In-situ Stress Measurements During Cobalt Electrodeposition on (111)-Textured Au
Gery R. Stafford, Matthew R. Fayette, Ugo Bertocci
Cantilever curvature was used to examine stress generation during the electrodeposition of Co from 0.1 M NaClO4 + 0.001 M Co(ClO4)2 (pH = 4.8) in films measuring less than 100 nm in thickness. The stress-thickness product showed a -0.2 N/m compression in the first monolayer followed by increasing tensile stress as the film thickened. The initial compressive stress is most likely due to surface and interface stresses that dominate at submonolayer coverage. Steady state tensile stress, ranging from 0 to 885 MPa, developed in continuous Co films and showed a strong dependence on electrode potential, consistent with stress generating models that appear in the literature. XRD analysis indicates that the Co is face-centered cubic and maintains the (111) texture of the Au substrate, suggesting epitaxial but not pseudomorphic growth on the Au.