Methods and systems for measuring periodic structures using multi-angle X-ray reflectance scatterometry (XRS)

A method to measure a sample using an X-ray reflectance scatterometry, the method comprising:

• impinging an incident low energy X-ray beam having an energy of 1keV or less on a sample having a periodic structure to generate a scattered X-ray beam, wherein the incident low energy X-ray beam is converging in an incidence and azimuth planes thereby providing simultaneously a plurality of incident angles and a plurality of azimuthal angles and having a range of incident angles that is greater than a range of azimuthal angles;
• and
• collecting at least a portion of the scattered X-ray beam using a two-dimensional detector to simultaneously sample a scattered signal intensity of the at least the portion of the scattered X-ray beam that is scattered from the range of incident angles and the range of azimuthal angles.