AVS 45th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA3
Characterization of Stress-Morphology Relationships in Sculptured Thin Films (STFs)

Monday, November 2, 1998, 2:40 pm, Room 310

Session: Mechanical Properties of Thin Films
Presenter: R.A. Knepper, Pennsylvania State University
Authors: R.A. Knepper, Pennsylvania State University
D.E. Fahnline, Pennsylvania State University
R. Messier, Pennsylvania State University
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Sculptured Thin Films (STFs) are a recent development in thin film technology wherein a substrate is rotated while a columnar thin film is deposited at varying oblique angles and orientations. The resulting microstructure can thus be engineered into a number of shapes, including non-normal matchsticks, zigzags, coils, and periodically bent nematics (S- and C-shapes). STFs are highly porous and can have properties that differ greatly from both the bulk material and isotropic films of the same material. However, the nature of the relationships between STF morphology and intrinsic deposition stress is not yet understood. In this work, a set of matchstick-shaped STFs has been prepared with varying vapor incidence angles, ranging from 15° 75° from the substrate surface. The deposition results in curvature changes along the two directions of the substrate surface that have been measured by a laser scanning method. These measurements are then used to calculate the biaxial stresses in the films. The measured stresses decrease with decreasing morphology angle, with an abrupt change at a vapor incidence of 45°, and are anisotropic with respect to direction. The stresses measured ranged from 60 MPa to 0.4 MPa. The implications of these results to the general sets of STFs will be discussed. The findings of this research may be used to evaluate future models of the origins of stress in STFs, as well as to control substrate curvature and avoid delaminations.