Small-angle x-ray scatterometry

A method for evaluating an array of high aspect ratio (HAR) structures on a sample includes illuminating the sample with an x-ray beam along a first axis parallel to within two degrees to the HAR structures in the array and sensing a first pattern of small angle x-ray scattering (SAXS) scattered from the sample while illuminating the sample along the first axis. The sample is illuminated with the x-ray beam along a second axis that is oblique to the HAR structures in the array, and a second pattern of the SAXS scattered from the sample is sensed while illuminating the sample along the second axis. Information is extracted with respect to the HAR structures based on the first and second patterns.