered or reflected lights from the sample irradiated in the irradiating step under the plurality of optical conditions, respectively, and processing the detected scattered lights to thereby obtain a plurality of images; and   a processing step of processing the plurality of images respectively corresponding to the plurality of optical conditions obtained in the detecting step to thereby obtain information of the plurality of images.   
     
     
         2 . The pattern inspection method according to  claim 1 , further comprising:
 a displaying step of displaying the information of the plurality of images obtained in the processing step.   
     
     
         3 . The pattern inspection method according to  claim 1 , further comprising:
 a selecting step of selecting at least one of the plurality of optical conditions based on the information of the plurality of images obtained in the processing step.   
     
     
         4 . The pattern inspection method according to  claim 1 , wherein the information of the sample used in the irradiating step is obtained by a step of processing of the sample or a target area of the sample notified in the inspection. 
     
     
         5 . The pattern inspection method according to  claim 1 , wherein the information of a defect used in the irradiating step is a coordinate or a kind of a defect desired to be detected in the inspection. 
     
     
         6 . The pattern inspection method according to  claim 2 , wherein the information of the plurality of images used in the displaying step is at least one of contrasts, density differences, luminance distributions and signal-to-noise ratios (S/Ns) of the plurality of images. 
     
     
         7 . The pattern inspection method according to  claim 3 , wherein the at least one of the plurality of optical conditions is selected in the selecting step by taking into consideration a detection function of an image comparison method or an image categorizing method corresponding to the plurality of optical conditions. 
     
     
         8 . The pattern inspection method according to  claim 7 , wherein said detection function comprises detection efficiency. 
     
     
         9 . A pattern inspection apparatus comprising:
 an optical illumination system for irradiating a sample under a plurality of optical conditions, using information of the sample and information of a defect of an inspection object;   a detector for detecting a plurality of scattered or reflected lights from the sample by the optical illumination system under the plurality of optical conditions, respectively, and processing the detected scattered lights to thereby obtain a plurality of images; and   a processor for processing the plurality of images respectively corresponding to the plurality of optical conditions obtained by the detector to thereby obtain information of the plurality of images.   
     
     
         10 . The pattern apparatus according to  claim 9 , further comprising:
 a displaying device displaying the information of the plurality of images obtained by the processor step.   
     
     
         11 . The pattern inspection apparatus according to  claim 9 , further comprising:
 a selector for selecting at least one of the plurality of optical conditions based on the information of the plurality of images obtained by the processor step.   
     
     
         12 . The pattern inspection apparatus according to  claim 9 , wherein the information of the sample used by the optical illumination system is obtained by processing of the sample or a target area of the sample notified in the inspection. 
     
     
         13 . The pattern inspection apparatus according to  claim 9 , wherein the information of a defect used by the optical illumination system is a coordinate or a kind of a defect desired to be detected in the inspection. 
     
     
         14 . The pattern inspection apparatus according to  claim 10 , wherein the information of the plurality of images used by the displaying device is at least one of contrasts, density differences, luminance distributions and signal-to-noise ratios (S/Ns) of the plurality of images. 
     
     
         15 . The pattern inspection apparatus according to  claim 11 , wherein the at least one of the plurality of optical conditions is selected by the selector by taking into consideration a detection function of an image comparison method or an image categorizing method corresponding to the plurality of optical conditions. 
     
     
         16 . The pattern inspection apparatus according to  claim 15 , wherein said detection function comprises detection efficiency.