Patent ID: 6753542
Filing Date: 2004-06-22
Classification: G01N

Abstract:
A defect detection apparatus comprising: an illuminating unit which irradiates an inspection object with illuminating light; and an image pickup unit which picks up an image of a diffracted light from the inspection object to perform defect inspection of the inspection object from image data picked up by the image pickup unit, the apparatus further comprising:a diffraction angle calculation unit to obtain an angle of incidence of the illuminating light with respect to the inspection object, which is optimum for picking up the image of the diffracted light, based on design information of the inspection object; an illuminating angle control unit which changes an angle of incidence of the illuminating unit with respect to the inspection object; a luminance distribution calculation unit which obtains a luminance distribution with respect to the angle of incidence from the image data of the image pickup unit obtained by varying the angle of incidence of the illuminating unit with respect to the inspection object by the illuminating angle control unit; and an illuminating setting unit to compare the luminance distribution obtained by the luminance distribution calculation unit with the angle of incidence calculated by the diffraction angle calculation unit and to set the illuminating unit to the angle of incidence corresponding to a luminance peak in the luminance distribution which is closest to the calculated angle of incidence.