Characterization of interface roughness in W/Si multilayers by high resolution diffuse X-ray scattering

We present the first high resolution measurements of diffuse scattering from interface roughness in multilayers. The example of an amorphous W/Si multilayer is taken to illustrate the technique and the approach followed in the data evaluation. The scattering intensity under grazing incidence and exit has been recorded with an Si(220) analyzer crystal to improve the resolution perpendicular to the plane of reflection. The structure factor of the interfaces is determined over a range of more than three decades in parallel momentum transfer, while covering up to five Bragg sheets simultaneously along the exit angle. Hence, the interface roughness is probed on lateral length scales between a few Angstrom and more than one mu m.