Stress relaxation in thin aluminium films

Abstract

Abstract The stress relaxation phenomenon in thin aluminium films deposited onto silicon strips was studied by the cantilever beam technique using X-ray diffraction. At low temperatures the stress decreases linearly as a function of temperature at a rate of −2.17 × 107 dyn cm−2 K−1, in good agreement with the elasticity theory. At high temperatures stress relaxation was observed on heating when the aluminium films could not sustain the compressive thermal stresses created by the difference in thermal expansion between the silicon substrate and the film. Stress relaxation was also found on cooling, for tensile thermal stresses. The activation energy for the compressive stress relaxation was estimated to be 0.43 eV and for the tensile stress relaxation 0.23 eV.