System for optical inspection of a substrate using same or different wavelengths

A system for optical inspection of a substrate, the system comprising:

• an illumination device comprising a light source for generating at least one incident light beam exhibiting at least a first wavelength directed onto an exposed surface of the substrate and defining an inspection area of the substrate, defects present on, or close to, the surface of the substrate provoking an emission of radiation at the first wavelength and/or radiation exhibiting at least a second wavelength different from the at least first wavelength;
• a support to receive the substrate and to position the substrate relative to the illumination device, the support and the light source being movable relative to each other according to a scanning direction;
• and
• a detection device comprising a collector for collecting at least a portion of the radiation at the first wavelength and/or at the at least a second wavelength originating from a detection area of the substrate, and a detector optically associated with the collector, the detector including a sensing surface for capturing the collected radiation, the detection area being the area of the substrate that encompasses all the emitted radiation collected by the collector and captured by the sensing surface of the detector at a given point in time, the detection device providing a measurement signal representing a variation in intensity of the collected radiation as the substrate is moved along the scanning direction;
• wherein the system is in a dark field configuration ensuring that the specular reflections of the incident light beam on the substrate are not collected by the collector and is configured to position the inspection area ahead of at least a portion of the detection area, with respect to the scanning direction, while the inspection area scans the exposed surface of the substrate, such that a part of the substrate having left the inspection area due to a relative movement of the support and the light source will remain in the detection area for a period of time.