Internal interfaces and intrinsic stress in thin amorphous Cu-Ti and Co-Tb films

A combined investigation of intrinsic stress formation by irt situ substrate curvature measurements and of surface morphology evolution by scanning tunneling microscopy during the growth of amorphous Cu-Ti and Co-Tb films is reported. Intrinsic tensile stress and surface morphology are clearly correlated: all films that show intrinsic tensile stress formation in the late growth stages exhibit a cluster-like surface morphology and vice versa. Both the magnitude of the intrinsic tensile stress and the cluster size at the surface depend systematically on the reduced substrate temperature during film preparation, This dependence fits Hoffman's model for tensile stress formation in thin films. Thus, the observed surface clusters are probably the top domes of growth columns, and the atomic mismatch at the column boundaries gives rise to tensile stress formation. (C) 1998 American Institute of Physics.