Nonspecular x-ray reflectivity study of roughness scaling in Si/Mo multilayers

The interfacial roughness and lateral correlation length of a series of Si/Mo multilayers with bilayer period 69 Angstrom and number of bilayers ranging from 5 to 40 have been characterized by diffuse x-ray scattering. Superlattice peaks are preserved in offset radial scans indicating a high degree of conformality in the roughness. The lateral correlation length xi increases with total film thickness h as xi similar toh(0.55); however, the magnitude of the roughness is approximately 2 A for all film thicknesses, in disagreement with scaling laws for self-affine growing surfaces. This observation suggests that interfaces retard the evolution of high-frequency roughness while replicating longer wavelength roughness from one layer to the next (C) 2001 American Institute of Physics.