Thermomechanical behavior of continuous and patterned Al thin films

In this paper, we study the influence of the line width on the mechanical behavior of narrow unpassivated lines of pure Al and Al with 0.5 wt.-% Cu. The stress/temperature behavior during thermal cycling is investigated using x-ray diffractometry. Our results suggest that it is possible to distinguish between two temperature regimes in which different deformation mechanisms take place. At low temperatures, the narrowest lines sustain larger stresses than the continuous films, whereas at high temperatures the opposite behavior was found. Further, iso-thermal stress relaxation measurements on pure Al lines after various heat treatments were performed. These results indicate the existence of a threshold stress below which no deformation of the lines occurs.