Asymmetric extreme ultraviolet scattering from sputter-deposited multilayers

Asymmetric scattering of extreme ultraviolet Light is observed from Mo/Si multilayers at normal incidence. The observed asymmetry is shown to depend on the geometry of the multilayer film deposition. However, atomic force microscopy (AFM) measurements of the top surface were isotropic, and there was no indication of columnar film growth either in the AFM or in TEM cross-sectional measurements. The scattering asymmetry is instead found to result from a skewed propagation of roughness within the multilayer. A modified film growth model is developed which describes this, and is also used to calculate the nonspecular scattering. The results of the model are in excellent agreement with the measurements. The scattering asymmetry can be used to determine the average deposition angle during the film growth. [S0163-1829(99)05120-6].