COMPARATIVE-STUDY OF THE INTERFACE ROUGHNESS OF AG AU AND CU/AU MULTILAYERS WITH SCANNING-TUNNELING-MICROSCOPY AND X-RAY-DIFFRACTION/

The interface roughness is a very important parameter determining the performances of multilayered structures. Ag/Au and Cu/Au textured mult ilayers have been produced by thermal evaporation in an ultrahigh vacu um chamber. After deposition of the Au, Ag, or Cu layer, the surface r oughness at different sampling lengths was probed in situ by scanning tunneling microscopy. After completion of the multilayers, the samples were taken from the ultrahigh vacuum chamber and measured in an x-ray -diffraction unit. Low-angle as well as high-angle specular x-ray-diff raction curves were analyzed using a refinement program which takes in to account layer thickness fluctuations, interface roughness, and crys talline disorder. The average interface roughness, obtained from fitti ng the x-ray-diffraction profiles, is then compared to the roughness o f the film growth front, which was probed with the scanning tunneling microscope. The roughness obtained from the x-ray-diffraction profiles corresponds to a lateral sampling scale which is in good agreement wi th the average grain size within the layers, indicating that x rays sc atter coherently over a volume which is relatively small. Our work als o shows the complementarity of the scanning tunneling microscopy and x -ray-diffraction technique to probe interface roughness of multilayers . (C) 1996 American Vacuum Society.