Surface inspection with variable digital filtering

Abstract

A semiconductor wafer, which is an inspection object, is stuck by vacuum on a chuck and this chuck is mounted on an inspection object movement stage consisting of a rotational stage and a translational stage, located on a Z-stage. The rotational stage provides a rotational movement and the translational stage provides a translational movement. And when a foreign particle or a defect on an inspection object surface is detected, the parameter of digital filtering is dynamically changed during inspection, and the foreign particle or the defect is differentiated using the result after removing a low frequency fluctuation component to be a noise component.

1 . A surface inspection apparatus for detecting a foreign particle or a defect present on an inspection object surface or inside the proximity of the surface, comprising:
 an inspection object movement stage having a rotational movement unit and a translational movement unit configured so as to be able to scan said inspection object at an approximately constant rotational angular speed;   a laser beam source;   an illumination unit irradiating an laser beam emitted from said laser beam source on an illumination spot of a predetermined size on the inspection object surface;   a scattered/diffracted/reflected light detection unit, wherein an irradiating light detects a scattered/diffracted/reflected light at said illumination spot and converts to an electric signal;   an A/D converter for conversion of said electric signal into digital data;   a particle diameter calculation device for calculating a size of the foreign particle or the defect from the digital data obtained by said A/D conversion;   wherein said A/D conversion unit executes sampling of said electric signal at approximately constant sampling time intervals, and said particle diameter calculation device executes detection of the foreign particle/defect by using a result of a removal treatment of an undesired low frequency fluctuation component on the digital data obtained by said A/D converter.   
   
   
       2 - 18 . (canceled)