Inspection method for semiconductor wafer and apparatus for reviewing defects

Abstract

An object of the present invention is to provide a suitable method of observing a wafer edge by using an electron microscope. The electron microscope includes a column which can take an image in being tilted, and thus allows a wafer edge to be observed from an oblique direction.

1 - 5 . (canceled) 
     
     
         6 . A defect review apparatus comprising:
 a sample stage that holds a sample;   a column comprising an electron optical system that directs an electron beam onto the sample;   an image acquisition unit that acquires a first image and a second image based on a signal generated as the electron beam hits the sample; and   an image calculation unit that determines, based on the first image, whether or not a defect of a pre-specified type is present,   wherein if it is determined by the image calculation unit that a defect of the pre-specified type is present, the electron optical system directs an electron beam onto the sample at an angle that differs from the angle formed between the electron beam and a surface of the sample when the first image was acquired, and the image acquisition unit acquires the second image based on a signal generated from the sample.   
     
     
         7 . The defect review apparatus according to  claim 6 , wherein the pre-specified type comprises a peeling mode. 
     
     
         8 . The defect review apparatus according to  claim 6 , further comprising a mechanism that makes the angle of the column relative to the sample surface variable. 
     
     
         9 . The defect review apparatus according to  claim 6 , wherein the sample stage comprises a tilting mechanism. 
     
     
         10 . The defect review apparatus according to  claim 6 , wherein the electron optical system comprises a deflection control mechanism that deflects the electron beam so as to make the electron beam be incident at an angle relative to a normal to the sample. 
     
     
         11 . The defect review apparatus according to  claim 6 , further comprising a second electron optical system that directs an electron beam onto the sample, wherein:
 one of the electron optical system and the second electron optical system directs the electron beam in a normal direction to the sample surface, and the other directs the electron beam at an angle that differs from an angle at which the one is installed, and   the image acquisition unit acquires the second image based on an output signal of the other of the electron optical system and the second electron optical system.   
     
     
         12 . The defect review apparatus according to  claim 6 , wherein movement of the sample stage is controllable in a rotational direction. 
     
     
         13 . The defect review apparatus according to  claim 6 , further comprising an input unit that allows the angle formed between the electron beam and the sample surface to be set. 
     
     
         14 . The defect review apparatus according to  claim 6 , wherein the image acquisition unit allows an observation area with respect to the sample to be set. 
     
     
         15 . A defect review apparatus comprising:
 a sample stage that holds a sample and moves;   an optical microscope capable of observing a peripheral portion of the sample;   a calculation unit that determines, based on an observation result of the optical microscope, whether or not a defect is present in the peripheral portion; and   an electron microscope that carries out observation by directing an electron beam to a location of a defect determined by the calculation unit,   wherein the electron beam is incident on the sample from a direction that is slanted relative to a surface of the sample.   
     
     
         16 . The defect review apparatus according to  claim 15 , wherein:
 the calculation unit determines, based on the observation result of the optical microscope, whether or not a defect of a pre-specified type is present, and   if it is determined by the calculation unit that a defect of the pre-specified type is present at the peripheral portion, observation is carried out using the electron microscope.   
     
     
         17 . A defect review apparatus comprising:
 a sample stage that holds a sample and moves;   an electron optical system that directs an electron beam onto the sample;   an image acquisition unit that acquires an image based on a signal generated as the electron beam hits the sample; and   an image calculation unit that determines, based on the image, whether or not a defect of a pre-specified type is present,   wherein if it is determined by the image calculation unit that a defect of the pre-specified type is present, the electron optical system causes the electron beam to be incident in a slanted manner relative to a surface of the sample, and the image acquisition unit re-acquires an image at a position where the defect is located.   
     
     
         18 . An electron microscope comprising:
 a sample stage capable of rotational movement while holding a sample;   an electron optical system capable of scanning a peripheral portion of the sample with an electron beam;   a control unit that controls the scanning of the electron beam;   a detector that detects a signal generated from the sample as a result of the scanning of the electron beam;   an image acquisition unit that acquires an image based on a signal from the detector; and   a display unit that displays the image,   wherein the control unit rotates a direction of the scanning, or an imaging region, in accordance with a rotation angle of the sample stage.   
     
     
         19 . The electron microscope according to  claim 18 , further comprising a mechanism that causes the electron beam to be incident at an angle relative to a normal to a surface of the sample.