1 - Erich Schmid Institute

C.3 Discussion and Concluding Remarks
from the deflection versus film thickness-curve as depicted in Fig.C.6 for three examples.
The characteristic of such a curve allows the estimation of the stress profile because the
actual deflection correlates directly with the stresses in the sublayer removed. After having
removed the thin film in a section, the deflection has a predictable value which comes
solely from the curved indicator, because the substrate is stress free and straight. Since
this deflection is equal for all sections, it gives further information about the accuracy
of the experiment. The sign of the stress in the thin film removed can be estimated
simply from the change of the deflection at the interface (tf = 0µm). A drop indicates
tensile stresses, whereas an increase of the deflection leads to the conclusion that the
stress removed was compressive.
Figure C.6: Examples of measured deflections versus film thickness. The drops of the measured deflections
after having removed the thin film and the diffusion barrier (db) completely in
sections A2 and A3 indicate tensile film stresses. In section A9, the film was subjected to
compressive stresses which leads to an increase of the deflection.
In summary, the presented 3D-ILR method is a powerful tool to determine two- and
three-dimensional stress profiles in surface near layers. The direct approach and the
simple calculation procedure make it a good choice for the evaluation of such stress
distributions with a depth resolution on a nanoscale and a lateral resolution on a micron
scale.
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