Patent ID: 7728294

Claim:
A semiconductor wafer inspection tool comprising: an electron source which emits primary electrons; an irradiation optical system which irradiates the primary electrons from the electron source onto an object; a scanning section which scans irradiation positions of the primary electrons in an X direction and in a Y direction; a charge control electrode which for generating an electric field distribution to charge the objective positively or negatively; a sensor which detects the secondary electrons or the reflected electrons through the charge control electrode and outputs a detection signal; an image processor which converts the detection signal from the sensor to a detected image, compares the detected image with a predetermined reference image and judges defects; an overall control section which sets a voltage to be applied to the charge control electrode according to an inspection condition selected from recipe information describing a plurality of inspection conditions for each object; and a distance controller configured to adjust a distance between the object and the charge control electrode depending on mode type of positively charging the object and negatively charging the object.