CONTAMINANT DETECTION METROLOGY SYSTEM, LITHOGRAPHIC APPARATUS, AND METHODS THEREOF

摘要

A system includes an illumination system, a detector, and a comparator. The illumination system includes a radiation source and a spatial light modulator. The radiation source generates a beam of radiation. The spatial light modulator directs the beam toward a surface of an object and adjusts a spatial intensity distribution of the beam at the surface. The detector receives radiation scattered at the surface and by a structure near the surface. The detector generates a detection signal based on the received radiation. The comparator receives the detection signal, generates a first image based on the detection signal, and distinguishes between a spurious signal and a signal corresponding to a presence of a foreign particle on the surface based on the first image and the adjusted spatial intensity distribution.