On the mechanical properties of uhv-deposited Cr films and their dependence on substrate temperature, oxygen pressure and substrate material

Abstract

The internal stress of chromium films was measured in situ by a cantilever beam technique under uhv conditions. At room temperature only tensile stresses are built up in chromium films with increasing thickness. In terms of an earlier published stress model for the origin of the film stress this stress curve is characteristic for materials with high melting point i.e. low mobility and columnar grain growth. At higher substrate temperatures the chromium mobility increases and the resulting stress curves (tensile as well as compressive stresses) indicate an increasingly pronounced island growth mode. Furthermore it is demonstrated that reducing the high chromium mobility at 300°C substrate temperature by increasing oxygen uptake during the metal evaporation results in the changes in the stress curves expected from the stress model. Also the influence of the chemical properties of different substrate materials on the internal stress of chromium films is discussed.