Surface inspecting apparatus and surface inspecting method

Abstract

There is provided a surface inspecting apparatus capable of performing inspection at higher speed and with higher accuracy. A surface inspecting apparatus ( 1 ) is provided with an illumination optical system ( 30 ) for irradiating linearly polarized light to a surface of a wafer ( 10 ) under a plurality of inspection conditions; an imaging optical system ( 40 ) for capturing an image of the wafer ( 10 ) formed by polarization components having an oscillation direction that is different from that of the linearly polarized light as part of reflected light from the surface of the wafer ( 10 ) irradiated by the linearly polarized light under the plurality of inspection conditions; and an image-processing apparatus ( 50 ) for extracting for individual pixels an image having the smallest signal intensity from among images of the wafer ( 10 ) captured under the plurality of inspection conditions by the imaging optical system ( 40 ), and for inspecting for the presence of defects in a repeated pattern of the wafer ( 10 ) on the basis of an inspection image of the wafer ( 10 ) generated by connecting each of the extracted pixels.

1 . A surface inspection apparatus comprising:
 an illumination unit for irradiating linearly polarized light onto a surface of an inspected substrate having a predetermined repeating pattern;   an imaging unit for capturing an image of the inspected substrate formed by polarization components having an oscillation direction that is different from that of the linearly polarized light as part of the reflected light from the surface of the inspected substrate irradiated by the linearly polarized light;   a setting unit for setting a plurality of conditions in at least one of an illumination condition in the illumination unit and an imaging condition in the imaging unit; and   an information processing unit for calculating a signal intensity for each portion of each of a plurality of images of the inspected substrate photographed by the imaging unit under the plurality of inspection conditions, comparing the signal intensity of the same portions in the plurality of images of the inspected substrate, and generating inspection information of the inspected substrate from information of the portions having the smallest signal intensity.   
     
     
         2 . The surface inspection apparatus according to  claim 1 , wherein the signal intensity is a signal intensity standardized according to the signal intensity from a normal repeating pattern. 
     
     
         3 . The surface inspection apparatus according to  claim 1 , comprising a display unit for generating an inspection image on the basis of the inspection information generated by the information processing unit and visibly displaying the inspection image. 
     
     
         4 . The surface inspection apparatus according to  claim 1 , comprising an inspection unit for inspecting for the presence of a defect in the repeating pattern; wherein
 the inspection unit is configured so as to inspect for the presence of a defect in the repeating pattern by comparing the inspection information and predetermined reference information;   the illumination unit irradiates linearly polarized light onto a surface of a reference substrate as a reference for the inspection under the plurality of inspection conditions, and the imaging unit captures an image of the reference substrate formed by polarization components having an oscillation direction that is different from that of the linearly polarized light as part of the reflected light from the surface of the reference substrate irradiated by the linearly polarized light; and   the information processing unit calculates a signal intensity for each portion of each of the plurality of images of the reference substrate photographed by the imaging unit under the plurality of inspection conditions, compares the signal intensity of the same portions in the plurality of images of the reference substrate, extracts a portion having the smallest signal intensity for each of the portions, and generates the reference information from information of the extracted portion.   
     
     
         5 . The surface inspection apparatus according to  claim 1 , wherein the inspection condition set by the setting unit is an angle formed by the oscillation direction of the linearly polarized light and the oscillation direction of the polarization components. 
     
     
         6 . The surface inspection apparatus according to  claim 1 , wherein the inspection condition set by the setting unit is an angle formed by the repetition direction of the repeating pattern and the oscillation direction of the linearly polarized light on the surface of the inspected substrate. 
     
     
         7 . The surface inspection apparatus according to  claim 1 , wherein the inspection condition set by the setting unit is the wavelength of the linearly polarized light. 
     
     
         8 . A surface inspection method comprising:
 a first step of setting an inspection condition;   a second step of irradiating linearly polarized light to a surface of an inspected substrate having a predetermined repeating pattern;   a third step of capturing an image of the inspected substrate formed by polarization components having an oscillation direction that is different from that of the linearly polarized light as part of the reflected light from the surface of the inspected substrate irradiated by the linearly polarized light; and   a fourth step of calculating a signal intensity for each portion of each of a plurality of images of the inspected substrate photographed under the plurality of inspection conditions in the third step, comparing the signal intensity of the same portions in the plurality of images of the inspected substrate, and generating inspection information of the inspected substrate from information of the portions having the smallest signal intensity.   
     
     
         9 . The surface inspection method according to  claim 8 , comprising a fifth step of generating an inspection image on the basis of the inspection information generated in the fourth step and visibly displaying the inspection image. 
     
     
         10 . The surface inspection method according to  claim 8 , comprising:
 a sixth step of inspecting for the presence of a defect in the repeating pattern on the basis of the inspection information generated in the fourth step,   the sixth step comprising inspecting for the presence of a defect in the repeating pattern by comparing the inspection information and predetermined reference information;   a seventh step of irradiating linearly polarized light onto a surface of a reference substrate as a reference for the inspection under the plurality of inspection conditions;   an eighth step of capturing an image of the reference substrate formed by polarization components having an oscillation direction that is different from that of the linearly polarized light as part of the reflected light from the surface of the reference substrate irradiated by the linearly polarized light under the plurality of inspection conditions; and   a ninth step of calculating a signal intensity for each portion of each of the plurality of images of the reference substrate photographed under the plurality of inspection conditions in the eighth step, comparing the signal intensity of the same portions in the plurality of images of the reference substrate to extract the portions having the smallest signal intensity for each of the portions, and generating the reference information from information of the extracted portions.   
     
     
         11 . The surface inspection method according to  claim 8 , wherein the inspection condition set in the first step is an angle formed by the oscillation direction of the linearly polarized light and the oscillation direction of the polarization components. 
     
     
         12 . The surface inspection method according to  claim 8 , wherein the inspection condition set in the first step is an angle formed by the repetition direction of the repeating pattern and the oscillation direction of the linearly polarized light on the surface of the inspected substrate. 
     
     
         13 . The surface inspection method according to  claim 8 , wherein the inspection condition set in the first step is the wavelength of the linearly polarized light.