Determination of interfacial roughness correlation in W/C multilayer films: Comparison using soft and hard x-ray diffraction

Interfacial roughness correlation in W/C multilayer films with periods of 23, 30, and 37 Å is examined with x-ray diffraction using λ in the 10–13 Å range and λ=1.54 Å. Transverse scans through multilayer Bragg reflections are analyzed to determine the magnitude and lateral correlation length of the component of interfacial roughness that is perfectly correlated through the multilayer stack. The results are independent of wavelength, even though hard x rays sample much more deeply into the film, indicating that interfacial roughness is not changing through these films.