Non-destructive sub-nanometer evaluation of sidewall coverage in deep holes by small-angle x-ray scattering

We have applied a transmission small-angle X-ray scattering (T-SAXS) technique to determine thickness profiles of metal deposited on the sidewall of deep holes. By using both the high-Q range and high-Q resolution T-SAXS data, we have successfully determined the metal sidewall thickness profiles, which are only about 2 nm thickness, and the hole CD profile, which is about 60 nm in diameter, simultaneously without any prior measurements of the undeposited sample. Comparing the T-SAXS results with scanning transmission electron microscope (STEM) images, it was realized that the CD and the metal sidewall thickness profiles were in good agreement with the two kinds of metrology. It was further confirmed that the metal sidewall thickness profiles could be measured with sub-nanometer accuracy.