Evaluating semiconductor wafers for pitch walking and/or epitaxial merge

Evaluating a semiconductor wafer may include recording a first intensity of a reflection of an X-ray beam onto a test area on a substrate of the semiconductor wafer at a detector as the X-ray beam is projected substantially perpendicular to a length of expected, periodic structures in the test area and at an angle defined between the X-ray beam and a surface of the test area. Second intensities may be recorded of the reflection of the X-ray beam onto the test area as the X-ray beam is projected onto the test area at increments from the angle. Intensity peaks in the recordings of the first and second intensities are identified and, based on positions of the intensity peaks relative to the test area, a peak spacing between the plurality of expected, periodic structures is determined indicative of pitch walking or epitaxial merge.