Evolution of anisotropic microstructure and residual stress in sputtered Cr films

Abstract

A series of Cr films with varying thicknesses have been prepared using a multiple moving substrate deposition geometry. These films have been investigated with several experimental techniques, including synchrotron x-ray scattering, pole figures, electron microscope, and double crystal diffraction topography. It was found that the in-plane stresses are highly anisotropic in these Cr films. The anisotropic stresses, characterized by two principal stresses in two characteristic directions defined by the deposition geometry, are quantified based on a methodology given in the Appendix. The plan view transmission electron microscopy observations reveal that the Cr films develop well-organized microstructures. The grains, which are elongated along the radial direction, are crystallographically aligned as well. The development of crystallographic texture in the Cr films, further revealed by pole figures and azimuthal (ϕ) x-ray scans, depends on both the deposition geometry and the film thickness. The preferential orientation of film growth is [110] for thinner films (<1.6 μm), and then becomes [111] for thicker films. Correspondingly, the in-plane texture varies in a conformal manner. In the former case, [100] and [110] directions of grains preferentially align along the radial direction and the direction of platen rotation, respectively. In the latter case, the preferential orientation of grains in the radial direction becomes [112], while that in the direction of rotation remains to be [110]. The occurrence of the anisotropic stresses and their dependence on film thickness is related to the evolution of the anisotropic structure and in-plane texture. The correlation is discussed in terms of the modulus effect associated with in-plane texture, the stress relief at intercolumnar voids, and the texture transition. © 2002 American Institute of Physics.