Effect of thin-film stress on the formation of Cr texture and on the coercivity of CoCrX/Cr magnetic thin film

Abstract

The effect of thin-film stress on the formation of Cr texture and on the coercivity of CoCrX(X = Pt, Ta)/Cr magnetic thin films was investigated. The stress was controlled by varying the applied bias and deposition temperature during the film formation. The coercivity of CoCrX/Cr magnetic, thin films was dependent on the grain size of the Cr underlayer and increased with the grain size for a grain size smaller than about 20 nm. This was closely related to the change of Cr texture from the (110) to the (200) orientations. The (200) Cr texture is preponderant over the (110) Cr texture in a deposition condition in which the adatoms are highly energetic and mobile. The (200) texture of Cr thin films tended to suddenly appears at average film stresses smaller than a critical stress. This sudden change of Cr texture is, however, not directly determined by this change of average film. stress. The stress that is critical is, instead, the surface stress. It attains a sufficiently large compressive stress at this critical film stress to energetically favor the (200) over the (110) Cr orientation. The coherency between the film and substrate is not a necessary condition for the formation of the (200) Cr texture. The only requirement is to achieve a dynamic surface structure containing a high density of compressive ledge. This can be achieved not only by controlling the energy of adatoms but also by controlling the average film stress. (C) 2003 American Vacuum Society.