Image contrast in X-ray topography imaging for defect inspection

A system for X-ray topography, the system comprising:

• a source assembly, which is configured to direct at least an X-ray beam to impinge, at an angle, on a first surface of a sample, wherein the X-ray beam is divergent when impinging on the first surface;
• a detector assembly, which is configured to detect the X-ray beam that had entered the sample at the first surface, diffracted while passing through the sample and exited the sample at a second surface that is opposite to the first surface, and to produce an electrical signal in response to the detected X-ray beam;
• a motion assembly, which is configured to move the source assembly relative to the sample;
• and
• a processor, which is configured:
• (i) to control the motion assembly, in response to variations in an angle of diffraction of the X-ray beam from the sample, to compensate for shifts in a position at which the X-ray beam irradiates the detector assembly, so as to increase a signal-to-background ratio (SBR) of the electrical signal produced by the detector assembly, and (ii) to detect one or more defects in the sample based on the electrical signal.