Small angle x-ray scattering metrology for sidewall angle and cross section of nanometer scale line gratings

High-volume fabrication of nanostructures, which required nondestructive metrologies capable of measuring not only the pattern shape profile but also the pattern size, was discussed. A small angle x-ray scattering (SAXS) based technique has the capability of characterizing the pattern width and average pitch size to subnanometer precision. A modeling-free protocol to extract cross-section information was also reported. Reciprocal space positions and diffraction peak intensities were measured while the sample was rotated around the axis perpendicular to the grating direction. It was found that the linear extrapolations of peak positions in reciprocal space allowed a precise determination of both the pattern height and the sidewall angle.