EBeam Inspection Method

Abstract

An image is obtained by using a charged particle beam, and a design layout information is generated to select patterns of interest. Grey levels among patterns can be compared with each other to identify abnormal, or grey levels within one pattern can be compared to a determined threshold grey level to identify abnormal.

1 - 20 . (canceled) 
     
     
         21 . An inspection method, comprising:
 scanning a sample with a charged particle beam to obtain an image comprising pixels with grey levels;   aligning the image to design layout information to identify a plurality of repeated patterns on the image, the plurality of repeated patterns corresponding to a feature repeatedly formed on the sample;   performing a comparison of a grey level of a first repeated pattern of the plurality of repeated patterns with one or more other grey levels of the first repeated pattern; and   determining, based on the comparison, an abnormality of the first repeated pattern of the plurality of repeated patterns.   
     
     
         22 . The method according to  claim 21 , wherein performing the comparison of the grey level of the first repeated pattern of the plurality of repeated patterns with the one or more other grey levels of the first repeated pattern comprises:
 determining a threshold grey level based on the grey levels of the first repeated pattern.   
     
     
         23 . The method according to  claim 22 , wherein determining, based on the comparison, an abnormality of the first repeated pattern comprises:
 identifying that a pixel of the first repeated pattern corresponds to a defect on the sample in response to a grey level of the pixel being determined an outlier from the threshold grey level.   
     
     
         24 . The method according to  claim 21 , wherein the plurality of repeated patterns includes a first pattern and a second pattern, and the method further comprises:
 comparing grey levels of the first pattern to grey levels of the second pattern; and   determining an abnormality of the first pattern based on the comparison of the grey levels of the first pattern to the grey levels of the second pattern.   
     
     
         25 . The method according to  claim 24 , wherein determining an abnormality of the first pattern based on the comparison of the grey levels of the first pattern to the grey levels of the second pattern comprises:
 determining that the first pattern includes a defect if the grey level of at least one pixel of the first pattern is an outlier from the grey levels of the second pattern.   
     
     
         26 . The method according to  claim 25 , wherein the defect is a voltage contrast defect. 
     
     
         27 . The method according to  claim 21 , wherein the charged particle beam is an electron beam generated by a scanning electron microscope. 
     
     
         28 . A defect inspection system comprising:
 an inspection tool for inspecting a sample;   a memory storing instructions; and   one or more processors configured to execute the instructions to cause the defect inspection system to:
 scan the sample with a charged particle beam to obtain an image comprising pixels with grey levels; 
 align the image to design layout information to identify a plurality of repeated patterns on the image, the plurality of repeated patterns corresponding to a feature repeatedly formed on the sample; 
 perform a comparison of a grey level of a first repeated pattern of the plurality of repeated patterns with one or more other grey levels of the first repeated pattern; and 
 determine, based on the comparison, an abnormality of the first repeated pattern of the plurality of repeated patterns. 
   
     
     
         29 . The defect inspection system according to  claim 28 , wherein in performing the comparison of the grey level of the first repeated pattern of the plurality of repeated patterns with the one or more other grey levels of the first repeated pattern, the one or more processors are configured to execute the instructions to cause the defect inspection system to:
 determine a threshold grey level based on the grey levels of the first repeated pattern.   
     
     
         30 . The defect inspection system according to  claim 29 , wherein in determining, based on the comparison, an abnormality of the first repeated pattern, the one or more processors are configured to execute the instructions to cause the defect inspection system to:
 identify that a pixel of the first repeated pattern corresponds to a defect on the sample in response to a grey level of the pixel being determined an outlier from the threshold grey level.   
     
     
         31 . The defect inspection system according to  claim 28 , wherein the plurality of repeated patterns includes a first pattern and a second pattern, and the one or more processors are further configured to execute the instructions to cause the defect inspection system to:
 compare grey levels of the first pattern to grey levels of the second pattern; and   determine an abnormality of the first pattern based on the comparison of the grey levels of the first pattern to the grey levels of the second pattern.   
     
     
         32 . The defect inspection system according to  claim 31 , wherein in determining an abnormality of the first pattern based on the comparison of the grey levels of the first pattern to the grey levels of the second pattern, the one or more processors are configured to execute the instructions to cause the defect inspection system to:
 determine that the first pattern includes a defect if the grey level of at least one pixel of the first pattern is an outlier from the grey levels of the second pattern.   
     
     
         33 . The defect inspection system according to  claim 32 , wherein the defect is a voltage contrast defect. 
     
     
         34 . The defect inspection system according to  claim 28 , wherein the charged particle beam is an electron beam generated by a scanning electron microscope. 
     
     
         35 . A non-transitory computer-readable medium storing a set of instructions that is executable by one or more processors of one or more devices to cause the one or more devices to perform a method comprising:
 receiving an image generated by scanning a sample with a charged particle beam, the image comprising pixels with grey levels;   aligning the image to design layout information to identify a plurality of repeated patterns on the image, the plurality of repeated patterns corresponding to a feature repeatedly formed on the sample;   performing a comparison of a grey level of a first repeated pattern of the plurality of repeated patterns with one or more other grey levels of the first repeated pattern; and   determining, based on the comparison, an abnormality of the first repeated pattern of the plurality of repeated patterns.   
     
     
         36 . The non-transitory computer-readable medium according to  claim 35 , wherein in performing the comparison of the grey level of the first repeated pattern of the plurality of repeated patterns with the one or more other grey levels of the first repeated pattern, the execution of the set of instructions further causes the one or more devices to perform:
 determining a threshold grey level based on the grey levels of the first repeated pattern.   
     
     
         37 . The non-transitory computer-readable medium according to  claim 36 , wherein in determining, based on the comparison, an abnormality of the first repeated pattern, the execution of the set of instructions further causes the one or more devices to perform:
 identifying that a pixel of the first repeated pattern corresponds to a defect on the sample in response to a grey level of the pixel being determined an outlier from the threshold grey level.   
     
     
         38 . The non-transitory computer-readable medium according to  claim 35 , wherein the plurality of repeated patterns includes a first pattern and a second pattern, and the execution of the set of instructions further causes the one or more devices to perform:
 comparing grey levels of the first pattern to grey levels of the second pattern; and   determining an abnormality of the first pattern based on the comparison of the grey levels of the first pattern to the grey levels of the second pattern.   
     
     
         39 . The non-transitory computer-readable medium according to  claim 38 , wherein in determining an abnormality of the first pattern based on the comparison of the grey levels of the first pattern to the grey levels of the second pattern, the execution of the set of instructions further causes the one or more devices to perform:
 determining that the first pattern includes a defect if the grey level of at least one pixel of the first pattern is an outlier from the grey levels of the second pattern.   
     
     
         40 . The non-transitory computer-readable medium according to  claim 39 , wherein the defect is a voltage contrast defect.