High-resolution x-ray diffraction measurements of residual stresses in polycrystalline thin films deposited on single crystalline substrates

A nondestructive method for stress determination in polycrystalline/amorphous thin films deposited on the nearly perfect crystals was developed. High-resolution x-ray diffraction rocking curves are taken from the substrate using a monochromatized and quasiparallel incident x-ray beam. Changes in the rocking curve shape, caused by stress-induced bending of the substrate, are compared with the newly derived analytical expression of the diffraction spectrum, and as a result the radius of curvature and hence the biaxial stress is obtained. For the (004) Si reflection and the Cu K-alpha 1 radiation the radii of curvature within the interval, 3 m < R < 500 m, can be resolved. The method was successfully applied to measure stresses in heat-treated Ni90Ti10 alloy films deposited on a Si (001) substrate. The stress behavior (as a function of the annealing temperature) was found to reflect the sequence of the formation of silicides and enabled the evaluation of their thermal expansion coefficients. (C) 1996 American Institute of Physics.