The determination of three-dimensional stress tensors on multilayer thin films

The three-dimensional residual stress condition of copper sputtered on Kapton films was studied by two nondestructive x-ray diffraction techniques. Four samples were evaluated—one control sample, and three heat-treated samples. Because of concerns about steep stress gradients normal to the specimen surface, an experimental technique described by Dölle⁽¹⁾ was used to obtain the residual strain tensors in the near surface region. The resulting stress tensors were compared to data obtained through a modification of the technique described by Dölle, referred to as the differential method.⁽²⁾