AVS 46th International Symposium
    Thin Films Division Friday Sessions
       Session TF-FrM

Paper TF-FrM5
Stress Evolution during Growth of Epitaxial and Polycrystalline Metal Multilayers

Friday, October 29, 1999, 9:40 am, Room 615

Session: In-situ Characterization and Material Process Imaging
Presenter: V. Ramaswamy, Stanford University
Authors: V. Ramaswamy, Stanford University
W.D. Nix, Stanford University
B.M. Clemens, Stanford University
Correspondent: Click to Email
A complete understanding of the relationship between film stress and microstructure at the various stages of growth and an ability to measure film stress in-situ during growth, provide an opportunity to study film microstructural evolution. In this study, stress evolution during growth of epitaxial and polycrystalline, (111)-oriented Pd/Pt and Pd/Ag multilayers is monitored by in-situ substrate curvature measurement. The initial stress behavior of Pd grown on Ag and Pt is similar in epitaxial and polycrystalline films, with Pd exhibiting a sharp tensile change when grown on Ag and a smaller compressive change followed by a tensile change when grown on Pt. This initial behavior is ascribed to the effects of coherency and surface energy differences between film and underlayer. However, with increasing Pd thickness, remarkable differences are observed in the stress behavior in the epitaxial and polycrystalline samples. In polycrystalline Pd/Pt and Pd/Ag, the tensile stress relaxes with increasing Pd thickness and eventually turns compressive at about 30 Å whereas in the epitaxial samples, the stress in Pd remains tensile even at large thicknesses. The stress behavior of Ag and Pt in Pd/Ag and Pd/Pt multilayers are similar in the epitaxial and polycrystalline cases, with Ag on Pd relaxing completely after the growth of the first monolayer and the development of compressive stress in Pt grown on Pd. The effects of the structural differences between epitaxial and polycrystalline films on the stress behavior are discussed in terms of strengthening mechanisms and susceptibility to the effects of atomic peening.