X-ray based measurements in patterned structure

A measurement system for use in X-ray based measurements on patterned structures of a sample, the system comprising:

• an illumination unit configured to illuminate the patterned structures, by an incident X-ray radiation;
• a detection unit that is configured to detect an X-ray radiation response from the patterned structures;
• a computer system that is configured to process measured signals corresponding to the X-ray radiation response of the patterned structures;
• wherein the measured signals are indicative of a) an angular span of plurality of diffraction orders that were scattered from the patterned structure, and (b) background signals;
• a filling module that is configured to deduce the background signals to provide deducted background signals;
• wherein the compute system is further configured to:
• subtract from measured signals within the angular span, the background signals to provide background removed signals that are substantially free of the background signals, and
• determine, based on the background removed signals, one or more parameters of the patterned structure.